Cone function in children with a history of preterm birth

Color vision was examined by psychophysical tests and photopic color full-field electroretinography (ERG) in formerly preterm children, and compared with those of full-term children. In a prospective case–control study, 25 patients with a history of preterm birth 7–14 years of age were divided into three groups: group I, laser-treated retinopathy of prematurity [ROP] (n = 7); group II, spontaneously regressed ROP (n = 8); group III, no ROP (n = 10). Age-matched full-term born children comprised the control group (n = 8). Color vision was assessed by Fansworth D15 and Lanthony desaturated D15 tests. The cone function was tested using photopic full-field ERG. Besides the ISCEV standard stimuli, blue light on amber background was also used (S-cone ERG). The correlation between ERG parameters and prematurity or ROP was determined. We found no significant differences between any patient group and the control group in the results of the psychophysical tests, and implicit times of the ERG responses. The ERG b-wave amplitudes were significantly lower in group I (laser-treated ROP) compared to controls, for 2 of 4 stimulus conditions i.e. the standard (P = 0.028) and S-cone (P = 0.017) single flash ERGs. The general estimating equation model statistics found a significant effect of prematurity on the b-wave amplitudes (P = 0.025, standard, P = 0.014, S-cone ERG). A slightly reduced photopic ERG b-wave amplitude may be associated with prematurity.     

Differential changes in retina function with normal aging in humans

We evaluated the full field electroretinogram (ERG) to assess age-related changes in retina function in humans. ERG recordings were performed on healthy subjects with normal fundus appearance, lack of cataract and 20/20 acuity, aged 20–39 years (n = 27; mean age 25 ± 5, standard deviation), 40–59 years (n = 20; mean 53 ± 5), and 60–82 years (n = 18; mean 69 ± 5). Multiple ERG tests were applied, including light and dark-adapted stimulus-response function, dark adaptation and dynamic of recovery from a single bright flash under dark-adapted conditions. Changes in ERG properties were found in the oldest age group when compared with the two younger age groups. (1) The photopic hill effect was less pronounced. (2) Both photopic a-wave and b-wave amplitudes and implicit times were increased at high stimulus strengths. (3) Dark adaptation time was delayed for pure rod and L/M cone-driven responses, respectively. (4) Dark-adapted a-wave but not b-wave amplitudes were reduced, yielding higher B/A ratios. (5) Dark-adapted a- and b-waves implicit times were prolonged: there was a direct proportional correlation between minimal a-wave implicit times and age. (6) The dynamic of dark current recovery from a bright flash, under dark-adapted conditions, was transiently faster at intervals between 0.9 and 2 s. These results denote that aging of the healthy retina is accompanied by specific functional changes, which must be taken into account to optimally diagnose potential pathologies.     

Helicoidal peripapillary chorioretinal degeneration: electrophysiology and psychophysics in 17 patients

AIMS—To characterise retinal function using electrophysiological and psychophysical tests in 17 patients with helicoidal peripapillary chorioretinal degeneration.
METHODS—The electroretinogram (ERG) was recorded using gold foil corneal electrodes. The electro-oculogram (EOG) was recorded using a standard protocol. Dark adaptometry was recorded with an SST-1 dark adaptometer and colour vision assessed with Ishihara plates and Farnsworth D-15.
RESULTS—All subjects had a recordable ERG. The amplitudes and implicit times of the a- and b-waves were within normal limits at all luminances in five subjects (age 21-70 years, mean 40 years). The ERG of six (age 26-55 years, mean 40.7 years) had subnormal amplitudes at all luminances, but normal implicit times, and six (age 38-81 years, mean 60.7 years) had abnormal ERGs with marked reduction of a- and b-waves, and delayed implicit times of the b-wave. The implicit times of the a-wave were normal in all subjects. A reduction in the b/a wave ratios was not found, nor was there selective loss of scotopic, mixed rod/cone, or cone responses. The light/dark ratio of the EOG was subnormal (150-185%) or abnormal (below 150%) in all but three subjects. Two patients with normal EOG showed normal ERGs in both eyes, but one had subnormal ERGs in both eyes. The scotopic sensitivity was normal in all subjects and dark adaptation showed a normal time course. Colour vision was normal in all patients.
CONCLUSION—The results suggest that in most cases the function of the retinal pigment epithelium is affected by this disease before any changes in the function of the sensory retina are detectable by our methods, and that retinal dysfunction is focal rather than diffuse.

