TI	Electrophysiological evaluation of eyes of insulin dependent diabetic patients without  retinopathy
AU	AbdelMegeed MAS 
IN	Ophthalmology Department, Alexandria University, Alexandria, Egypt. 
AD	368 ElHoreya Street, Moustafa Kamel, Alexandria, Egypt.
EM	Mashrafs@cns-egypt.com
AB 	Purpose: To evaluate different electrophysiological changes in eyes of insulin dependent diabetic patients without retinopathy. Methods: The study was conducted on 74 eyes of 37 patients with insulin dependent diabetes mellitus (IDDM) without diabetic retinopathy. Fifty (50) eyes of 25 normal controls were also examined. All subjects were in the age group 7-29 years. All eyes had best corrected visual acuity of 6/6 , a refractive error < 2.0 D sphere or cylinder, clear media and normal anterior and posterior segments examination with no evidence of diabetic retinopathy. The fasting blood glucose level, and HbA1c in IDDM patients were determined. Electrophysiological examination included: Full field  flash electroretinography (ERG) using a standard protocol, electrooculography (EOG) testing with determination of Light peak/Dark trough (Lp/Dt) ratio and pattern electroretinography (PERG) and pattern visual evoked potential (VEP) examination using a black and white checkerboard pattern with 60o check size reversing at 1.9 Hz. Results:  P100 of the VEP showed significant delay in eyes of IDDM patients even in those with IDDM < 5 years (105.21 ± 3.12 msec) when compared to controls (101.85 ± 3.64 msec). There was a significant correlation between P100 implicit time and duration of IDDM. The oscillatory potential amplitudes were significantly reduced in eyes of IDDM patients (266.62 ± 59.61µV) when compared to eyes of the control group (288.45 ± 33.15 µV) especially with duration of IDDM ≥ 10 years. PERG amplitudes were significantly reduced in those with IDDM ≥ 10 years while Lp/Dt of the EOG was reduced in those with IDDM ≥ 15 years (2.04 ± 0.71) when compared to controls (2.49 ± 0.29). Conclusions: Eyes of IDDM patients show significant electrophysiological functional changes even before the appearance of any retinopathy

TI	Pattern electroretinography and visual evoked potential in glaucoma
AU	AbdelMegeed MAS 
IN	Ophthalmology Department, Alexandria University, Alexandria, Egypt. 
AD	368 ElHoreya Street, Moustafa Kamel, Alexandria, Egypt.
EM	Mashrafs@cns-egypt.com 
AB 	Purpose: to evaluate the pattern electroretinography (PERG) and pattern visual evoked potential (VEP) changes in glaucoma and ocular hypertension, and to identify the most reliable and sensitive stimulus spatial and temporal characteristics for testing. Methods: The study was conducted on 30 eyes with primary open angle glaucoma, 20 eyes with ocular hypertension and 20 normal control eyes. All subjects were in the age group 40 – 70 years with no history of other significant ocular or systemic diseases. All eyes had best corrected visual acuity ≥ 6/9, a  refractive  error < 1.0 D sphere or cylinder and clear media.  The cases were subjected to ophthalmological examination and automated perimetry. PERG and VEP were determined using a reversing black and white checkerboard pattern. Three check sizes (15¢, 60¢ and 240¢) and three temporal frequencies (1.9 Hz, 7.5 Hz and 15 Hz) were used. The amplitudes and implicit times were determined at each check size and repetition rate. Results: Eyes with glaucoma showed significant reduction of amplitudes and delay in implicit time at all spatial and temporal frequencies. Eyes with ocular hypertension showed significant changes only with low spatial frequency (240¢ check size) reversing at high temporal frequency stimulation (7.5 Hz and 15 Hz). In eyes with glaucoma, the PERG and VEP amplitudes showed a significant correlation with the mean deviation of automated perimetry. At 100% specificity, PERG and VEP had a sensitivity of 100% in identifying eyes with glaucoma and 45% in identifying eyes with ocular hypertension. Conclusions: PERG and VEP are simple, rapid and objective tests that can reveal abnormalities in eyes with glaucoma and OHT, even in the absence of cupping or visual field defects. The use of low spatial frequency checkerboard patterns reversing at high temporal frequency increases the sensitivity of these tests in identifying eyes with glaucoma and ocular hypertension..

TI	Prognostic value of electroretinography in central retinal  vein occlusion
AU	AbdelMegeed MAS 
IN	Ophthalmology Department, Alexandria University, Alexandria, Egypt. 
AD	368 ElHoreya Street, Moustafa Kamel, Alexandria, Egypt.
EM	Mashrafs@cns-egypt.com
AB 	Purpose: to evaluate the prognostic value of electroretinography (ERG) in predicting the development of neovascularization (NV) in eyes with central retinal vein occlusion (CRVO). Methods: An ERG protocol was used at patient presentation for 23 eyes with unilateral CRVO and their fellow eyes to define an intensity-response  (I-R) function, scotopic a and b waves implicit times, b/a amplitude ratio, oscillatory potential amplitudes, photopic b wave and 30 Hz flicker implicit times and amplitudes. A Naka-Rushton function was fitted to the I-R data to obtain values for Rmax and logK. Fluorescein angiography was performed within 2 months of presentation. Results: On the basis of fluorescein angiography, 9 eyes (39.1%) were classified into ischemic and 14 eyes (60.9 %) into non-ischemic types. During 9 months follow up, 11 eyes (47.8%) developed NV; 6 (66.7%) in ischemic type and 5 in non-ischemic type (35.7%). Compared to eyes with no-NV, eyes with NV had significantly reduced amplitudes, sensitivity, b/a ratio and significant delays in a wave, b wave and 30 Hz flicker implicit times even in eyes of non-ischemic CRVO that developed NV. Fellow eyes of NV group showed some significant differences from fellow eyes of no-NV group.  Conclusions:  Different ERG parameters obtained early in the course of CRVO can identify eyes at risk of developing neovascularization.

TI	Sensitivity of VEPs versus ERGs in diagnosis of macular disorders
AU	Al-Nahrawy OMM
IN	Ophthalmology Dept, Faculty of Medicine, 
AD	Suez Canal University, Egypt
EM	onahrawy@yahoo.com
AB	Objectives: To study how and when the VEPs and the ERG responses become abnormal in a group of macular disorders. Their sensitivity to macular changes and knowledge of these changes could be used in diagnosis of macular diseases if present behind corneal opacity, cataract or vitreous hemorrhage. Methods: Flash and pattern reversal VEPs and ERGs were tested according to ISCEV standard protocol in 15 eyes with macular disorders. These eyes were as follows: 6 eyes with age related macular degeneration, 2 eyes with cone –rod dystrophy, 2 eyes with acute posterior placoid multifocal pigment epitheliopathy (APPMPPE), and 5 eyes with solar foveal burns. Fundus photography and Fluoroscein angiography documented these lesions. Results:  Macular diseases produced disturbances of the waveforms of both flash and pattern VEP responses. Also there were some small amount of latency delay and reduction of amplitudes of responses. This was proportionate with the area and depth of maculopathy. Photopic ERG responses were less sensitive to macular pathology than VEP responses. Reduction of amplitudes of a and b-waves and some waveform distortion are the main findings. Conclusion: If the fundus oculi is not visible, as in cases of dense cataract, VEPs are a more sensitive tool than whole field ERG in diagnosis of  macular disorders. This is useful in predicting the post-operative visual outcome.

TI	Preoperative Electroretinography for predicting the Visual Outcome  of Vitrectomy in Proliferative Diabetic Retinopathy and  Proliferative Vitreoretinopathy
AU	Badie, O
AU	Shoeir, A
IN	Research Institute of Ophthalmology, Giza, Egypt
AB	Aim: We aimed to evaluate the prognostic value of electroretinography (ERG) in predicting the visual outcome of vitrectomy in proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR) cases. Methods:Vitrectomy was performed on 30 eyes (of 28 patients), 16 with PVR and 14 with PDR. Only patients without surgical or postoperative complications were included. Preoperative ERG was performed for all patients 24 hours prior to surgery. The correlation of the ERG findings to the postoperative visual acuities were analysed. Results: A positive predictive value was found between the preoperative ERG findings and the postoperative visual outcome in vitrectomy cases, the better the preoperative ERG b wave, the better the postoperative visual acuity was improved in the PDR cases. On the other hand, PVR cases did not strictly obey this finding in all the cases. Conclusion: Preoperative ERG can predict the visual outcome of vitrectomy in PDR and PVR cases. Recordability of the b-wave especially, gave the best prediction for viability of the retina. Also a non-recordable ERG response in PVR has a better prognosis than that for PDR.

TI	Results of medical treatment of dysthyroid optic neuropathy in clinical examinations and electrophysiological investigations.
AU	Bernardczyk-Meller, J
AU	Karolczak-Kulesza, M
AU	Meller, M
AU	Pecold K
IN	Department of Ophthalmology, Karol Marcinkowski University of Medical Science, Poznan, Poland
AB	Objectives: The aim of the study was to estimate the effectiveness of medical treatment in patients with dysthyroid ophthalmology, particularly with optic neuropathy, after various therapies, both in clinical examinations and electrophysiological and ultrasound investigations. Methods: The full ophthalmological examinations and electrophysiological and ultrasound investigations were performed in all 50 patients (39 females and 11 males, aged from 36 to 77 years, average age 49 years). Patients with significant exophthalmus, reduced visual acuity, malfunction of eye movement due to pathological changes in the orbit were qualified for the research. Patients with very serious optic neuropathy were treated by intravenous steroids, the others by orbital radiotherapy and oral steroids. The electrophysiological investigations were performed before, during and after treatment. They were repeated every week at the beginning of treatment, and every 2-4 weeks therafter in most patients, during 3-12 months of followup. The electrophysiological investigations – visual evoked potentials – VEPs were performed with Toennies Multiliner Vision equipment with black-white checkboard (30’ and 60’) used as the stimulus. The VEPs analyses were based on three parameters: shape, latency and amplitude of components and all were compared to the results of a control group. Results: In all patients with significant exophthalmus and optic neuropathy we found pathological changes in VEPs  parameters-prolongation of latencies (more than 120 msec) and reduction of amplitudes (less than 6uV). During extra medical treatment we observed improvement of ultrasound results after 7 days and the improvement of electrophysiological results and clinical examinations after 14 days. In VEP results, the amplitudes normalized earlier than latencies. No improvement was observed in patients with more than 6 months history of dysthyroid optic neuropathy. Conclusions: VEPs are objective non-invasive and sensitive tools in the monitoring the influence of systemic steroids and/or radiotherapy on the regression of pathological changes in patients with dysthyroid optic neuropathy. The improvement of electrophysiological parameters is valuable evidence of the effectiveness of treatment.

TI	Checkup of amplitudes and timing of responses recorded with a multifocal system
AU	Bock M
AU	Gerth C 
AU	Lorenz B
IN	Department of Pediatric Ophthalmology, Strabismology and Ophthalmogenetics,
University of Regensburg, Germany
AD	Franz-Josef-Strauß-Allee 11, 93042 Regensburg, Germany 
EM	markus.bock@klinik.uni-regensburg.de
AB	Purpose: To verify both amplitudes and timing of multifocal responses recorded with a VERIS III system. Methods: To be able to record multifocal responses of high reproducibility an electronic circuit was implemented which generates defined electrical pulses after each active m-frame displayed on the VERIS stimulus monitor. Artificial responses were recorded for different recording setups and detector locations on the screen of the stimulus monitor. The results were compared to get more detailed information about amplitudes and timings recorded with multifocal systems. Results: Because of a software problem in the VERIS software versions 3.01 and 3.11 there is an asymmetry between the amplitudes recorded from hexagons on the left and on the right side of the stimulator screen which leads to amplitude changes of the calculated response density values. The biggest difference is found in the most peripheral regions (21% difference if hexagon 27 is related to hexagon 35 and the result of software 3.1 is compared to software  3.3; parameters: 61 stretched hexagon pattern, distance to screen parameter = 30 cm). For standard setups (e.g. 61 hexagons, sample rate 16/frame) the timing of the recorded responses shows minor deviations of a single sample point (0.8ms) at maximum. If combinations of high sampling rates and stimulus patterns with small numbers of hexagons are used (e.g. 32 samples/frame with 7 hexagons), the timing of recordings from different locations of the same  hexagon varies up to 3.8 ms. Conclusions: The reason for the asymmetry of the response density values is a pure solid angle calculation problem of earlier software versions. The recorded data is not affected and the error can be corrected by the use of the evaluation routines of VERIS software 3.3. The correction of the timing differences is handled with the internal “scan delay” parameter. For standard recording protocols, there are 16 samples per frame at least. The more hexagons are displayed on the screen, the more effective the scan delay option gets as the area of single hexagons is reduced and the number of different correction locations rises.

TI	Calibration of Flicker Intensity
AU	Brown MC
AU	Dean G
AU	Wareing PA
IN	Royal Liverpool University Hospital
AD	Clinical Engineering Department, Royal Liverpool University Hospital, Liverpool, L7 8XP, UK
EM	MalcolmBrown@btinternet.com
AB	Purpose To improve the method of calibration of 30Hz flicker intensity.  Methods The suggested method of measuring flicker intensity in the ISCEV guidance notes for stimulator calibration is using an integrating photometer over a fixed number of flashes.  It is acknowledged that rapid flashes at 30Hz may produce lower output than for individual flashes because of the recharge/recovery time of the stimulus device.  Also the method proposed is not applicable to all electrodiagnostic systems because the number of flashes cannot be set.  A more simple method is proposed and examined which requires only a simpler calibration device showing only continuous output.   In this method the stimulator is set for a particular rate (e.g. 30Hz) and is run for a few seconds and the recording device is a photometer set in its continuous monitoring mode but with time constant long enough to average the light intensity. Results We demonstrate the results of this method applied to two very commonly used Ganzfeld stimulators to show how the flicker intensity differs from the individual flash intensity at the same settings.  We also demonstrate how this compares with the integrating method as set out in the ISCEV calibration guidance notes. Conclusion The method proposed appears to be a reliable and simpler method of determining flicker intensity than those currently proposed.  The ratio between flicker and individual flash intensities deviate in some proportion to the nominal individual flash intensities.

TI	Congenital absence of the chiasm.  Demonstration of an uncrossed visual pathway using monocular flash visual evoked potential 
AU	Brown MC
AU	Hallet C
AU	Anbarusu A
AU	Kaye SB
IN	Royal Liverpool University Hospital
AD	Clinical Engineering Department, Royal Liverpool University Hospital, Liverpool, L7 8XP, UK.
EM	MalcolmBrown@btinternet.com
AB	Purpose – To demonstrate flash visual evoked potential testing to diagnose absence of the chiasm.  A two year old girl was referred at Alder Hey Children’s Hospital, Liverpool with nystagmus associated with head oscillation and poor visual acuity recorded at 6/19 in each eye.  The patient was referred for possible cone dystrophy.  Methods – Flash VEP was employed with two channel recording between Fz and O1, O2 placed 4 cm each side of Oz.  Results – Responses to flashes with binocular viewing showed symmetrical and normal looking responses over each lobe of the visual cortex.  However when each eye was patched in turn, stimulation of the right eye produced responses similar to the binocular response on the right occipital electrode with a poorly discernable response over the left occipital electrode.  These responses were reversed when the left eye was stimulated.  This is the opposite to the results obtained in preceding patients with similar test conditions with albinism in which the better response was obtained over the contra-lateral hemisphere and an abnormal response from the ipsilateral hemisfield.  We discuss here the  possible explanation that the patient had a reduction in the proportion of fibres decussating at the chiasm compared with the increased decussation in the albino patients. An MRI of our patient subsequently showed the absence of the chiasm. Conclusions The abnormality of the absence of the chiasm was shown first by the VEP findings.  To our knowledge this is one of only a few cases reported with congenital absence of the chiasm detected in this way.