Keywords: chorioretinal degeneration; electroretinogram; dark adaptation; colour vision     

Adaptational changes in cone electroretinograms in man

Changes of amplitude and implicit time of human cone electroretinogram (ERG) were studied during dark adaptation and succeeding light adaptation. Dark-adapted cone ERG was isolated by subtracting scotopic blue response from matched scotopic red response. The former represented the rod-mediated b-wave, while the latter consisted of both rod-mediated b-wave and cone-mediated b-wave or x-wave. The b-wave amplitude of dark-adapted cone ERG remained unchanged during dark adaptation, while the implicit time increased systematically, reaching a plateau. Light-adapted cone ERG was obtained by red stimulus lights under a bright background light. The amplitude of light-adapted cone ERG was markedly suppressed through dark adaptation but it recovered gradually during light adaptation, reaching the base line level. The implicit time was unchanged during light adaptation.     

Consecutive unilateral recording of the two eyes affects dark-adapted ERG responses,when compared to simultaneous bilateral recording

Purpose

Our aim was to compare the electroretinographic (ERG) responses of two eyes obtained by consecutive unilateral recordings to those obtained by a simultaneous bilateral recording in sheep.

Methods

Eight sheep underwent two full-field ERG recordings, using two recording strategies of the standard ISCEV protocol: consecutive unilateral recordings of one eye after the other, and simultaneous bilateral recording of both eyes. The order of recording strategy within an animal (unilateral/bilateral), eye recording sequence in the unilateral session (OD/OS), and amplifier channel assignment for each eye were all randomized. To test whether duration of dark adaptation and/or anesthesia affect the results, the ISCEV protocol was recorded bilaterally in six additional eyes following 38 min of patched dark adaptation, as was done for the second eye recorded in the consecutive unilateral recordings.

Results

The second recorded eye in the unilateral session had significantly higher scotopic b-wave amplitudes compared to the first recorded eye and to the bilaterally recorded eyes. A-wave amplitudes of the dark-adapted mixed rod–cone responses to a high-intensity flash were also significantly higher in the second eye compared to the first eye recorded unilaterally and to the bilaterally recorded eyes. Light-adapted responses were unaffected by the recording strategy. When the ISCEV protocol was recorded after 38 min of dark adaptation, the scotopic responses were higher than in the first eyes, and similar to those of the second eyes recorded unilaterally, suggesting that indeed the longer duration of anesthesia and dark adaptation are responsible for the increased scotopic responses of the second eye.

Conclusions

Consecutive unilateral ERG recordings of two eyes result in higher amplitudes of the dark-adapted responses of the eye recorded second, compared to the eye recorded first and to bilaterally recorded eyes. The differences in scotopic responses can be attributed to different duration of dark adaptation and/or anesthesia of the two consecutively recorded eyes. Photopic responses are not affected. Therefore, simultaneous bilateral ERG responses should be recorded when possible, especially for evaluation of scotopic responses.

     

Association of electroretinogram and morphological findings in branch retinal vein occlusion with macular edema

The objective of this study is to evaluate the relations among electroretinogram parameters (cone a-wave, cone b-wave, and 30-Hz flicker), retinal thickness, and retinal volume in patients with branch retinal vein occlusion (BRVO) and macular edema. We prospectively examined 33 patients (33 eyes) with BRVO and macular edema. The amplitude and implicit time of the a-wave cone, b-wave cone, and 30-Hz flicker were calculated automatically from the ERG. Retinal thickness and volume were measured by optical coherence tomography (OCT) in nine macular subfields. Then, correlations between the ERG parameters and morphological parameters were analyzed. The 30-Hz flicker amplitude was significantly smaller in the eyes with BRVO and macular edema than in the unaffected contralateral eyes. Thirty-hertz flicker and cone b-wave implicit times were significantly longer in the eyes with macular edema than in the unaffected eyes. The implicit time of the cone b-wave was correlated with both retinal thickness and retinal volume in the temporal subfields. Thirty-hertz flicker amplitude was correlated with both retinal thickness and volume in the temporal and superior outer (site of occlusion) subfields, while 30-Hz flicker implicit time was correlated with retinal thickness and volume in the outer temporal subfield. Multiple regression analysis demonstrated that the retinal thickness and volume of the temporal subfields were significant “determinants” of the implicit time for the cone b-wave and 30-Hz flicker, as well as the 30-Hz flicker amplitude. These findings suggest that OCT parameters of the temporal region may reflect postreceptoral cone pathway function in BRVO patients with macular edema.     