TI	Improving recording quality by using infrared video inside the Ganzfeld Stimulator.
AU	Brown MC.
IN	Royal Liverpool University Hospital
AD	Clinical Engineering Dept., Royal Liverpool University Hospital, Liverpool L7 8XP UK
EM	MalcolmBrown@btinternet.com
AB	Purpose -To investigate the benefits of using infrared video inside the Ganzfeld stimulator for recording ERG, EOG and flash VEP.  Methods  A CCD camera was fitted to a Ganzfeld Stimulator to view the face of the patient through a pinhole.  Infrared LEDs were fitted facing inwards to reflect from the coating of the bowl onto the face of the patient.  The patient’s face was viewed from a TV monitor on the operator’s console and a video recorder and microphone was employed to log the essential events of the session.  Results  A sequence of video examples has been assembled which show the deviations in the behaviour of patients from that desired and I will discuss their effects on the validity of the results. I will also show how the view of the patient enabled these problems to be corrected by directly instructing the patient.  A number of the examples are with children and show that considerable improvement in behavior within the bowl can be obtained if the operator has a good view of the patient’s eyes and the recording electrodes.  Conclusions – Considerable improvement in recording quality, and confidence in the results, can be achieved by the use of direct video viewing of a patient who has the head within the Ganzfeld bowl.  Examples are where the patient looks away from the fixation light, where they close or partially close their eyes in response to the stimulus (particularly flicker), where the electrodes become displaced,  and in the case of the EOG where they do not follow the instructions or deliberately ignore them.

TI	Visual function in intra-uterine growth-restricted guinea-pigs
AU	Bui* BV
AU	Armitage* JA
AU	Caddy# J,
AU	Rehn# AE 
AU	Rees# SM
AU	Vingrys* AJ
IN	Optometry and Vision Science, University of Melbourne, Vic 3010, Australia*
IN	Anatomy and Cell Biology, University of Melbourne, Vic 3010, Australia#
AB	Purpose: To evaluate the retinal function (ERG) of spontaneously and surgically induced intra-uterine growth-restricted mammals. Methods: Three spontaneously growth-restricted and three surgically induced growth-restricted guinea-pigs (English-Shorthair) had their ERGs measured at 8 weeks of post-natal age and were compared to a cohort of seven age-matched siblings. The surgical induction was achieved by ligating the intra-uterine artery at 30 days gestation (term 67 days) thus severely restricting uterine arterial supply as described by Rees et al. (1992). Two responses to white flashes (strobe discharge (Vivitar 285) Ganzfeldt) were collected over 7.5 log units of light attenuation with an inter-stimulus interval of 90 sec after prior overnight dark adaptation and anaesthesia (Xylazine 5mg/kg, Ketamine 35mg/kg). Signals (250msec epochs) were recorded using a custom made Burian-Allen bipolar electrode via a Grass amplifier (P55: x10,000, 3dB down, 0.1-10,000 Hz) and digitised at 2kHz. We present data on a-wave, b-wave (peak-to-peak) and Oscillatory potential (OP) amplitudes and implicit times. OP amplitudes were extracted (55-200 Hz) and modelled using a Gabor function. One normal animal had ERGs recorded after ON-bipolar cell isolation with APB (2mM at the retina). Results:  One surgically induced growth-restricted guinea-pig showed no post-receptoral response with the resultant waveform (P3) resembling that of the APB isolated animal. The rest of the group showed more subtle deficits. On average, their a-wave amplitudes were normal but implicit times were delayed (1.98 msec, p<0.05). The b-wave amplitudes were normal for both cone and rod mediated functions, but the rod implicit time was significantly (3.93 msec, p<0.05) delayed in the presence of a normal cone timing. OPs showed deficits in both amplitude (51%, p<0.01) and timing (2.72 msec, p<0.05). Conclusion:  We believe that our findings can be interpreted as indicating for subtle photoreceptoral damage that produces the aberrant timing and an inner-retinal deficit produces the OP abnormality.
Ress S, Bainbridge A (1992). Int J Dev Neurosci. 10:93-108.

TI	Extraction and modelling of oscillatory potentials in human and animal electroretinogram
AU	Bui BV
AU	Armitage JA
AU	Vingrys AJ
IN	Department of Optometry and Vision Sciences, University of Melbourne
AD	Parkville, Victoria, 3010, Australia
AB	Purpose: To develop a model to describe intensity-response characteristics of the oscillatory potentials (OPs) in human and a common laboratory animals. Methods: OP visualisation is hampered by artefacts produced by the a-wave, which can contain a Fourier spectrum that overlaps the OPs themselves. To minimise this OPs can be extracted using a method suggested by Bui et al. (1998). Such extraction yields waveforms that resonate with Gabor-like characteristics. We fitted these extracted OPs using a Gabor function, which is a convolution of a gaussian envelope with a sine wave carrier. The OP extraction and modelling was performed on electroretinographic responses achieved with a Ganzfeld stimulus (discharge source Vivitar 285) on a cohort of 5 humans and 6 guinea-pigs (English-Shorthair) over a range of 6 log units of light (unattenuated 5.5 log cd-s.m-2 in 0.4 log unit steps) with an interstimulus interval of 180 seconds. Human subjects were dark adapted for forty five minutes prior to experimentation and data were acquired at 2kHz using the UTAS-2000 (LKC technologies). A jet electrode was used with an amplification of x1000 and bandpass filtering (0.5-3000Hz). Animals were dark adapted overnight and anaesthetised with a standard mix of Ketamine (5mg/kg) and Xlyazine (35mg/kg).  Signals were collected using a Burian-Allen electrode also acquired at 2kHz, amplified x10000 (Grass P55) and bandpass filtered (0.5-3000Hz). Results: Oscillatory potentials were observed across a stimulus range of 2 log units, and show intensity-response characteristics analogous to other ERG components. The extraction paradigm returned timings and amplitudes that closely resembled the raw OPs for both human and guinea pig waveforms. Further evaluation (Q-statistic) suggests that the Gabor model provides an accurate description of both human and guinea pig OPs. In addition, we show that the model can be applied across a range of intensities. Conclusions: Extraction of the b-wave leading edge and modelling the resultant waveform using a Gabor function provided accurate descriptions of OPs. The modelling gave good fits in terms of the Q-statistic. In addition, we show that such a model provides a reliable description of OPs present in both human and animal waveforms across a range of intensities.
Bui BV, Weisinger HS, Sinclair AJ, Vingrys AJ. (1998) Doc Ophthalmol. 95:15-34.

TI	A comparative study of services, techniques, referral patterns and equipment in a representative sample of visual electrophysiology centres in Australasia. 
AU	Chelva E
AU	Atkinson JM
AU	De Roach JN
AU	Kay SMS
AU	McLaren TL
AU	Price RI
IN	Department of Medical Technology and Physics, Sir Charles Gairdner Hospital
AD	Sir Charles Gairdner Hospital, Perth, Western Australia
EM	Johnd@mtp.pd.uwa.edu.au
AB	Purpose: To compare tests performed, techniques applied, referral patterns, and types of equipment used, in visual electrophysiology centres throughout Australasia. Methods:. A questionnaire was sent to 24 centres known to us that carried out visual electrophysiology and results from each section of the questionnaire were then tabulated. Results: Fourteen questionnaires were returned completed. Also, 3 centres indicated that they no longer carried out electrophysiology. Of the 14 responses, 2 centres carried out VERs only, 2 had access to multi-focal techniques only, and the remaining 10 provided a broad range of visual electrophysiological services. These 10 centres typically performed standard ERGs (including flicker ERGs), VEPs and EOGs. Oscillatory potential ERGs were routinely carried out in 7 centres, and transient PERGs in 5 centres. Other tests that were available but rarely requested included focal ERG, steady state PERG, and sweep VEP. Four centres had multi-focal techniques available, but only one used this technique routinely. Approximately two-thirds of responses indicated that retinal dystrophies and unexplained visual loss were the main referral diagnoses. Two outliers were one laboratory with 40% glaucoma patients, and another with 50% drug toxicity assessments. Most centres used gold foil, DTL fibre or skin electrodes for ERG. Four centres used contact lens electrodes, but 2 of these centres performed ERGs predominantly under sedation. HK loop, DTL fibre or gold foil electrodes were all in use for PERG. A total of 13 data collection systems were in operation at the 10 general sites, 8 of which were assigned a level of satisfaction (out of 10) of 7 or better. Two centres rated their equipment as less than 5. Research interests varied greatly, and there was no collaboration noted between any of the respondents. Conclusions: General visual electrophysiology centres around Australasia tend to provide ERGs, flicker ERGs, VEPs and EOGs as standard tests, while approximately half also routinely perform transient PERGs and oscillatory potential ERGs. Tests that are available but seldom requested include sweep VEPs, focal ERGs, steady state PERGs and multi-focal VEPs or ERGs. This study highlights the desirability for the establishment of a special interest group, for the sharing of research interests, equipment experiences, possible new service opportunities (such as retinal toxicity and glaucoma studies), with a view to further improving and strengthening the contribution of diagnosis of eye disease through visual electrophysiology.

TI	Serial visual electrophysiological correlates in  birdshot retinochoroidopathy
AU	Coupland SG
AU	Hodge W
AU	Kertes P
AU	Bawazeer A
IN	University of Ottawa Eye Institute, Ottawa, ON, Canada.
AD	Ottawa Hospital-General Campus, 501 Smyth Road, Ottawa, ON, Canada  K1H 8L6
EM	scoupland@ogh.on.ca
AB	Purpose Birdshot retinochoroidopathy is a rare, chronic posterior uveitis with a distinctive clinical presentation. Visual electrophysiology findings indicate varying degrees of middle, retina, photoreceptor and possible RPE involvement. The ERG may be supernormal in the early stages; however, with disease progression the ERG b-wave diminishes followed by the a-wave until the ERG is completely extinguished. The EOG Arden ratios have also been reported as subnormal in 50 to 75% of patients with Birdshot retinochoroidopathy. Herein we report the serial ERG and EOG findings in two treated patients.  Methods Two patients (Cases 1 and 2) presented with Birdshot retinochoroidopathy.  The diagnosis of Birdshot retinochoroidopathy was based upon fundoscopic, clinical examination findings along with positive HLA A29 typing.  Both cases were treated with corticosteroids. ERGs were recorded through dilated pupils with DTL fiber electrodes under scotopic (blue) flash, photopic 30 Hz. flicker and white flash conditions, using the Pathfinder II (Nicolet Instruments) visual electrodiagnostic system. EOGs were recorded during 12 minutes of dark and light adaptation according to the ISCEV standard. Results In Case 1, in both eyes, initially the scotopic ERG b-waves were reduced in amplitude and had delayed implicit time. The photopic flash ERG b-wave was normal in amplitude but delayed in implicit time.  The a-waves were normal with regards to amplitude and implicit timing for both scotopic and photopic flash conditions.  30 Hz flicker trough-to-peak amplitude was reduced.  Follow-up ERG after 5 months steroid therapy were essentially unchanged.  By 10 months, scotopic ERG b-wave amplitudes were borderline normal in amplitude and had normal implicit timing. The photopic flash and 30 Hz flicker had normalized.  There was concomitant improvement in the patient’s color vision and symptoms.  In Case 2, initially the ERG was normal but EOG showed reduced Arden ratio in both eyes. Four repeat visual electrodiagnostic studies were performed over the 10 months of steroid therapy.  ERGs remained normal during that time and EOG Arden ratio improved.  There was also concomitant improvement in the patient’s color vision and symptoms. Conclusions Serial ERG and EOG recordings can be valuable in recording the progressive course of this disease as well as in documenting response to drug therapy.

TI	Proposal for an international normative ERG database using the ISCEV standard for clinical electroretinography
AU	Coupland SG
IN	University of Ottawa Eye Institute, Ottawa, ON, Canada.
AD	University of Ottawa Eye Institute, Ottawa Hospital-General Campus, 501 Smyth Road, Ottawa, ON, Canada  K1H 8L6
EM	scoupland@ogh.on.ca
AB	Purpose Over a decade has passed since a basic ERG protocol was standardized so that certain responses could be recorded comparably  throughout the world (Marmor et al., 1989).  The ERG standard has since been updated in 1994 and 1999.  Recommendations have been made that commercial recording equipment have the capability to record the standard five ERG responses and numerous commercially available electrodiagnostic systems conform. Unfortunately, there are serious impediments to collecting laboratory normative data.  The practice is both labor intensive, time consuming and expensive. This is especially true when another or different electrodiagnostic system is purchased.   A cooperative multi-center collaboration at normative data collection would have several advantages including reduction in cost, resources and testing time  to the participants.  Recently, a new visual electrodiagnostic system, the Espion (Diagnosys LLC) has become available.  The purpose here  is to propose the establishment of an international normative ERG  database for Espion users conforming to  the ISCEV Standard.   Methods   An ERG protocol conforming to the ISCEV Standard for clinical electroretinography (1999 update) will be distributed to those centres having an Espion system and choosing to participate. The software will allow identification and flagging of “normal” subjects to distinguish them from patients and will also implement web access capability to allow the exporting of normative ERG waveforms from individual users to a central user website.  Patient anonymity will be maintained, but site identification and additional information including subject’s age, gender, race, dilated pupil size and refraction will be included with the ERG waveforms. Once exported to the website the individual waveforms will be visually inspected to maintain quality control. Waveforms will be processed and appropriate summary descriptive statistics for ERG parameters under the standardised ISCEV conditions will be developed.  Results Normative values will be made available to participants through the user website, which can be downloaded to authorised users and incorporated into their operating system software to automatically flag those parameters that exceed normal limits, when testing patients. Conclusions The establishment of a multi-center collaboration at normative data collection in clinical electroretinography using the ISCEV standards would have significant advantages to participants in time saved, resources spent and access to larger sample size.

TI	The role of functional testing in differential diagnosis of congenital achromatopsia
AU	Farkas A.
AU	*Wenzel K.
AU	Vamos R.
AU	Gyory J.
IN	2nd Dept. of Ophthalmology, Semmelweis University of Medicine, Budapest, Hungary (H-1085 Budapest Maria Str.39.)
IN	*Dept. of Precision Mechanics and Optics, Technical University of Budapest, Hungary
EM	farkasag@szem2.sote.hu
AB	Purpose: To characterise different types of congenital achromatopsia through the use of electrophysiological and psychophysical measures. Methods: Clinical, electrophysiological and psychophysical examinations were carried out in three patients with congenital achromatopsia: a 31 year-old male, a 58 year-old female and a 6 year-old boy. The clinical test battery included visual acuity, anterior segment and fundus examination. The electrophysiological test employed was the ERG. The psychophysical tests used were: color vision, dark adaptation, spectral luminosity, visual field and CFF examinations. Results: The clinical examinations demonstrated classical signs of typical congenital achromatopsia, which had been present in all patients since early childhood: poor visual acuity, photoaversion, absent color discrimination, nystagmus and maculopathy. The diagnosis was confirmed by definitely subnormal photopic flash, and extinguished photopic flicker, ERG responses, which indicated severe deterioration in cone function. There was a striking difference between both the dark adaptation curves and spectral luminosity curves of the patients. The male patient (case 1.) had a monophasic dark adaptation curve and maximal spectral luminosity at 507 nm. He can thus be considered a complete achromat. The dark adaptation curve of the female patient (case 2.), however, was biphasic and her spectral luminosity curve had a maximum at 527 nm, a value between that of the rods and the middle wave sensitive (MWS) cones. These data suggest the presence of other functioning photoreceptors, which exhibit cone-like characteristics, in addition to rods. This case represents a variation of incomlete achromatopsia. The boy's (case 3.) dark adaptation curve had a slightly biphasic shape and the peak of his spectral luminosity curve was at 467 nm, which corresponds that of he blue (SWS) cones. This patient appears to be a blue cone monochromat.
Conclusion: Due to its typical symptoms, congenital achromatopsia can be suspected on the basis of clinical examinations, but an ERG is essential to confirm the diagnosis. Complete and incomplete forms can be differentiated by a dark adaptation test. Further differentiation of the incomplete form is possible by spectral luminosity measurements. 
The importance of an early diagnosis will be stressed.     

TI	Complementary value of fullfield and multifocal ERGs recordings
AU	Goub Inna
AU	Grigg JK
AU	Billson FA
IN 	SaveSight Institute, Department of Clinical Ophthalmlogy, University of Sydney.
EM	inna@eye.usyd.ed.au
AB	Purpose: To investigate complementary value of fullfield and multifocal ERGs tests in patients with retinal dysfunction. Methods: Fullfield and multifocal ERGs were recorded simultaniously from 193 patients with retinal diseases. Normal reference values for fullfield and multifocal ERGs were previously established for adults aged between 18 and 50 years old. Fullfield ERGs were performed using Ganzfeld flashes using skin electrodes under both scotopic and photopic conditions; 90° of the retina was stimulated. Multifocal ERGs were recorded using the VERIS-3 system using a gold contact lense electrode under photopic conditions. The central 50° of the retina was stimulated. Results: Four major groups of patients were revealed:
1     The patients with abnormal fullfield ERG and abnormal multifocal ERG
2	The patients with normal fullfield ERG and abnormal multifocal ERG.
3	The patients with flat fullfield ERG and remaining macular responses in multifocal ERGs.
4	The patient with abnormal but still recordable fullfield ERG and flat multifocal ERGs
Conclusions: Fullfield ERGs and multifocal ERGs performed simultaniously in most patients with retinal dysfunctions demonstrate diagnostic importance in clinical practice and allows close monitoring in advance cases of the diseases.

TI	Evidence for EOG abnormalities in patients with pigment dispersion syndrome and pigmentary glaucoma
AU	Greenstein VC 
AU	Seiple W 
AU	Ritch R
IN	New York University School of Medicine, Department of Ophthalmology, 550 First Avenue, New York, NY 10016, USA
EM	vcg1@is3.nyu.edu
AB	Purpose. Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are characterized by disruption of the iris pigment epithelium, deposition of the dispersed pigment granules throughout the anterior segment and an increased incidence of lattice degeneration of the retina. The pigment epithelium of the anterior and posterior segments of the eye have a common embryological origin and it has been suggested that the retinal pigment epithelium (RPE) is also involved in PDS1,2. The purpose of this study was to test the hypothesis that the integrity of the retinal pigment epithelial (RPE)/photoreceptor complex is affected in patients with PDS or PG. Methods. The integrity of the RPE was assessed with electro-oculography. Electro-oculograms (EOGs) were recorded from patients with the following diagnoses: PDS, PG, primary open-angle glaucoma (POAG), and ocular hypertension (OHT). Pupils were dilated and eyes were pre-adapted to room light levels of 60 lux for 20 minutes. EOG values were then recorded during 15 minutes of dark adaptation followed by 15 minutes of light adaptation (2700 cd/m2). For each subject, dark-trough amplitudes, dark-trough latencies, light-peak amplitudes, light-peak latencies and ratios of the light-peak amplitude to dark-trough amplitude (Arden ratios) were calculated. Results. One-way analysis of variance of the Arden ratios indicated significant differences among the groups, p<0.001. A post-hoc Newman-Keuls test revealed that the mean Arden ratios of the PDS group and the PG group were significantly lower than the mean Arden ratios of the control group, the POAG and the OHT group. Conclusion. The decreased ratios suggest that the integrity of the RPE/photoreceptor complex is affected in PDS and PG. 
1. Cardillo, Piccolino, Calabria et al. (1989) Graefe’s Arch. Clin. Exp. Ophthalmol. 2. Scuderi, Ricci, Nucci et al. (1998) Ophthalmic Res. 

TI	Visual evoked potentials in epilepsy patients on Carbamazepine (Finlepsin)
AU	Guekht AB 
AU	Shpak AA
IN	Russian State Medical University
AD 	Prof. A.Guekht  Prospect Mira, 118-A apt.46 Moscow 129164 Russia
EM 	1575.g23@g23.relcom.ru
AB 	Purpose. The goal of this study was to evaluate the role of visual evoked potentials (VEP) in prognosis of Carbamazepine (Finlepsin) efficacy in epilepsy patients. Methods. Transient VEPs were elicited by checkerboard pattern of 30’ checks reversing 1 once per 1 s. Monocular stimulation was performed. The active electrodes were located at Oz, O1 and O2. VEPs were registered in 35 newly diagnosed  patients (age range 25-52 years) with symptomatic localization-related epilepsy and 25 healthy controls. Patients were studied before and 1, 3 and 6 months after the initiation of treatment with Finlepsin. Results. Twenty-five patients were successfully treated with Finlepsin: 18 were without seizures and in 7 patients the frequency of seizures reduced significantly. The other 10 patients had almost no changes in the frequency of seizures on therapeutic doses. Before treatment VEPs had normal latency, and their most characteristic features were increased mean amplitude of P200, and afterdischarge (in 57% of patients). Patients on Finlepsin demonstrated prolonged (by 25-30 ms) latency of main VEP peaks as compared to initial data and controls. At the same time the dynamics of amplitudes of VEP peaks was different in patients with different efficacy of Finlepsin. In successfully treated patients the mean P100 amplitude tended to decrease, with this change occurring in several cases even before the control of seizures was obtained. At the same time, in some drug-resistant patients the amplitude of most peaks, especially that of P100, increased slightly or significantly in spite of treatment. The mechanisms and clinical relevance of VEP peaks amplitude changes in epilepsy patients need further investigation, though  results of this study suggest  the prognostic significance of these changes early in the course of antiepileptic treatment. Conclusions. Increased amplitude of P200 and afterdischarge was found in patients with epilepsy. The latency of principal VEP peaks increased in all epilepsy patients treated with Carbamazepine (Finlepsin). Decrease of P100 amplitude could be an early prognostic sign of the efficacy of the drug. Assessment of pattern-reversal VEP could be useful in the examination of epilepsy patients.

TI	Multifocal cone and rod responses in patients with progressive cone dystrophy. 
AU	Holopigian K
AU	Seiple W
AU	Greenstein VC
AU	Hood DC
AU	Carr RE
IN	New York University School of Medicine, Department of Ophthalmology
AD	550 First Ave., New York, NY 10016.
EM	kh19@is3.nyu.edu
AB	Purpose. The purpose of this study was to examine local cone and rod psychophysical and electrophysiological function in patients with progressive cone dystrophy (CD). Methods. Cone-mediated threshold visual fields, cone multifocal ERGs, rod-mediated threshold visual fields and rod multifocal ERGs were measured in a group of patients with CD. Results. Cone-mediated threshold fields were elevated, with the central retinal areas most affected. The cone multi-focal ERGs were significantly reduced in amplitude and markedly delayed throughout much of the area tested. There were significant correlations between cone amplitude and cone implicit time for the majority of the patients. The correlations between the cone multifocal ERG parameters and visual field loss were not significant. Rod-mediated thresholds were elevated in some areas of the visual field, consistent with the involvement of the rod system in these patients. In addition, rod multifocal ERG responses were reduced in amplitude and delayed at some retinal locations. Rod multi-focal ERG losses were typically greatest at the more peripheral locations. The rod multi-focal ERG results were poor predictors of rod visual field thresholds. Conclusions. Patients with CD have local cone-mediated threshold and multifocal ERG deficits. The electrophysiological abnormalities were more extensive than the threshold abnormalities. The patients with CD also demonstrated local rod threshold and ERG deficits. The rod system losses were less severe and more localized than the cone system losses. There was little correspondence between the topography of the cone and rod system losses in these patients. 

TI	The functional evaluation of retinal vascular occlusion with electroretinogram.
AU	Huang-SZ
AU	Wu-LZ
AU	Luo-TQ
AU	Wu-DZ
IN	Zhongshan Ophthalmic Center
AD	Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Science, 54, Xianlie Road, Guangzhou, 510060, China.
EM	shizhouh@163.net
AB	Purpose To evaluate the functional change of retinal vascular occlusion with electroretinogram, 30 cases (31 eyes) of central retinal vein occlusion (CRVO), 15 cases (15 eyes) of branch retinal vein occlusion (BRVO), 7 cases (7 eyes) of central retinal artery occlusion (CRAO) and 6 cases (6 eyes) of branch retinal artery occlusion (BRAO) were tested with Ganzfeld electroretinogram. Method The scotopic ERG was evaluated with I1 blue light and I16 white light stimulation. The photopic ERG was tested with I16 red light and I8 white light stimulation (ISCEV ERG standard). The amplitudes and latencies of a waves and b waves were measured. Results ERG abnormalities were most obvious in CRVO, followed by CRAO and BRVO. The rate of ERG abnormalities was the lowest in BRAO. The comparison between the affected eyes and the fellow eyes with normal visual acuity showed that statistically significant amplitude differences in SI1B b, SI16W a, SI16W b, PI8W a and PI8W b in CRVO, SI1B b and PI8W b in BRVO and all stimulation conditions except the SI16W a and SI16W b for CRAO and BRAO. The comparison between the affected and normal fellow eyes showed statistically significant difference of latencies in all of the stimulation conditions for CRVO and BRVO, and all of the stimulatioon conditions except the PI16R a, PI16R b and PI8W a for CRAO and BRAO. Conclusion The fact that b waves were more affected suggests that retinal vascular occlusion produces more severe abnormal function in middle retinal layers than in outer retina layers.

TI	S-cone topography in normals and blue-cone monochromats
AU	Jägle H
AU	Albrecht JF
AU	Baseler HA
AU	Seeliger M
AU	Sharpe LT
IN	Dept. of Pathophysiology of Vision & Neuro-Ophthalmology, University Eye Clinic
AD	Schleichstr. 12-16, D-72076 Tübingen, Germany
EM	herbert.jaegle@uni-tuebingen.de
AB	Purpose To develop a standard procedure for measuring short-wavelength sensitive (S-) cone topography in normals and clinical patients. Methods Subjects included four normals, two S-cone monochromats and a rod monochromat. Their multifocal ERGs (mERGS, VERIS) were measured with a DTL fiber electrode, using black/white or colored stimuli generated on CRT monitors and LCD displays.  The stimuli were 61- or 103-element arrays of hexagonal cells, which subtended 58° x 50° of visual angle. The monitors and displays were spectrally and photometrically calibrated. To selectively stimulate S-cones, a silent substitution method was combined with adjustable constant adaptation fields. Selective pigment bleaching techniques designed to reduce the long-wavelength sensitive (L-) and mid-wavelength sensitive (M-)-cone responses as well as the rod responses were also employed. Additionally, an SLO based system (RETIscan driving a HRA Heidelberg SLO) with a blue laser (488nm) was used to record S-cone mERGs. To reduce L- and M-cone and rod contributions to the signal, between each m-sequence, a bright yellow light (572nm; 6100cd/m2) was used to bleach c. 60% of the L- and M-cone and 99% of the rod pigment. Results were analyzed by averaging data in iso-eccentric rings or over the entire array. We also applied a time-varying filter to remove noise from the signals. Results  The topography of S-cone ERG responses could be revealed for the normals and S-cone monochromats using either a combination of cone-substitution and chromatic field adaptation or using the SLO based system combined with a pigment bleaching procedure. The delay of the b-wave peak of the S-cone response was related to the effective cone contrast as well as the adaptation state.  Depending on the contrast and intensity conditions, it was 50-60 ms with the SLO system and 50-80 ms with the CRT or LCD displays. Conclusions For S-cone isolating stimuli presented on standard color monitors, S-cone responses have a very low amplitude.  They only be clearly identified by using additional chromatic adapting fields selected to reduce the L- and M-cone as well as the rod contribution to the signals. The 488 nm laser of the SLO provides a much better signal.  However, because it also stimulates the L- and M-cones, it must be used in conjunction with a pigment bleaching procedure. The SLO system also has the disadvantage of a very slow frame rate. To routinely obtain robust S-cone signals, very bright cone-isolating stimuli combined with an adaptation field are required.

TI	Separation of USH syndrome I and II by ERG implicit time
AU	Jaissle GB.
AU	Seeliger MW.
IN	University Eye Hospital, Dept. II, 
AD	Tuebingen, Germany
EM	see@uni-tuebingen.de
AB	Purpose: To describe ERG implicit time differences between Usher syndrome (USH) patients, and to propose a new clinical test for the electrophysiological separation of USH I and II. Methods: Standard ERG and a 33 Hz photopic microflicker were obtained from each of 15 controls, USH I, USH II, and RP patients. In selected patients, multifocal ERGs (MF-ERGs) were also recorded using the Tuebingen standard conditions. The 33 Hz flicker waveforms consistently showed 3 peaks, whose implicit times were determined separately. For testing, a score S was calculated as the sum of the three peak implicit time values of each subject. The sensitivity, specificity, and receiver operating characteristic (ROC) of the proposed test were calculated. Results: The MF-ERG revealed a lack of im-plicit time delay in USH I patients that is typical for RP. Verification of this finding in standard ERG data was difficult because the signals were often too small. Thus, the 33 Hz microflicker, the response that is pre-served longest, was evaluated. Although the 33 Hz flicker showed some variability in shape, three peaks were more or less clearly discernible in all subjects. Peak implicit times of the USH I patients were similar to normal, whereas the implicit times of the USH II patients were similar to those of the RP group. The overlap between normal/USH I and RP/USH II was minimal, and the respective group differences highly significant. We cal-culated a sum score S for each subject to reduce variability in the determi-nation of peak times. The ROC curve for a test between USH I and II based on the score S yielded a sensitivity and specificity of about 95% with a cutoff of 73 ms. Conclusions: In contrast to RP and USH II, implicit time delay is low or absent in USH syndrome type I despite substantial amplitude reduction. This difference can be used diagnostically to separate USH I and II with a high degree of sensitivity and specificity. One might speculate that USH I progresses so that there are only functional or non-functional cones, but no "suffering" cones to produce the delay.
Supported by the DFG (SFB 430, project C2) and fortuene grant 517

TI	Electrooculography and pattern ERG in the diagnosis of Best's disease
AU	Jarc-Vidmar, M
AU	Popovic, P
AU	Brecelj, J
AU	Hawlina, M
IN	University Eye Clinic and University Institute for Clinical Neurophysiology
Ljubljana, Slovenia
AB	Objectives: It is still an unresolved question whether the primary site of the lesions in patients with Best's disease is at the level of the retinal pigment epithelium or in the neurosensory retina. The aim of the study was to asses the function of inner retinal layers in patients with different stages of Best's disease using pattern ERG, as there is increasing evidence that pattern ERG is abnormal in defined forms of macular degenerations.Methods: ISCEV standard electrooculography, photopic and scotopic ERG, pattern ERG and VEP were recorded in 12 patients (24 eyes) with different stages of Best's disease. Results were compared to visual acuity and visual fields measured with kinetic and static perimetry. Results: In 14 eyes with initial stages of the disease (visual acuity better than 0.6) PERG responses were normal despite clinically evident macular changes, whereas in in eyes with advanced forms of the disease (visual acuity less than 0.6) there were reduced PERG responses in 6 eyes. Full field photopic and scotopic ERGs on the other hand were normal in all the patients. Visual field measured with static perimetry showed small central scotoma and pathologic values of MD and CLV already in patients with good visual acuity and still normal PERG responses. Conclusions: It seems that the primary site of lesion in patients with Best's disease lies at the level of RPE, with the neurosensory retina beeing affected secondarily. Besides electrooculography, static perimetry is a very sensitive indicator of initial stages of Best disease where other electrophysiological tests (PERG and ERG) are still in the normal range.

TI	Acquired non-vascular unilateral inner retinal dysfunction.
AU	Kaushal S
AU	Koh AH
AU	Hogg CR
AU	Holder GE
IN	Moorfields Eye Hospital, City Road, London EC1V 2PD, UK
AD	Moorfields Eye Hospital, City Road, London EC1V 2PD, UK
EM	graham.holder@moorfields.nthames.nhs.uk
AB	Purpose: To describe the clinical features in seven patients with unilateral negative ERG in whom a vascular aetiology has been excluded. Methods: Retrospective review. 128 of 2640 ERGs showed a negative waveform. Seven of these patients had a unilateral negative ERG, with exclusion of a vascular aetiology. Electrophysiological examination incorporated routine ganzfeld ERGs and pattern ERGs supplemented in six patients by examination of ON- and OFF- responses using extended duration stimuli. Some patients also underwent further investigation such as fundus fluorescein angiography or fundus autofluorescence imaging. Results: All seven patients had markedly abnormal cone derived ERGs. In the six cases where ON- and OFF- response examination was performed the OFF- response was relatively or completely spared, suggesting principle involvement of the depolarising bipolar cell pathway. Inflammatory disease was suggested on history and/or examination in five patients. Biochemical and immunological investigation failed to reveal a definite cause in any patient. Conclusions:  Non-vascular unilateral negative ERG is rare. One previous report has described acquired unilateral night blindness with selective involvement of the ON- bipolar cells (Fishman et al, Ophthalmology, 1996; 103: 96). Our patients, when specifically questioned, reported difficulty with night vision, but in no case was this the presenting symptom. The term acquired unilateral inner retinal dysfunction is proposed as a clinical description. 

TI	Multifocal VEPs in Normal Tension Glaucoma
AU	Kimura I
AU	Ohde H
AU	Tanino T
AU	Ohtake Y
AU	Betsuin Y
AU	Kita K
AU	Mashima Y
AU	Oguchi Y
AU	Hood D
IN	Keio University School of Medicine
AD	35 Shinanomachi Shinjuku-ku Tokyo, 160-8582 Japan
EM	kimura@mc.med.keio.ac.jp
AB	Purpose. To examine  the visual field of normal tension glaucoma (NTG) patients objectively, multifocal VEPs were recorded and compared with the results of Humphrey Visual Field Analyzer. Method. 15 NTG patients were tested. The  dartboard stimulus was used for recording with the VERIS Scientific System (Electro-Diagnostic Imaging, San Francisco,CA). Each of the 60 segments contains a black and white checkerboard pattern, which is alternated according to a binary m-sequence. Bipolar occipital straddle electrode positions were used.The visual field up to 25°of eccentricity was investigated.  The 1st slices of 2nd order  kernels of responses were calculated. One eye's responses were subtracted from those of the fellow eye,and the same procedure was followed with the data of the Humphrey Field Analyzer. Result. The multifocal VEPs corresponded well with Humphrey visual field defects, showing reduced amplitude in the scotoma area in 10 cases.There were 5 cases whose responses of VERIS did not correspond with Humphrey visual field defect. In these cases, the conditions of fixation were poor in 2 cases. One was a case iin which an  operation for rhegmatogenous retinal detachment was performed. The causes of discrepancy in the remaining cases were not clear.  Conclusion. These results show the possibility of  practical objective detection of  visual field defects in NTG using multifocal VEPs.

TI	A Case of Congenital Stationary Night Blindness (CSNB) with Previously-Undescribed ERGs. A New Entity?
AU	Kita K
AU	Shirao Y
AU	Kawasaki K
IN	Department of Ophthalmology, Kanazawa University School of Medicine,
Kanazawa, Japan
AD	13-1 Takara-machi, Kanazawa-shi, Ishikawa-ken 9208640, Japan.
AB	Purpose: To report an unusual case of CSNB. Methods: A 25-year-old man who had noticed night blindness from early childhood on, underwent ophthalmological examination including Goldmann perimetry, color vision test, dark adaptometry, routine full-field rod and cone ERGs and an ERG intensity series from the scotopic threshold response (STR). Results: He presented with normal visual acuity and mild myopia (-1.0
D). Ophthalmoscopic fundi, visual field and color vision appeared normal. Dark adaptometry revealed a normal time course and a depth for the rod-cone break and prolonged time course to the normal rod threshold. The conventional full-field ERGs showed extremely attenuated rod-ERG, normal cone-ERG and normal flicker-ERG. The cone-rod mixed single-bright-flash ERG (maximal response) showed the negative configuration typical of conventional CSNB. ERG intensity series showed a normal threshold and a normal peak time for the STR but markedly higher (1.7 log unit) threshold for the scotopic b-wave compared to our controls. Conclusions: These results suggest that the present case does not fall in any conventional categories of CSNB.

TI	Objective perimetry in glaucoma
AU	Klistorner, A
AU	Graham, SL
IN	Save Sight Institute,  Department of Ophthalmology, Sydney University,
AD	PO Box 4337, Sydney 2001, Australia
EM	sasha@eye.usyd.edu.au
Purpose: Objective perimetry in glaucoma has been described using the multi-focal pattern visual evoked potential (VEP).  A multi-channel recording  technique was utilised to improve signal detection in normals and assess its ability to detect glaucoma and early changes in suspects.Method: 35 normals, 32 patients with glaucomatous visual field defects and 30 glaucoma suspects were tested. The VEP was recorded using cortically scaled multi-focal pseudo-randomly alternated pattern stimuli with the VERIS system. An array of four bipolar occipital electrodes provided four differently oriented channels for simultaneous recording. Signals were compared for different locations within the field up to 26° of  eccentricity. Normals, glaucoma suspects and glaucoma patients with established visual field defects were tested and results compared to Humphrey visual fields performed on the same day. To assess reproducibility five normals were each tested on four separate days. In addition one glaucoma patient was tested 3 times over a two year period. Data from glaucoma suspects were analysed for inter-eye asymmetry  and compared to the asymmetry  values of normals. Results: Multiple recording channels significantly enhanced the recording of signals from parts of the visual field not reliably sampled with a single channel technique in all normal subjects, particularly along the horizontal meridian (p<0.001). Signal amplitude did not decline with age in normals. Recordings showed good reproducibility within individuals.  In all 32 cases of glaucoma the Humphrey visual field defects were well demonstrated by the VEP and topographic location was correlated strongly (r=0.72). Despite large inter-individual variations in amplitude, scotomas were well demonstrated when compared to normal values. In the glaucoma suspects, smaller changes in signal amplitude could be identified in parts of the field still normal on perimetry, using inter-eye asymmetry analysis.Conclusions: The multi-focal multi-channel VEP can objectively detect glaucomatous visual field defects. The nasal step region can be more reliably tested using multiple channels. Asymmetry analysis has the potential to detect early defects. This technique represents a significant step towards the clinical application of objective perimetry in glaucoma.	

TI	Supernormal ERG a-wave in birdshot chorioretinopathy; novel observations and the effect of treatment.
AU	Koh AHC
AU	Pavesio C
AU	Holder GE
IN	Moorfields Eye Hospital, City Road, London EC1V 2PD, England
AD	c/o Dr Marc Yoshizumi, Jules Stein Eye Institute, 200 Stein Plaza, UCLA, Los Angeles, CA 90095-7000
EM	ahckoh@yahoo.com 
AB	Purpose: To describe a case of birdshot chorioretinopathy with novel electroretinogram (ERG) findings. Methods: Serial ERGs (ISCEV standard) were obtained from a patient with birdshot chorioretinopathy. The first examination was performed prior to the onset of visual symptoms but at a stage when the fundus appearance was abnormal. Subsequent testing charted the progress of disease and the response to systemic corticosteroid treatment. Results: At first examination, ERGs from both eyes showed an electronegative waveform. Vision subsequently deteriorated and the a-wave in one eye became profoundly supernormal with an amplitude of almost 1000µV accompanied by no detectable b-wave. Following treatment, ERGs from both eyes improved. In one eye the ERGs became normal; in the other, although there was improvement, the profoundly supernormal a- wave remained. Treatment was therefore continued for a further six months after which the ERG in the second eye had also returned almost to normal. Conclusions:  This case report not only describes novel and remarkable ERG findings, but also illustrates the potential for the ERG to become an integral part of the overall management of patients with birdshot chorioretinopathy.

TI	Functional and structural assessment of the macula in solar eclipse maculopathy
AU	Kolkailah Karem A 
AU	Al-Nahrawy Osama MM
AU	El- Koumi Hamdi A
IN	Ophthalmlogy  Department, Suez Canal University, Egypt
IN	Ophthalmology Department, Tanta University, Egypt
EM	onahrawy@yahoo.com
AB	Objectives: The entire world witnessed the solar eclipse during August 1999. Warnings through out media against hazards of exposure to sun radiations were intense. The aim of this work is to study structural and functional damage in eyes with solar maculopathy.  Methods:  We recorded solar maculopathy in six eyes of three subjects. Macular structure, of eyes involved, was assessed using fundus photography and fluoroscein angiography. Laser measurements of the thickness of the macula were done using optical coherence tomography (OCT). Functional assessment was done using photopic and flicker ERG, flash and pattern reversal VEP and analysis of the central five and ten degrees of the visual field. Results: Photography revealed burns localized to the fovea of all eyes.  Intensity of these burns differed. Fluoroscein fundus angiography was unremarkable.  Macular visual field revealed central and paracentral points with reduction of sensitivity of five to six dB. VEP responses were within normal and similar in both eyes. ERG (ISCEV protocol) responses were within normal limits and similar in four eyes of two subjects. In the third subject, there was a significant difference between cone responses of the eyes, whereas the rod responses of the eyes were mirror images. OCT revealed macular thickening up to 300 microns in both eyes. Conclusion: Solar radiation can produce functional as well as structural damage for the macula. OCT and macular field were able to show structural and functional damage and were superior to fluoroscein angiography, full-field ERG and VEP.

TI	Visual evoked potentials simulation
AU	Kremlácek J 
AU	Kuba M 
AU	Holcík J 
AU	Vít F
IN	Charles University - Faculty of Medicine in Hradec Králové, Czech Republic
AD 	imkova 870, 500 01, Hradec Králové, Czech Republic
EM	jan.kremlacek@lfhk.cuni.cz
AB 	Purpose  We present an attempt to model an electrophysiological response to motion-onset and pattern reversal visual stimuli. Methods  On the basis of decomposition of the specified visual evoked potentials (VEPs) into three independent components (Kremláček J, Kuba M, Physiol. Res., 303-308, 1999) a three stage model was developed. The model consisted of serially connected non-linear second order damped oscillators of identical construction. The first oscillator was driven by the firing density of the lateral geniculate nuclei (Watson A, Nachmias J, Vision Res., 893-902, 1977). The model parameters were tuned for a particular stimulus by the Nelder-Mead simplex algorithm ( Lagarias JC et. al.,  SIAM Jour. Optim., 112-147, 1997). Results  The difference between the simulated signals and the VEPs (assessed by normalised root mean square error) was less than 12.9%, while an expected amount of a noise in the VEPs reached at least 13.2% (counted as ± average - Schimmel H, Science, 92-93, 1967). The switch from motion-onset to pattern-reversal generation was caused by doubling of the first two oscillators frequencies (from 7 and 4 Hz for motion to 15 and 7 Hz for reversal. The third oscillator, following slow changes in the VEPs, was dependent on the antecedent ones and it was tuned to 3 Hz or 1 Hz for motion and reversal respectively. The first oscillator contributed mainly to the pattern-reversal VEPs, while in the motion-onset the second one dominated. Three oscillators were activated at 29, 72 and 155 ms on average. Conclusions The proposed model seems to be a good approximation for a macroscopic electrophysiological manifestation of the brain processing of the used visual stimuli. Separated oscillators, along to the described parameters, reflect sequential activation of the primary (striate), secondary (extrastriate) and higher (cognitive) mechanisms.
Acknowledgements Supported by the Grant Agency of the Charles University, Czech Republic and by the James S. McDonnell Foundation for Cognitive Neuroscience, USA.

TI	Multifocal ERG recordings in patients with Leber`s hereditary optic neuropathy (LHON) 
AU	Kurtenbach A
AU	Leo-Kottler B
AU	Zrenner E
IN	University Eye Hospital, Department of Pathophysiology of Vision and
Neuro-ophthalmology
AD	Schleichstrasse 12-16, 72076 Tuebingen, Germany.
EM	anne.kurtenbach@uni-tuebingen.de
AB	Purpose: LHON is a maternally inherited disease that results in severe bilateral visual loss predominantly in otherwise healthy young men. It is associated with defined point mutations in the mitochondrial DNA.The aim of this study was to examine the multi-focal electroretinogram (m-ERG) in patients suffering from LHON, to obain information about the progression and etiology of the disease. Methods: The VERIS system was used to elicit m-ERGs. The stimulus geometry consisted of 61 hexagons which stimulated the central 30o of the retina. The luminance of the white hexagons was 100 cd/m2, that of the black 1.1cd/m2. Signals were amplified  (x200,000) and filtered (10-100Hz). First and second order kernel response components were analysed from 10 patients with molecularly defined mutations and their results compared to those of an age-matched control group. Results:  Amplitude reductions are found in most first order kernels in LHON patients, the size of the retinal area affected depending on the visual field of the patient. Latency increases are also found, although they appear to affect a larger retinal area than the amplitude reductions.  In general, changes in the second order kernel develop as the disease progresses.  Conclusions:  The alterations in the first order kernel indicate that outer retinal activity is affected early in  LHON patients. Mutations of the mitochondrial DNA may cause a reduction in the energy available for receptor.

TI	ERG and VEP in 2 siblings with Wolfram syndrome and a homozygous splice site mutation in the WFS1 gene.  
AU	Lorenz B
AU	Gerth C 
AU	Bock M
IN	Department of Pediatric Ophthalmology, Strabismology and Ophthalmogenetics,
University of Regensburg, Germany
AD	Franz-Josef-Strauß-Allee 11, 93042 Regensburg, Germany; 
EM	birgit.lorenz@klinik.uni-regensburg.de
AB	Purpose: To describe the ocular phenotype of a homozygous splice site mutation in the recently identified nuclear WFS1 gene (460, G-A, +1, Strom et al., Hum Molec Genet 1998) associated with Wolfram syndrome (DIDMOAD). Methods: The patients - a boy aged 17 yrs (TH) and his sister aged 19 yrs (TZ) from a consanguinous marriage - were examined clinically as well as by Ganzfeld ERG, MERG (first and second order kernel: FOK and SOK), flash VEP and pattern VEP. Results: In both patients, VA was severely reduced. Visual fields showed significant peripheral constriction with relative central scotomas. The lenses had spokelike opacities with otherwise normal anterior segments. There was temporal pallor of the optic disc, but also some RPE irregularities in the macula with otherwise normal retinae. Ganzfeld ERGs (ISCEV standard) were normal. The amplitudes of the FOK of the MERG were reduced and the latencies prolonged in the center only. Central changes in the SOK were also observed. Pattern VEP could be elicited in the boy only with prolonged latencies and reduced amplitudes. Flash VEP in the sister revealed reproducible responses on both sides. Conclusion: In contrast to a recent report on 45 patients with Wolfram syndome (Barrett et al., Eye 1997) both patients showed macular changes associated with circumscribed changes in the multifocal ERG which may indicate a retinal origin of the optic atrophy which is one of the features of Wolfram syndrome.

TI	Clinical observation  of EOG test in  central  chorioretinitis
AU	Lu Y  
AU	Bi S 
AU	Wang Q
AU	Tan S
IN	Ophthalmic Centre, Zhangjiabian Hospital,
AD	Zhongshan Guangdong 528436 China
AB	Objective: To conduct the EOG  test on 82 eyes in 73 cases of central chorioretinitis and observe the EOG changes before and after treatment. Methods: The 73 cases, in which patients are aged between 30 and 50 years, are divided into two groups according to the time in which symptoms are shown. 45 eyes in 45 cases are classified into the first group. Patients in this group have shown symptoms for 3 to 15 days. EOG test discovers:  Dark trough potential ( DTP ) increases in all cases with a  notable  increase in  10 cases; Light peak potential ( LPP ) rise in 10 cases, remains normal  in 25 cases and falls in other 10 cases; Arden  ration drops in 30 cases and  remains normal in the remaining 15 cases.  37 eyes in  28 cases belong to the second group. Patients in  this  group have shown symptoms for 30 to 45 days. EOG test shows: All eyes suffer notable drop in both DTP and  LPP; even the fellow eye of the patients in five cases suffers a drop of different degree in the above-mentioned items; only six  cases indicate a decrease in Arden ration while others  show abnormal values. Results:  EOG test after 30 days of medication shows the following: In the first group, 18 cases, of the total return to normal with patients' eyesight improving to 1.0 and symptoms having disappeared;  27 cases witness improvement with eyesight ranging between  0.6 and 0.8 and vision distortion having eased. In the second   group, improvements of different degree have been  seen in the  patients with Arden ration remaining within the normal  range  and  eyesight getting better.  Conclusion:   In EOG test of early central chorioretinitis patients, DTP shows a marked increase and Arden ration shows  a  marked increase and Arden ration shows abnormality. DTP  and LPP also indicate a noticeable drop while Arden ration may remain normal. Patients usually present after symptoms have shown for quite period of  time. EOG test can provide objective indexes which can be  used  in patients' clinical treatment and rehabilitation.

TI	Does adaptation or room lighting affect the multifocal ERG?  
AU	Marmor MF
AU	Chappelow AV
IN	Stanford University
AD	Department of Ophthalmology, A-157, Stanford, CA 94305-5308
EM	marmor@stanford.edu
AB	Purpose:  To evaluate the effects of pre-adaptation, room-illumination, and background screen luminance on the multifocal ERG (MERG).  Methods:  MERGs were recorded with a VERIS System using EDI Scientific software.  Recordings were made using Burian-Allen electrodes, and 61 or 103 hexagon stimulus arrays with a mean luminance of 100 cd/m2.  Normal volunteers (n=22, average age 32) had sequential MERGs recorded under different conditions of lighting and adaptation.  Results:  Changing pre-adaptation conditions between darkness for 20 min, or light at 27 cd/m2 for 10 min, had essentially no effect on the MERG, regardless of ambient room lighting.  There was also no difference between MERG results with a background screen luminance (i.e., surrounding the stimulus) of 50 or 100 cd/m2.  However, the MERG was quite sensitive to the level of room illumination.  A-wave and b-wave amplitudes were maximal in very dim lighting (≤ -1.25 log cd/m2) and fell by roughly 25% when the room luminance was raised above 0.5 log cd/m2.  The b-wave time-to-peak also diminished with increasing illumination.  These effects were observed in both central and peripheral regions of the macula.  Conclusions:  The MERG is largely independent of pre-adaptation conditions and background screen luminance, but waveform amplitudes and time-to-peak diminish with increasing levels of room illumination.  We suggest that average room illumination be ≤ -1.25 log cd/m2 to maximize MERG response amplitude and minimize variability.

TI	Value of Oscillatory Potentials in Diabetic Patients
AU	Massoud W
IN	Ophthalmic Department, Minia Univerity, Minia, Egypt
AB	Objectives To determine if oscillatory potentials (OPs) can play a role in detection of diabetic retinopathy, before detection by fluoroscein injection or other clinical methods. Methods: We used the UTAS system in two ways: The flash ERG with the low cut filter of the amplifiers set to 75Hz, and then the flash ERG was measured with the low cut filter set normally and the software filtering system was used to extract the OPs.
Forty diabetic patients attending ophthalmic and medical outpatient clinics of the University Hospital were selected to represent our sample; they had the following criteria:
•	17 male, 23 female patients
•	Ages ranged from 23- 69 years
•	Duration of diabetes duiagnosis ranged from a few months to more than 10 years
•	20 patients (40 eyes) had NO fundus changes neither ophthalmoscopically or by fluorescein angiography.
•	20 patients (37) eyes) had different stages of retinopathy either ophthalmoscopically (by fundus examination) or by fluorescein angiography
Results:  In the group with no fundus changes, OP values were significantly lower than control values, ranging from 50-61 v compared to the minimum normal value of 75 v. In the group with fundus changes, OPs were absent in more than 50% of patients, while in the other 50% values were too low to be compared with the control group or with the first group. Conclusion: OPs proved to be a useful diagnostic tool for early detection of cellular retinal hypoxic insult in diabetic retinopathy.

TI	Acquisition and Implementation of a Commercial Visual Electrophysiology System. 
AU	McLaren TL
AU	Atkinson JM
AU	Bottomley MR
AU	Chelva E
AU	De Roach JN
AU	Fisher RH
AU	Kay SMS
AU	Price RI
IN	Department of Medical Technology and Physics, 
AD 	Sir Charles Gairdner Hospital, Perth, Western Australia
EM	terri@mtp.pd.uwa.edu.au
AB	Purpose: To describe the acquisition and implementation of a commercial visual electrophysiology system by a department with over 20 years experience in providing visual electrophysiology services. A primary objective of the new system was to provide electrophysiological testing in full accordance with ISCEV standards. Methods: We surveyed Australian users of various electrophysiology systems regarding selection, purchase, performance, technical support, and adherence to ISCEV standards. Tenders were invited and the LKC UTAS-E 3000 Visual Electrophysiology System was subsequently purchased. Implementation was planned to include photometry, system calibrations, interfacing to the departmental network, writing of software for report production to our standard and the collection of normal data. A hospital ethics committee approved project has been established to collect age based normative data on approximately 80 individuals for EOG, ERG, PERG and VEP. Results: Hardware and software faults have arisen continuously for fifteen months post-installation requiring many hours of in-house technician time and a number of component replacements.  Soon after the apparently successful installation we experienced unacceptable 60 Hz contamination of VEP and PERG data which we overcame by replacing the supplied pattern generator monitor with one of superior quality. The ganzfeld unit has generated a number of faults, and both the ganzfeld flash unit and power supply have been replaced. Photometric measurements revealed low and unstable background light levels necessitating replacement of the lamp housing. Other faults have included system start-up taking 15 minutes and various system failures. The computer boards have consequently been reseated. Filter board failures have resulted in boards being replaced on two occasions.  At 12 months post-installation an extended warranty period of a further 12 months was negotiated. Conclusions: It is essential to thoroughly investigate the exact model, in operation by experienced users, of any system under consideration for purchase.  Spare parts and technical support must be locally available. However, this implementation process gave us the opportunity to examine and re-evaluate our work practices such that we are confident that when the system is operational to our requirements our visual electrophysiology services will be fully ISCEV compliant.

TI	The P50 and N95components of the pattern-ERG show different naso-temporal a	symmetries
AU	Meigen, T
AU	Heine, H
IN	Dr. T. Meigen, Universitaets-Augenklinik, Josef-Schneider-Str. 11,D-97080 Wuerzburg, Germany
EM	t.meigen@augenklinik.uni-wuerzburg.de
AB	Purpose: It is known that the nasal retina has a higher ganglion cell density than the temporal retina [1]. However, there arecontradictory findings concerning the existence and direction ofnaso-temporal asymmetries in PERG recordings.We asked (a) whether the P50 and N95 components of the transient PERG show similar naso-temporal asymmetries, and (b) whether these asymmetries may be explained by the difference in ganglion cell density. Methods: 50 visually normal subjects participated in the experiment. Checkerboard patterns with a checksize of 0.8˚, a contrast of 100%, and a mean luminance of 40 cd/m^2 were presented within a stimulus field of 36˚• 27˚. The stimulus field was divided horizontally in two hemifields of identical size. Reversal ofthe stimulus patterns was performed separately for the two hemifields.Transient PERG responses (f = 2.2 Hz) were recorded binocularly with DTL electrodes. Amplitude and latency values of the P50 and N95 components were estimated for further analysis.Within each subject, we averaged both the nasal and the temporal components across both eyes. Paired t-tests were performed to obtain the statistical significance of naso-temporaldifferences. Results: While no significant differences were foundfor the P50 amplitude, the N95 of the temporal hemiretina showed largeramplitudes than the nasal hemiretina. In contrast, significant latency differences wereonly found for the P50, but not for the N95.
Mean±SEM(n=50)	P50 Amplitude	P50 Latency	N95 Amplitude	N95 Latency
Nasal			2.92±0.13µV	54.0±0.4 ms	3.23±0.13 µV	100.8±0.9 ms
Temporal		2.81±0.13µV	52.4±0.4 ms	4.08±0.18 µV	100.5±1.1 ms
Significance		p=0.14		p<0.0001	p<0.0001	p=0.79

Conclusions: (a) The P50 and N95 PERG components show different naso-temporal asymmetries. This may reflect different generators for theP50 and N95 components. (b) PERG amplitudes can not be linked to ganglion cell density in a simple way. The larger number of ganglion cells in the nasal hemiretina does not lead to an increased P50 amplitude, while the N95 amplitude is even reduced compared to that of the temporal hemiretina.
[1] Curcio, CA & Allen, KA (1990) Topography of Ganglion Cells in Human Retina. J Comp. Neurol. 300:5-25

TI	Importance of electrophysiological investigations in preoperative evaluation of the retina, vitreous and optic nerve.
AU	Meller, M
AU	Bernardczyk-Meller, J
AU	Rynarzewska, E
AU	Pecold, K
IN	Department of Ophthalmology, Karol Marcinkowski University of Medical Sciences, Poznan, Poland
AB	Objectives: The aim of the study was to estimate the importance of results of electrophysiological investigations in patients with vitreoretinal disorders and traumatic cataract. Methods: Full ophthalmological examinations, and electrophysiological and ultrasound investigations were performed in 40 patients (9 females and 31 males, aged from 24 to 52 years, average age 36.5 years). The patients were divided into three groups: A) 8 patients with cataract, B) 18 patients with long-lasting retinal detachment, C) 14 patients with diabetic retinopathy and/or retinal detachment and/or vitreous haemorrhage. The electrophysiological investigations consisted of: pattern-reversal visual evoked potentials –p VEPs, flash visual evoked potentials – fVEPs, scotopic and photopic electroretinogram (ERG) and were performed with Toennies Multiliner Vision equipment. The electrophysiological results were analysed and compared to the results of a normal control group. Results: In all patients with traumatic cataract normal shape and parameters in fVEPs pointed to good visual acuity after surgery. In patients in group B, the ERG parameters were greatly reduced because of the long period of the disease. Pathological VEPs results suggested the possibility of ischemia of retina and optic nerve in this group. In most patients in group C), the function of the retina and optic nerve were reduced. We observed the improvement of the visual acuity after successful vitreoretinal surgery over a period of  3-6 months. In these cases the function of the retina and optic nerve was at least 20% compared to control group. Conclusions: Electrophysiological investigations have great value in ophthalmological surgery, especially in eyes with opaque media. They give much information to the surgeon and to the patient before surgery. In selected cases they also may help in explaining poor function of the visual system after surgery. Pathological results of electrophysiological investigations were major reasons for leaving eyes untreated.

TI	Flash and pattern ERG's in Stargardt's disease
AU	Mitchell KW
AU	Clarke MP
IN	Regional Department of Medical Physics & University Department
	of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne
AD	University Department of Ophthalmology, Royal Victoria Infirmary,
	Newcastle upon Tyne NE1 4LP   UK
EM	K.W.Mitchell@ncl.ac.uk
AB	Purpose: To investigate the Flash ERG and pattern ERG in a cohort of patients with Stargardt's disease. Methods: Eleven patients were studied using standardised approaches (ISCEV ERG Standard 94, ISCEV PERG Guidelines 96) and compared to
Laboratory control data elicited under the same conditions. Results: All showed some form of electrophysiological abnormality, 9 of  the 11 (82%) in relation to the FERG and 9 of 9 (100%) in the PERG. The predominant effect was amplitude reduction but implicit time effects were observed in both responses also. Conclusion: Stargardt's disease not only affects macular function as signalled by the PERG but also panretinal function as declared by the FERG. The  temporal progression of events in the photoreceptor- midretinal layer complex also appears likely to be compromised.

TI	A case with neuroretinopathy caused by heavy charged particle irradiation 
AU	Mizota A# 
AU	Suehiro S#
AU	Adachi-Usami E# 
AU	Mizoe J*
IN	Department of Ophthalmology, Chiba University School of Medicine, Japan#, National Institute of Radiological Science, Chiba, Japan* 
AD	Department of Ophthalmology, Chiba University School of Medicine, 1-8-1 Inohana Chuo-ku, Chiba, 2608670, Japan
EM	mizota@ophthalm.m.chiba-u.ac.jp
AB	Purpose: Heavy charged particles have begun to be used to treat certain kinds of malignant tumors such as malignant melanoma.  To date, no case with ocular side effects have been reported.  We wish to report the funduscopic, fluorescein angiographic and electrophysiologic findings in a patient with squamous cell carcinoma before and after treatment with heavy charged particle irradiation which resulted in a neuroretinopathy.  Case and Results: A forty-seven-year-old man was diagnosed with squamous cell carcinoma of the paranasal sinus in September, 1997. The tumor originated from the ethmoid sinus and invaded the left orbit, frontal sinus and maxillary sinus.  He underwent chemotherapy but no significant improvement was seen.  Heavy charged carbon particle irradiation therapy was then applied from January 23 to February 20, 1998.  Totally, the tumor including the optic nerve and retina of his left eye was irradiated with 16 Gy.  Ocular examination and electrophysiological examination before and 1, 6, 12 months after the therapy did not reveal any abnormalities except for myopic fundus changes.  In April, 1999, 15 months after the irradiation, the patient noticed a decrease of vision in his left eye.  On April 26, 1999, his best corrected visual acuity  was 0.8 and cotton wool patches were seen around the left optic disk.  Fluorescein angiography revealed prolonged circulation time in the choroid and optic disk.  P100 peak latency of the pattern VECP was prolonged from 120 to 140 ms. The amplitudes of the a- and b-wave of single flash ERGs were normal.  On May 26, the vision in his left eye decreased to hand motion and retinal arteries were almost occluded.  The amplitudes of both a- and b-wave of single flash ERG were markedly decreased. Conclusions: Both the retina and optic nerve were damaged by 16 Gy of heavy charged carbon particle irradiation therapy.  The changes in his retina and optic nerve were similar to retinal and optic nerve changes induced by X-ray irradiation. The P100 peak latency of PVECP was delayed even at the early stage of the disease.

TI	A Trial of Objective Visual Field Measurement By Pupillary Reaction
AU	Mizukawa K
AU	Tabuchi A
IN	Department of Ophthalmology, Kawasaki Medical School, Okayama, Japan
AD	577 Matsushima, Kurashiki-city, Okayama 701-0192, Japan
EM	mike@med.kawasaki-m.ac.jp
AB	Purpose: All enforced visual field tests depend on a subjective reply. Because subjective replies are vague in small children and / or non-cooperative patients, the reliability of such tests in there patients becomes low. If we could measure a visual field objectively, it would be very useful for these patients. In this experiment, we produced a pupil perimetry created by the Visual Evoked Response Imaging System (VERIS) and an infrared pupillometer, and investigated its clinical application. Methods: We examined 10 normal volunteers (mean age; 26 y.o.) under three kinds of room illumination; i.e., room light, 5 asb and dark, with a stimulus intensity of white (100cd/m2) - gray (20cd/m2), and a stimulus frequency of about 2 Hz.  The 19 elements for ERG according to the Veris Science 4.1 were used for stimulation on a central 15-degree visual field. To establish a suitable stimulus intensity, we also examined 22 normal volunteers (mean age; 38.0 y.o.) with a condition of white (100cd/m2) black (0cd/m2) and white – gray with room illumination of 5 asb. The wave patterns obtained were analyzed with the Veris Science 4.1, and changes in the amplitude of the maximum diameter of the pupil and coefficient variations were calculated. The stimulated area was divided into three parts; i.e., central, midcentral and peripheral, and was also divided into four quadrants; superior-temporal, superior-nasal, inferior-temporal and inferior-nasal. For pathological conditions, we examined six hemianopia patients (mean age; 52.0 y.o.). Results: The smallest coefficient variation was obtained under the condition of room illumination of 5 asb (central; 23.3% ~ peripheral; 34.7%), and the stimulus intensity of white-black (central; 21.0% ~ peripheral; 29.5%). Pupil responses tended to be biggest in the superior-temporal quadrant, and smallest in the inferior-nasal quadrant. In the hemianopia patients, the pupillary responses in the blind field were deteriorated as compared with those of the normal field. Conclusions: At least in the central area within 15 degrees, the objective perimetry of pupillary responses is clinically applicable. Further study is necessary, however, for an ordinary visual field test, which requires a wider range field. 

TI	Visual function of three cases with intraocular tumor
AU	Morimoto K
AU	Yoshii M
AU	Okisaka S
IN	Department of Ophthalmology, National Defense Medical College
AD	3-2 Namiki, Tokorozawa-shi, Saitama-ken, 359-8513 Japan
EM	masaruy@mb.infoweb.ne.jp
AB	Purpose: To study the electrophysiological function of three cases with intraocular tumor (retinal cavernus hemangioma, melanocytoma and tuberous sclerosis). Methods: Multifocal electroretinogram (ERG), pattern ERG and pattern visual evoked potential were recorded from these three cases. Multifocal ERGs were elicited using the Veris III system (Mayo Corporation).The stimuli consisted of densely arranged arrays of 103 hexagonal elements. The pupils were fully dilated and a bipolar contact lens electrode was used. It took 4 minutes to obtain one mERG record. Pattern stimulation was done using a checkerboard pattern (34min of arc check, 3rev/s, 95%contrast, 43.1cd/m2 mean luminance). 300 signals were summated. The high cut and low cut filters were 50 Hz and 1Hz, respectively. Case 1: 44 year-old male. Retinal cavernus hemangioma. Case 2: 54 year-old male. Melanocytoma. Case 3: 25 year-old male. Tuberous sclerosis. Results: Pattern ERG responses were reduced more than multifocal ERG responses in these cases. A delay in pattern VEP latency was more pronounced for tuberous sclerosis. The central visual field abnormality was detected in the melanocytoma case. A discrepancy was observed between the Humphrey data and the electrophysiological findings. However, SLO examination revealed no abnormal subretinal vessels around the optic disc of the affected eye. Conclusions: Multifocal ERG, pattern ERG and pattern VEP are useful clinical tools for understanding the visual function in the cases of the intraocular tumors, when the other ophthalmic findings are evaluated together with the electrophisiological data.

TI	Multi-focal ERG in retinal detachment surgery 
AU	Moschos, M
AU	Malias, J  
AU	Theodossiadis, G 
IN	Ophthalmology Department, Athens University. 
AB	Purpose  To investigate whether the Multi-focal ERG can be helful in clinical practice for following the evolution of retinal function in eyes operated  for retinal detachment. Method For the multi input technique a stimulus pattern consisting of 61 hexagons were presented by a VERIS program  in a computer system  (Tomey Nagoya, Japan). MF ERG was recored in  eyes suffering from retinal detachment operated on by a Lincoff Custodis method. All the eyes had a visual acuity  20/20. Results  The peripheral  scotoma due to retinal surgery is monitored better and more accurately than by the classical methods of monitoring the visual fields. Conclusion   Multi-focal ERG is an objective and credible tool  in clinical practice for monitoring and quantifying the functional abnormalities affecting the peripheral vision in eyes operated  for  detachment of the retina.

TI 	Pigmentary retinopathy with leopard-spot pattern of unknown etiology
AU 	Nakamura.T
AU	Miyauchi.O
AU	Mizota.A
AU	Adachi-Usami.E
IN	Department of Ophthalmology, Chiba University School of Medicine,Japan
AD 	Inohana 1-8-1,Chuo-ku,Chiba  260-8670,Japan
EM 	Taniai＠ophthalm.m.chiba‐u.ac. jp
AB 	Objectives :To report a patient with pigmentary retinopathy with leopard-spots on the whole retina of both eyes which has never been observed in the past.  Subject and methods : A 76-year-old man referred to our clinic to have an ophthalmic examination before receiving hemodialysis therapy, though he had no visual complaints.  The patient was diagnosed for 2 years as chronic nephritis after suffering from hypertension. In the past, no chemotherapic agents have been received.  And no history of eye complaints. Funduscopic examination of both eyes disclosed freckle-like brown pigment diffusely scattering from adjacent to the optic disc to the periphery on the whole retina.  The fluorescein angiography demonstrated window defects that reflected a severe loss of the retinal pigment epithelium and choriocapillaris.  The pigmentary spots were very similar to a leopard-spot pattern seen in uveal effusion. Visual acuity was 0.3 right eye and 0.3 (0.4) left eye.  Both photopic and scotopic electroretinograms (ERG) were abnormal,  i.e. both a- and b-wave reduced to half of normal values, while pattern visual evoked cortical potentials were normal.  Dark adaptometry showed an increase of approx.1.0 log unit in the rod curve. Goldmann perimetry revealed normal.  Conclusions : The leopard-spot pattern of pigment clumping seen in our patient with chronic nephritis is a new observation.  The case revealed a decrease of both scotopic and photopic function by ERG, while the optic nerve function was proved to be normal by VECPs.  The patient could be a new type of atypical retinitis pigmentosa. The mechanism of the retinopathy is uncertain.

TI	Retinal function after panretinal photocoagulation in diabetic patients assessed by electroretinogram             
AU	Ohn YH
AU	Han YK
IN	Department of Ophthalmology, Soonchunhyang University Hospital
AD	657-54 Hannam-Dong, Yongsan-Ku, Seoul, Korea  140-743
EM	yhohn@hosp.sch.ac.kr
AB	Purpose To evaluate the effect of panretinal photocoagulation(PRP) on the
electroretinogram, comparing the anatomical and functional changes of retina after PRP. Methods Retrospective study was performed on 58 eyes of 29 patients with  proliferative diabetic retinopathy(PDR) who underwent panretinal  photocoagulation. Fluorescein angiography(FAG) and electroretinograms(ERG) were examined in each patient before and after PRP. ERG results after PRP(mean 2.4 months) to one group of 38 eyes showing obvious new vessels regression and  the other group of  20 eyes showing poor regression were compared. Results  Marked reduction in amplitude and delay in implicit time were observed in all the patients in which b-waves were more reduced than a-waves. There were no significant differences in ERG changes after PRP between the two groups(p>0.05). Conclusions These results suggest that PRP treatment in diabetic patients may affect the whole retinal layers. However, ERG is not a good indicator for the regression of retinal neovascularization. PRP treatment may recover the anatomical  integrity, but not  correct the functional impairment of retina

TI	Multifocal electroretinogram in occult macular dystrophy
AU	Piao, C-H
AU	Kondo, M
AU	Tanikawa, A
AU	Terasaki, H
AU	Miyake, Y
IN	Department of Ophthalmology, Nagoya University School of
Medicine.
AD	65 Tsuruma-cho, Showa-ku, Nagoya 466, Japan.
EM	piao@med.nagoya-u.ac.jp
Purpose. Occult macular dystrophy (OMD) is an unusual macular dystrophy presenting with an essentially normal fundus and fluorescein angiography but with progressive central visual loss.The diagnosis is made by the normal full-field ERG with the abnormal focal macular ERG. We studied the function of local retinal areas in the posterior pole of patients with OMD using multifocal ERG. Methods. Multifocal ERGs were recorded using the Visual Evoked Response Imaging System with 61 hexagonal elements within a visual field of 30 degrees radius from 8 OMD patients and 20 age-matched, normal subjects. The amplitudes and implicit times of the patients and normal controls were compared at the various retinal eccentricities. Results. The amplitudes of the multifocal ERGs in the OMD patients were markedly reduced in the central 7 degrees of the fovea. The difference of the ERG  amplitudes between OMD and normals became smaller towards the peripheral retina. Most OMD patients had slight but significantly delayed implicit times across whole testing field and the differences between the OMD and
the normals did not change with retinal eccentricity.  Conclusions. Our results for multifocal ERG amplitudes support the idea that OMD patients have localized retinal dysfunction distal to the ganglion cells in the central retina. The delayed implicit times across the whole test field suggest that the retinal dysfunction has a broader boundary than expected by ERG amplitudes and psychophysical perimetric results.

TI	Pattern erg in relation to kinetic and static perimetry and visual acuity in retinitis pigmentosa
AU	Popovic, P 
AU	Jarc-Vidmar, M
AU	Brecelj, J
AU	Hawlina, M
IN	University Eye Clinic and University Institute for Clinical Neurophysiology
AD	Ljubljana, Slovenia
AB	Objectives: We have previously shown (ISCEV 1996,1998) that pattern ERG has its diagnostic value in testing the progression of retinitis pigmentosa when flash responses are already absent. This study was conducted to determine how PERG, reflecting the activity of inner retinal layers that are least affected in retinitis pigmentosa, is related to visual acuity and the extent of remaining visual field. Methods: An analysis was performed on 50 eyes of 25 patients with rod-cone retinitis pigmentosa. Transient pattern ERGs were elicited by checkerboard pattern projected onto translucent screen of 16° r reversing at 1.6 Hz and recorded simultaneously from both eyes by HK-loop electrodes. Responses were averaged and analyzed using a Nicolet MS 2000 system. Flash ERG responses were measured according to ISCEV standards. Visual field sensitivity using Octopus M2 and Goldmann (II4e, V4e) was tested. Amplitudes of PERG P50 and N95 were compared to results of visual acuity and visual field testing. Results: In our group of RP patients with visual acuity ranging from 0.2 to 1.0, PERG responses were preserved much better than full field ERGs. Out of 50 eyes, 32 of them had still recordable PERG responses, while 24 had cone and only 16 maximal responses. Scotopic rod responses were absent in all eyes. All patients with preserved PERG responses had visual acuity 0.4 or better. A strong correlation of both P50 and N95 amplitudes with Octopus mean defect was found (r = -0.76, r = -0.68, respectively). In kinetic perimetry the correlation with PERG amplitudes was also moderately high, and it was better with II4e than with V4e target. A linear agreement between visual acuity and PERG amplitudes was also found, PERG responses disappearing at visual acuity of 0.3 or less. Conclusions: Amplitudes of both PERG P50 and N95 are linearly related to the remaining functional retina in patients with rod-cone retinitis pigmentosa. The agreement can be found in patients with good visual acuity (better than 0.3) and is more pronounced in static than kinetic perimetry. Pattern ERG can therefore be used as a sensitive test in evaluating the functional visual loss in retinitis pigmentosa.

TI	A kinetic model of the contribution of the rod photocurrent to the electroretinogram
AU	Robson, JG 
AU	Frishman LJ
IN	College of Optometry, University of Houston, TX 77204,  USA
EM	Jgr11@cam.ac.uk 
AB	Purpose To provide a model that describes the entire timecourse of the rod contribution to the electroretinogram (ERG).  Specifically, this model should describe the early part of the a-wave as well as the later timecourse of the rod response (derived P3) as determined using the high energy probe-flash technique introduced by Birch et al.(1995).   Methods  ERG responses to brief flashes with luminous energies between 0.3 and 700 scot td.s were recorded from anaesthetised macaque monkeys and cats.  The timecourse (to 600 ms) of the rod response to the weaker flashes  was determined using a probe-flash of about 15000 scot td.s. Results  The basis of our proposed  model is the assumption that the rod photoresponse results from compression by an instantaneous nonlinearity of a signal generated by a linear mechanism.   In this respect, as well as in the formulation of the basic response of the linear mechanism, our model can be considered to be a modification of Hetling and Pepperberg’s (1999) model for the mouse.  However, to obtain good fits to our data without introducing a time-dependent gain factor, we have modified their model so that a) the linear system includes an extra low-pass filter element with a time constant of 15 to 20 ms, b) the non-linear characteristic is modeled as a weighted sum of exponential and hyperbolic functions (making the saturation less abrupt than a simple exponential function) and c) the transport delay is reduced to < 1ms (from about 3ms).  Conclusions We have generated a model that provides a good description of both the early (<10ms), low amplitude (< two-thirds maximum) portion of ERG a-waves and the complete time course of derived P3 to flashes of all  energies studied. This model describes the response, r(t), of the rods by 
r(t) = rmax{F[1‑exp(‑s(t))]+(1‑F)s(t)/(1+s(t))},  0>F>1 and
s(t) = {kI[1‑exp(‑(t‑td)2/TE2)]exp(‑t/TR)}*exp(‑t/TX),  t>td
where rmax is the maximum response, F determines the abruptness of the saturation, td is a transport delay, k is a constant, TE and TR characterise the time of excitation and recovery and TX is an additional time constant. The * indicates convolution. This model should improve our ability to analyse the ERG into its basic components and provide a better estimate of the timecourse of the signal transmitted from rods to bipolar and more proximal cells. 
References Birch, Hood, Nusinowitz & Pepperberg (1995) IOVS 36,1603-1614;  Hetling & Pepperberg (1999) J. Physiol. 516.2, 593-609.
 
TI	A multi-channel and shape-independent detector for multi-focal visual evoked responses in objective perimetry
AU	Schellhorn, K.
AU	Schlegelmilch, F.
AU	Henning, G.
IN	Department of Biomedical Engineering, Ilmenau Technical University
AD	P.O.Box 100 565, D-98684 Ilmenau, Germany
EM	ksc@informatik.tu-ilmenau.de
AB	Purpose To detect the monoocular visual field an objective perimetry based on the local stimulation of the retina and the recording of the visual evoked responses (VER) should be developed. Since the VER gives very weak signals their shape and projection over the visual cortex varies. Considering this a multi-channel and shape-independent detector is required. Methods The retina is stimulated multi-focally by white LED flashes inside a visual field of 60 degree using the sparse stimulation technique of M-sequence stimulation. The EEG is recorded over the cortex using an array of 32 electrodes. From the raw EEG at each channel an M-sequence matrix is read out synchronously to the beginning of the inter-stimulus interval. Each resulting realization of the M-sequence matrix is normalized, filtered and transformed to normal scores before weighting by the M-sequence coefficients and averaging over all realizations. Thereby the inter- and intra-individual variability during EEG recording can be reduced significantly. Further, the transformation to normal scores allows a comparison of empirical and theoretical test statistics. Results The global field strength and the topography of first and second order kernels are highly dependent on the stimulus location. From non-stimulated EEG data of 10 volunteers a reference of over 300000 quasi-independent samples is found resulting in a Chi-square distribution with one degree of freedom after squaring the values. Considering the length of the applied filters a sensible combination of quasi-independent samples over the relevant time-range increases the degrees of freedom of the Chi-squared distributed test values according to the theory. If a VER is present the quadratic test values show significant deviation from the distribution of the non-stimulus reference data. Thus signal (VER) and noise (no VER) can be distinguished statistically. Conclusions Amplitude and latency as a reference for cortical M-sequence VER can only be used within small stimulation areas where the projection at the cortex is approximately the same. If a large visual field should be scanned simultaneously, the use of a shape and projection independent detector becomes necessary. The proposed method allows the investigation of different parameters of M-sequence stimulation like size and luminance of the LED, background luminance, the length of the M-sequence, the on-time of the stimulus and the inter-stimulus interval with regard to achieve a sufficient SNR for perimetric investigations. Furthermore, an electrode combination can be derived allowing a reliable detection of VER inside a visual field of 60 degree using only four electrodes.

TI 	Assessment of the degree of amblyopia in children with partial cataracts
AU 	Shpak AA
IN	IRTC "Eye microsurgery"
AD 	Beskudnikovsky blvd., 59-A, Moscow 127486 Russia
EM 	A.Shpak@g23.relcom.ru
AB 	Purpose. The goal of this study was to develop the method for the assessment of the degree of amblyopia in children with partial cataracts. Methods. Pattern-reversal visual evoked potentials (VEP) elicited by 4 patterns of different checksizes (60’ and 20’) and contrasts (90% and 30%) were used for the rough evaluation of contrast sensitivity at low spatial frequencies. VEP were registered in 60 children (96 eyes) with partial cataracts (55 eyes) or stimulus deprivation amblyopia after cataract extraction (41 eyes) and 41 controls. Results. Three ‘types’ (degrees of deterioration) of VEP were established in patients with stimulus deprivation amblyopia after the cataract extraction. In VEP of type I all 4 evoked responses were present but could be of slightly decreased amplitude. In VEP of type II 1 or 2 responses were absent and in type III only pattern of 60’ checks and 90% contrast evoked the VEP. A direct relationship was found between the VEP types and the degree of amblyopia (the degree of visual acuity loss). Similar relationships were established in patients with cataracts of different intensity (slight or pronounced). Conclusions. The proposed VEP-method might be useful in objective evaluation of the degree of amblyopia in children with partial cataracts.

TI	Functional peripheral visual performance in patients with RP 
AU	Seiple W 
AU	Holopigian K
AU	Carr RE
IN	New York University School of Medicine, Department of Ophthalmology
AD	550 First Ave., New York, NY 10016.
EM	whs4@is3.nyu.edu
AB	Purpose. To assess peripheral electrophysiological responses and psychophysical function for detection, discrimination, and identification in patients with RP.  Methods. Ten patients with RP who had >20/40 visual acuity were studied. Psychophysical performance was assessed on the following tasks: grating acuity, grating contrast sensitivity, grating discrimination and letter identification at eccentricities from 0o to 20o in the temporal retina.  Also, cone multi-focal ERG responses (103 hexagons; 0F condition) and Humphrey visual field thresholds were obtained for the same retinal areas. Results. Peripheral thresholds were closer to normal values (lower thresholds and larger field area) for grating discrimination than for letter identification thresholds or for Humphrey visual field thresholds. Peripheral performance was poorest for grating acuity and grating contrast thresholds. Multi-focal ERG responses were markedly abnormal in amplitude and timing at many retinal locations where psychophysical performance was normal or near normal. Conclusions. When assessing peripheral performance in patients with RP, responses to functional tasks may show less impairment than indicated by detection tasks such as Humphrey visual fields or by local electrophysiological responses.

TI	Severe amblyopia – what is it?
AU	Shamshinova AM
AU	Mosin IM
AU	Krivosheev AA
AU	Barseghyan HL 
AU	Dvorianchikova AP
IN	Moscow Helmholtz Research Institute of Eye Diseases
AD	Moscow, Russia, Sadovaja-Chernogrjasskaja 14/19
EM	diblag@cityline.ru
AB	Purpose: To study why visual functions do not improve in patients with "severe" amblyopia, in spite of treatment. Methods: 20 children aged from 4-7 years with severe amblyopia were investigated. Visual acuity was reduced from the birth on one or both eyes ( 0.3-0.03) in these patients. These patients had a history of perinatal complications etc. The fundus of the eye as a rule was normal. Ganzfeld ERG, local ERG and VEP were used to examine the visual system. VEP maps, and localization of bioelectrical source activity were realized using a computer program "Brainlock"(MBN, Russia). Spatial contrast sensitivity, colour vision and on/off-activity of the cone system research were realized by using original computer programs, and a high resolution color monitor. All functional data were compared with results of  computed tomography and magnetic resonance imaging. Results: A range of refractive errors was found. Ganzfeld and local ERG were normal or slightly reduced and color sensitivity was considerably reduced for red and green. Most of the patients had reduced on/off-activity  both for light  (on), and for dark (off) channels in comparison with normal subjects. The spatial contrast sensitivity was  reduced throughout the range of frequencies in both eyes with large losses at high spatial frequencies, and reductions at low and middle spatial frequencies. The source of bioelectrical activity was absent in the occipital lobe or was poorly expressed in the contralateral occipital lobe  in patients with "severe" amblyopia. All the patients had changes in the VEP: they had poor responses to patterns with 7-55 min check sizes, with increased latency and decreased amplitude of the P100 component. The dominant activity was  not in the occipital lobe, but was shown in other areas of the brain (hypothalamus, parietal and frontal lobe). These findings suggested abnormal processes in the area of the calcarine sulcus. Magnetic resonance imaging showed congenital brain malformation or diffuse brain tissue loss in different areas in 15 of these patients. Conclusion. Impaired development of the central visual pathway, of various causes, was present most of these cases with "severe amblyopia".

TI	The Pattern Electroretinogram (PERG) as an indicator of early Hydroxychloroquine toxicity
AU	Sharp DM
AU	Sissingh JI
AU	Lunt B 
IN	Eye Department, Auckland Hospital, Auckland, New Zealand. 
AD	Private Bag 92024, Auckland 1001, New Zealand. 
EM	akvision@ahsl.co.nz 
AB	Purpose: While Chloroquine toxicity has been well recognized, Hydroxychloroquine toxicity and the potential for progression after cessation of treatment has been poorly documented. This study aimed to identify early signs of Hydroxychloroquine toxicity using a practical monitoring protocol.    Methods:  Based on reported retinopathy in the international literature, a Hydroxychloroquine monitoring protocol was established. Baseline tests included visual acuity, Ishihara colour vision, Humphrey 10-2 central visual field and dilated fundus examination. The recommended dosage was 6.5mg/kg with a cumulative dose < 700g. A PERG was performed on patients with abnormalities noted on the visual field test or fundus examination and on patients who had exceeded the recommended dosage.  Results: Decreased visual acuity, Ishihara colour vision defects and clinically obvious fundus changes occurred as a late stage of toxicity.  The computerised visual field testing of the central 10 degrees identified reduced paramacular sensitivity with ring scotomas 3 to 8 degrees from fixation as the classic defect in Hydroxychloroquine toxicity.  Subtle visual field defects were often more difficult to interpret. The PERG was able to identify abnormal macular function at an early stage of toxicity and to differentiate potential toxicity from localised retinal pigment epithelial abnormalities. A patient with significant progression of toxicity over a three-year follow-up highlighted the urgency for early recognition.  Conclusions: Case studies suggest the PERG provides an early indicator of macular dysfunction in Hydroxychloroquine therapy. In combination with computerised central visual field testing it is a valuable tool for early detection of a potentially progressive toxic maculopathy.

TI	L and M cone signal contributions to the multifocal ERG: interdividual and topographical variation
AU	Sharpe LT
AU	Albrecht JF
AU	Jägle H
IN	Forschungsstelle für Experimentelle Ophthalmologie, Universitäts-Augenklinik
AD	Röntgenweg 11, D-72076 Tübingen, Germany
EM	ted.sharpe@uni-tuebingen.de
AB	Purpose  To estimate interindividual and topographical variation in the distribution of long-wave (L-) and middle-wave (M-) sensitive cones in normal observers, using the multifocal ERG. Methods Subjects were 15 males and 4 females.  Their multifocal ERGs were measured with a DTL fiber electrode; the responses of which were amplified and filtered between 10 and 100 Hz (Grass Instruments).  The Stockman & Sharpe (1999) cone fundamentals were used, in combination with “silent substitution” techniques, to generate L- and M-cone-isolating stimuli, which had a maximum Michelson contrast of 46%. The stimuli were generated on a flat-screen SONY Trinitron CRT monitor, using a 37-element array of hexagonal cells (VERIS system Version 3.1) which subtended 58° x 50° of visual angle at a viewing distance of 32 cm.  The recorded signals were analyzed according to retinal quadrant (nasal, temporal, superior, inferior), whole rings, and half-rings oriented along the horizontal meridian at 0° (+2.5°), 6° (+3.5°), 14° (+4.5°), and 23.75° (+5.25°) of retinal eccentricity.  L-cone to M-cone ratios were estimated at the various retinal locations by model fits and compared with psychophysical estimates obtained from heterochromatic flicker photometry for centrally and peripherally fixated 2° fields.  Results  For the whole field stimulus, the L/M cone ratio ranged from approximately 0.88±0.085 to 2.5±0.19 with a mean of 1.7.  An extreme (inverted) value was found in a female carrier for protanopia, whose L/M cone ratio was 0.12±0.03. The foveally and peripherally determined L/M cone ratio values correlated highly with those determined from heterochromatic flicker photometry.  No consistent differences in L/M cone ratio were found between the two eyes of any observer nor between the superior and inferior retinal hemifields in each eye.  However,  the L/M cone ratio was approximately 35%±22% times greater in the nasal than in the temporal retinal half-fields.  In general, the ratio increased with eccentricity from the fovea. The maximum variation in the L/M cone ratio with retinal eccentricity, in a normal male observer, was 1.3 (fovea) to 3.1 (23.75° nasally); the minimal variation was 0.82 (fovea) to 1.0 (23.75° nasally) in a female observer. Conclusions The topography of  the L- and M-cone signals can be measured in color normal observers by the multifocal ERG.  The derived L/M cone ratios correlate with those obtained from psychophysical estimates and are similar to those derived from L- to M-cone pigment mRNA ratios in human and Old World monkey populations.

TI	Primary open angle glaucoma: a study using multi-tests approach of electrophysiology, ultrasonography and fluorescein angiography. 
AU	Shihab AA. 
IN	Minia University, School of Medicine, Ophthalmology Dept., Mini, Egypt. 
AD	PO Box 246 Roman, Giza, Egypt. 
EM	dshihab@hotmail.com 
AB	Purpose: The aim of the present work is to study cases with primary open angle glaucoma (POAG) depending mainly on objective tools instead of common subjective ones. Electrophysiology, ultrasonography and flourescein angiography (FA) were chosen. Methods: Twenty normal subjects (40 eyes) and twenty patients (38 eyes) of a similar age group were studied. All were attendants of Minia University outpatient clinic. Patients and normal subjects had a full ophthalmic examination and underwent ultrasonography and electrophysiology testing. FA was performed only on the patients. The hypothesis of retinal ischemia as an underlying mechanism of visual loss in POAG  was studied. Critical fusion frequency was detected using the Full Field Flicker ERG. FA was performed to detect optic nerve head ischemia. The extent of nerve fiber death or atrophy was assessed as a decrease in the echographic optic nerve diameter. The obtained data were statistically analyzed using t-test. Results: Retinal ischemia monitor results were highly significant in differentiating glaucoma patients from normals (p <0.000). The critical fusion frequency for patients was much lower than for normals and the difference was highly significant (p<0.0002). The echographic measurement of optic nerve diameter in POAG subjects was significantly smaller than in normal subjects (p<0.001). Peripapillary optic atrophy and absolute filling defect were constant findings among the examined group of patients. Conclusion  : A multi-test approach using objective tests is very useful and reliable in establishing the diagnosis of POAG and in pointing out the underlying pathology. It is useful in early detecting glaucomatous damage especially in difficult cases with opaque media or optic disc anomalies.

TI	Amplitude-check size function of pattern reversal visual evoked response in patients with macular diseases. 
AU	Shihab AA 
IN	International Eye Hospital, Cairo, Egypt. 
AD	POBox: 246 Orman , Giza, Egypt. 
EM	dshihab@hotmail.com 
AB	 Purpose: The aim of the present work is to interpret PVER in an unconventional way so as to examine its efficacy in detecting macular lesions and early macular problems. Methods: 20 normal subjects (35 eyes) and 15 patients (21eyes) were included in the study. The patients were from the International Eye Hospital. The normal subjects were volunteers from hospital staff and were matched in age to the patient group. All had complete ophthalmic examinations. Only patients had fundus photography on both eyes. All had PVER test. The steady-state PVER was recorded with five check sizes (36.6, 73.2, 90.9, 120, 150 minutes of arc). The amplitude-check size function was plotted for each patient. The maximum and minimum PVER amplitudes were calculated. The area under the function was calculated (spatial tuning area). Results: Values for the patients with macular lesions were significantly smaller than those for normal subjects and the shape of the function was distorted. Conclusion: The two dimensional analyses of PVER provided a tremendous amount of information about the visual system. It proved useful in diagnosing patients with macular lesions and in separating normal subjects and patients with early macular lesions.

TI	Human Retinal Color processing steps revealed by Phase and Amplitude ERG Response to sinusoidal stimuli.
AU	Siebert F.
AU	Gemperlein R.
IN	Zoologisches Institut, Ludwig-Maximilians-Universität, 
AD	Luisenstrasse 14, D-80333 München
EM	rg@zi.biologie.uni-muenchen.de
AB	Purpose: Human ERG is recorded under photopic conditions using coloured sinusiodal Ganzfeld stimuli. By analyzing the amplitude and phase response and by the comparison of the responses to different color stimuli the characteristics of the underlying processes can be revealed. Methods: Output of a xenon lightsource is sinusiodally intensity modulated (2-30Hz) by a mechanical scanner. In addition different color filters (red, green, violett and white (no filter) in appearence) are applied. Each result is combined from 4 single measurements (2-3, 4-7, 8-16, 17-31Hz) to avoid nonlinear interference effects. The ERG response to Ganzfeld conditions (Ulbricht sphere) is recorded using an eyecup electrode (Nicolet). After applying the FFT the linear amplitude and phase spectra of the 4 measure-ments for each color stimuli where combined to full range response. Results: Amplitude responses to white, green and violet show a dominant peak at 2-3Hz and the maximum of white light response is reduced to approximately 50% of the colored responses. All curves but the response to red show a shoulder from 4Hz to 8Hz, which only for violet extends up to 15Hz. Red response shows nearly no distinct shoulder at all. Unexpectedly all responses are constant on different levels from 15Hz to 30Hz. The overall shapes of white and green response are very similar. Each of the phase response to white, green and violet stimuli is nearly linear decreasing for increasing frequences, but showing a different offset which remains constant over all measured frequences. Only the red response shows a divided shape: for 2-12Hz it is linear with maximum offset of all measurements, but for 16-30Hz it is nearly similar to the white phase curve. The offset for green phase response in comparison to white response is about 50 degree, for violettresponse about 90 degrees, for red response about 130 degrees (2-12Hz) and about 20 degrees (15_30Hz).
Conclusion: The parallel shifted phase charachteristics of green, violet compared to white seems to reflect processing of color stimuli, because differences in temporal processing would cause divergent phases for higher frequencies. So the amplitude spectrum is obviously not only generated by the receptors, but also from related color opponent systems. The measured response is the result of the superimposing output of several generators that are summed up by vector addition. Further studies will deal with this addition to explain e.g. the amplitude spectra and the striking shape of red phase spectrum.

TI	Oscillatory Potentials of the Electroretinogram in the follow-up of hypertensive patients with four different pharmacological treatments. 
AU	Solimano N
AU	Rinaldi G
AU	Ravalico G
IN	University Eye Clinic of Trieste
AB	Purpose: Oscillatory potentials of the electroretinogram are useful to confirm the diagnosis of essential hypertension.The oscillatory index can be considered an early marker of retinal vasculature damage.our purpose is to find any differences in the oscillatore potentials among the groups of hypertensive patients with four different pharmacological treatments.  Methods: Forty-six hypertensíve patients underwent primary antihypertensive therapy with four different pharmacological treatments: angiotensin-converting enzyme inhibitors (12 subjects); angiotensin AT1 receptor antagonists (11 subjects); betablockers (12 subjects); calcium antagonists (11 subjects). Oscillatory potentials were recorded before the treatment and after twenty-four months with Lace Erev 2000 (ISCEV Standards).  Results:The oscillatory index increased in a statistically significant manner in the angiotensin-converting enzyme inhibitor group and in the calcium antagonist group.Conclusion: Probably angiotensin-converting enzyme inhibitors and calcium antagonists increase the retinal blood flow with a mechanism of vasodilatation.

TI	Spatial and temporal profile of visual evoked magnetic field (VEF) to pattern-reversal stimulation
AU	Tanikawa H
AU	Ohde H
AU	Kurobe Y
AU	Haruta Y
AU	Mashima Y
AU	Oguchi Y
IN	Keio University
AD	35 Shinanomachi, shinjuku-ku, Tokyo 160-8582, Japan
EM	czb03025@alles.or.jp
AB	Purpose: Magnetoencepharography (MEG) is one of the non-invasive methods developed for studying human-brain function and has been applied to many studies of human visual function. In this report, we used MEG to study spatial and temporal profile of the VEF following the pattern reversal stimulus. Methods: The VEF of three normal adults were recorded in a magnetically shielded room using a 150-channel whole-head type gradiometer. The visual stimulation of sinusoidal grading pattern reversal were carried out with temporal frequencies from 4Hz to 16Hz and spatial frequencies from 1cycle/degree (c/d) to 10c/d. This stimulus were presented in front of the subject. The sources of the VEF components were estimated using the equivalent current-dipole (ECD) estimation method. To analyze the VEF components, the data were classified by Fast Fourier Transform (FFT) analysis, and the power of the fundamental frequency component and the second harmonic component were measured. Results: The VEF changed alternately at the right and left hemisphere of the posterior region with the same frequency as the stimulus rate. The two ECDs were estimated at the primary visual cortex, and the directions of these two ECDs were symmetrical. The power of the fundamental frequency component was maximal when the stimulus temporal frequency was 8Hz and spatial frequency was 1c/d. The power of the second harmonic was maximal when the stimulus temporal frequency was 8Hz and the spatial frequency was 6c/d. The VEF became very small when the temporal frequency was over 16Hz. There was a modulation transfer function-like profile of the spatial frequency at the second harmonic, otherwise the fundamental frequency was not. Conclusions: The second harmonic component should depend on the pattern stimulus. It was interesting that the two ECDs appeared at right and left visual cortex alternately with the sinusoidal grading pattern reversal stimulation, otherwise the two ECDs were estimated simultaneously at both visual cortexes with the transient stimulation.

TI	Cone electroretinograms recorded under the clinical slit-lamp examination
AU	Tanikawa A
AU	Kondo M
AU	Suzuki M
AU	Miyake Y
IN	Department of Ophthalmology, Nagoya University, School of Medicine
EM	tani@med.nagoya-u.ac.jp
AB	Purpose:  To determine the clinical usefulness of a new contact lens electrode, which is attached to the Goldmann applanation tonometer, for recording full-field cone electroretinograms (ERGs).  Methods:  A high-brightness, white light-emitting diode (LED) (peak, 440 and 540 nm) was incorporated into a contact lens electrode which was   attached to the Goldmann applanation tonometer of the slit-lamp.  The white LED served as the source for both stimulus and background.  A white diffuser was placed between the LEDs and cornea to produce a homogeneous stimulus and background illumination to the retina.  Full-field photopic ERGs and 30 Hz flicker ERGs were recorded with stimulus intensity of 9200 (photopic ERG) and 1100 (flicker ERG) cd/m2 on a steady background of 41 cd/m2 from five normal subjects (age, 18 to 62 years) and a patient with cone dystrophy.  Results:  We successfully recorded reliable photopic ERGs and 30 Hz flicker ERGs from normals and a patient with cone dystrophy.  Mean (+- SD) amplitudes of photopic ERG (b-wave) and flicker ERG for normals were 106.7 (+- 41.3) and 85.6 (+-18.2) uV, respectively.  Mean (+- SD) implicit times of photopic ERG (b-wave) and flicker ERG for normals were 30.9 (+-1.7) and 37.7 (+- 3.2) msec, respectively. In a patient with cone dystrophy, severely reduced responses were recorded.  Conclusions: Our system made it possible to record photopic and 30 Hz flicker ERGs immediately after the clinical slit-lamp examination.  The compactness and ease of using this system suggest that it will be clinically useful for the screening of retinal disorders.

TI	Functional and Electrophysiological Correlates of Visual Loss With Vigabatrin (Sabril)
AU	van der Torren, K
AU	H. Graniewski, H
AU	Polak BCP
IN	Ophthalmology Dept, Merwerdeziekenhuis Dordrecht,
AD	Twintighoevenweg 17, 3312 LS Dordrecht, The Netherlands.
AB	Vigabatrin (Sabril) is an anti-epileptic agent which has been used for about 10 years as ana djunct treatment for patients with epilepsy and the West syndrome when there are difficulties in regulating the treatment. At the end of 1997 the first announcements were made in the neurological literature about vigabatrin-associated visual field constriction. It seems now after ERG and visual field examination, that there is serious vision field constriction and related  vision function loss on the ERG examination.

TI	The Fast Spiking STR: A photophobic oculomotor artifact occurring near absolute scotopic threshold.
AU	Vaegan
AD	VisionTest Australia, The Eye and Vision Resarch Institute, 187 Macquarie St, Sydney, 2000 Australia .
EM	vaegan@unsw.edu.au
AB	Aim: To explain the generator for a peculiar, rare form of scotopic threshold response STR. Background: The STR is an apparently simple, small (<15uV), broad (ca 30msec wide) negative going  ERG wave with a peak time of about 85-140 msec depending on intensity. It can be recorded with increasing amplitude for about 3 Log Units above absolute threshold. This STR is now known to have at least two components of about equal size, one of which is generated by ganglion cells. For 8 years I have occasionally observed, mainly in patients with early or late onset slowly progressive cone dystrophies, an STR with a very fast swtiching PNPNP shape, which increased in amplitude with intensity. A similar pattern has never been seen in any animal study. Methods: An STR amplitude intensity series was routinely recorded in all ERG patients for 9 years. Initial studies, for 4.5 years in a hospital clinic, used gold foil electrodes. In the second 4.5 years DTL electrodes were used in over 600 suceessive patients. Results: The fast switching pattern was seen in about 20 patients in the first series, including a father and daughter. In the latter series it was seen about 8 times. The fast switching form was less complex with DTL electrodes and the shape was sometimes just NP. One patient in the latter series had early RP. In 2 others the response continued to grow right up to the maximum intensity flash and could be seen in the ongoing record to be an eye movement artifact.. Conclusion: The fast switching STR is more complex and frequent with electrodes which contact the cornea. It is mainly unusual because it is generated near threshold. It is probably an artifact of habitual photophobia and due to a heavily damped oculomotor response, either from eye movements, lid tightening, or the retractor bulbi. It is not a new type of evoked response or a useful clinical sign.

TI	The Appearance of Multifocal ERG in Primary and Secondary Maculopathies
AU	Wu L-Z
AU	Huang SZ
AU	Wu D-Z
AU	Ma JM
IN	Zhongshan Ophthalmic Center, Sun Yat-Sen Univesity of Medical Sciences,
Guangzhou, China
AD	54 Xianlie Nan Road, Guangzhou 510060, China
EM	lwuicv@gzsums.edu.cn
AB	Purpose:  To observe and compare the differences of multifocal ERG (MF-ERG) in primary and secondary maculopathies. Methods:  Testing with VERIS Science Tm 4.0 System, the MF-ERGs from 11 eyes of age-related macular degeneration, 7 eyes of idiopathic macular hole, 6 eyes of diabetic retinopathy and 2 eyes of central retinal vein occlusion were analyzed and compared.  Results:  Comparing with primary maculopathies as dry form age-related macular degeneration and idiopathic macular hole, the MF-ERGs of secondary maculopathies had wider and more irregular changes in the peripheral responses.  The longer latencies and abnormal average response densities of MF-ERGs were related to the retinal lesion field and conditions of system or original diseases. Conclusion:  The different appearances of MF-ERG between primary and secondary maculopathies will help to evaluate the visual function and prognosis in macular diseases.

TI	The visual function of idiopathic macular hole before and after surgery
AU	Wu D-Z
AU	Zhao T 
AU	Gao R 
AU	Zhang S. 
AU	Wu L 
AU	Liang J 
IN	Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Sciences 
AD	54 Xianlie Nan Road, 510060 Guangzhou, China
EM	wdzzoc@gzsums.edu.cn
AB	Purpose: To investigate visual function in idiopathic macular hole (IMH) before and after macular surgery. Methods: Vitreous-retinal surgery was performed in 19 patients (19 eyes) with IMH. Among them, 3 eyes were stage 2, 10 eyes were stage 3, 6 eyes were stage 4. Visual functions including visual acuity, laser retinal visual acuity, photopic ERG intensity responses and Humphrey 30o-2 visual field were tested and compared before and after surgery. The mean time of follow-up was 4 months. Results:  visual acuity: best-corrected visual acuity was from 0.01 to 0.1 before operation, and from 0.04 to 0.4 after operation, there was no statistically significant difference between pre- and post-operation (p>0.05).  laser retinal visual acuity: this was from 0.12 to 0.4 before operation, and from 0.2 to 0.63 after operation, there was statistically significant difference between pre- and post-operation (p<0.05).   photopic ERG intensity responses: in the region from 0.5log units to 3 log units of stimulus intensity, the intensity-response of b-wave shown the S-shaped curve, which fits the Naka-Rushton curve. The value for Log K was decreased after surgery, there was statistically significant difference between pre- and post-operation (p<0.05). There was no statistically significant difference between pre- and post-operation for Rmax and n.  visual field: the thresholds for 0-10o area increased after surgery, there was statistically significant difference between pre- and post-operation (p<0.05), but there was no statistically significant difference between pre- and post-operation for 15-30o area. Conclusions: The visual function of cones in the macular region is increased by macular surgery for IMH.

TI	Visual Electrophysiology for Alcoholic Ocular Changes
AU	Yin Weijing
AU	Guo Xirang
AU	Dong Yingli
AU	Wang Mei
AD	Henan Institute of Ophthalmology, Zhengzhou, 450003, CHINA
AB	Objective: We observed and followed-up the ocular damage of  acute or chronic alcoholics with visual electrophysiologic detection and studied its pathologic mechanism. Method:  Scotopic  ERG,  flash- or pattern-VEP (F-VEP or P-VEP) and visual field, fluorescein angiography with fundus photography (FFA)  were performed for 9 cases  (18 eyes) with  alcoholic ocular changes. Maximal combined response of ERG and P-VEP  were detected according to international  standard  protocols. Pattern  VEP stimulation was with 32 minute of arc checks, with contrast of 80%. Amplitudes of a-  b-ERG  wave and  the implicit times of  VEP  p100 component were analysed. Results: 2 of 3 cases (4 of 6 eyes) presented normal ERG response and irrecorded F- or P-VEP P100  component in acute alcoholics. They returned to normal after treatment. One case ( 2 eyes) showed  permanent ERG a-   b- wave  amplitude and  P- VEP   P100 components changes. Irreversible visual field abnormalities of a-, b-wave amplitudes and P100 latency were found in chronic alcoholics. Extensive  retinal  pigment  layer  damage  was  demonstrated  by  FFA examination in  acute  and  chronic  alcoholics. Conclusion  Acute  or chronic alcoholism can damage retinal pigment epithelium and the ERG and VEP can  monitor these ocular changes.

TI	Multifocal electroretinogram is distorted by Artifact Removal procedure
AU	Yoshii, M
AU	Yanashima, S
AU	Suzuki, S
AU	Okisaka, S
IN	Department of Ophthalmology, National Defense Medical College
AD	Namiki 3-2, Tokorozawa-shi, Saitama-ken, 359-8513 Japan
EM	masaruy@mb.infoweb.ne.jp
Purpose: To study whether the ‘Artifact Removal’ procedure that is thought to remove artifacts effectively in the multifocal electroretinogram system (mERG) works correctly or not.  Methods: A test wave was made only in the center part of the stimulus elements using a photo-diode circuit. mERGs were recorded using the Veris III system (Mayo corporation) from a well-trained normal subject, and were analyzed by the Artifact Removal procedure that is included in the Veris Science software program. The stimuli consisted of densely arranged arrays of 103 or 37 hexagonal elements. The pupils were fully dilated and a bipolar contact lens electrode was used. It took 8 minutes to obtain one mERG record, and 16 segments were required to perform this record. The second order kernel response components were extracted by Veris Science software, and the artifact removal procedure was done for both first and second order kernel response components. Results: Artifact Removal procedure influenced both the test wave on the center element as well as the ‘immediate neighbor’ traces. After repeating the Artifact removal procedure, the shape of the test wave changed considerably. Some of the traces of the second order kernel response components elicited from a normal subjects changed irregularly when the Artifact Removal procedure was repeatedly used. Conclusions: mERG is distorted by the Artifact Removal procedure.

TI	Multifocal critical flicker fusion frequency in diagnosis of visual field defects
AU	Zueva MV 
AU	Tsapenko IV
AU	Golubtsov KV 
AU	Zakharova GJu
AU	Khashaev ZKh-M
IN	Moscow Helmholtz Research Institute of Eye Diseases
AD	Moscow, Russia, Sadovaja-Chernogrjasskaja 14/19
AB	Introduction: Methods for examination  of visual field defects include different modifications of computer  perimetry and estimation of critical flicker fusion frequency (CFFF). In  this paper, the new method of  diagnosis of visual field defects -  multifocal CFFF - is presented, which may have the advantage of being more specific for particular types of defects. Methods: The method is based on the use of a new diagnostic device which  includes a light-tight mask with eye-glasses-stimulator in the form of  two hemispheres. Inside the each of eye-glasse hemispheres, 39 (or more)  multi-colour (red, blue or green) light-emitting-diods (LEDs) are inserted  centrally and in several paracentral and peripheral rings. The  examination of CFFF is carried out at all the points successively using a different intensity and colour of stimulation. The data are registered in multifocal maps by means of a computer program.  Results: The multifocal mapping of CFFF was performed in 8 healthy subjects  and in patients: with flat rhegmatogenous retinal detachment (RD) in the  upper part of fundus, disciform stage of age-related macular dedeneration  (AMD) and with a tumor in the  left visual cortex. In the  maps of CFFF in healthy subjects, the non-homogeneous distribution of  sensitivity to flicker was shown for different local zones of  the visual fields. All the patients were also tested with a Rodenstock Perimat field  Analyzer.  We have observed similar results of field loss (altitudinal  hemianopsia) from both methods in the patient with RD. The correlation  between the data of multifocal CFFF and the threshold visual field was  subjectively judged to be good in this case. However, in the  patient with a tumor in the left brain hemisphere, the right side homonymous  hemianopsia was shown in threshold perimetry  and a left side loss of  flickering sensitivity was revealed with multifocal CFFF. The  patient with AMD had a central scotoma in the visual field but showed a general decrease of CFFF in multifocal mapping.  Conclusion: The data of multifocal CFFF and threshold visual field may  differ in different visual system pathologies. The  method of CFFF mapping is a new, independent  test to measure the fine  defects in visual field and has potential for clinical use.