Cone electroretinogram amplitude growth with light adaptation in patients with retinitis pigmentosa

PURPOSE: It has been hypothesized that the increase in the b-wave during light adaptation is directly related to the level of cone malfunction in patients with retinitis pigmentosa (RP). Because this hypothesis has important bearing on the mechanism for the increase in the electroretinogram (ERG), we examined the increase in the amplitude of the cone ERG during light adaptation in patients with typical RP. METHODS: Cone ERGs were recorded to Ganzfeld white flash stimuli in the presence of white background illumination in 51 RP patients and in 27 normal subjects. RESULTS: In the normals, the increase in the b-wave amplitude during light adaptation ranged from 14-92% of the dark-adapted amplitude. All RP patients showed an amplitude increase that ranged from 5 to 100% of the baseline amplitude. This increase was not significantly different from that of the normals (p = 0.71, unpaired t-test). The baseline amplitudes and the increase in the relative amplitude were weakly correlated in the RP patients (r = 0.31; p = 0.029). No significant difference was observed in the amplitude increase between patients with near normal b-wave implicit times and those with delayed times (p = 0.17, unpaired t-test). Changes of the b-wave implicit time were not significantly different from those in the controls. CONCLUSION: These findings that the changes in the cone ERG with light adaptation in the RP patients were very similar to those in normal subjects do not support the proposed hypothesis that the increase in the b-wave amplitude during light adaptation was directly related to the level of cone malfunction.     

Comparison of electroretinographic responses between two different age groups of adult Dark Agouti rats

AIM: To describe and compare the differences in electroretinographic responses between two different age groups of adult Dark Agouti (DA) rats and to better understand the effect of age on retinal histology and function.METHODS: The electroretinographic responses of two different age groups of adult DA rats were compared. Animals were divided into younger adult DA rats 10-12wk (n=8) and older adult DA rats 17-19wk (n=8). Full field electroretinography (ERG) was recorded simultaneously from both eyes after dark adaption and light adaption and parameters including the positive scotopic threshold response (pSTR), negative scotopic threshold response (nSTR), scotopic a-wave, b-wave, photopic a-wave, b-wave and photopic negative response (PhNR) were compared between groups.RESULTS: The older adult rats displayed lower stimulation thresholds of the STRs (pSTR and nSTR) and higher amplitudes of pSTR, scotopic a-wave and b-wave, photopic b-wave and PhNR amplitudes, with shorter implicit times. Photopic a-wave amplitudes were however higher in the younger adult rats.CONCLUSION:In summary, for the rod system, photoreceptor, bipolar cell and RGC activity was enhanced in the older adult rats. For the cone system, RGC and bipolar cell activity was enhanced, while photoreceptor activity was depressed in the older adult rats. Such age-related selective modification of retinal cell function needs to be considered when conducting ophthalmic research in adult rats.     

Cone and rod dysfunction in fundus albipunctatus with RDH5 mutation: an electrophysiological study

PURPOSE: A prior study showed that some patients with fundus albipunctatus (FA) have severely reduced full-field cone ERGs. The purpose of this study was to investigate the frequency of cone dysfunction and to determine the cause of the reduced full-field cone ERGs in patients with FA and whether the rod system is affected in patients with FA. METHODS: Sixteen consecutive patients with FA (from 1993 to 2003; eight males, eight females; mean age, 25.4 years) with an RDH5 gene mutation were studied. The amplitudes and implicit times of the standard cone ERGs in the patients with FA were compared to those obtained from normal subjects (n = 55). The a-waves of cone ERGs were also elicited by a bright flash and were fitted to a mathematical model of the a-wave. Rod ERG responses were elicited by dim blue flashes after 3 hours of dark adaptation. RESULTS: The amplitude of the b-wave of the cone ERG in the FA group varied considerably from within the normal limits to markedly decreased. Six of 16 patients with FA had b-wave amplitudes that were smaller than the lowest limit of the control subjects. The degree of cone dysfunction tended to be more severe in older patients. The analysis of the cone a-wave demonstrated that R(m) (maximal response amplitude) in the patients with FA with reduced standard cone ERGs was significantly smaller than that in control subjects. Rod ERGs were also reduced in the patients with FA who had reduced cone ERGs. CONCLUSIONS: In patients with FA, 38% had extensive cone dysfunction. The reduced full-field cone ERGs were mainly due to the loss of cone photoreceptors, and the rod system was also affected in some patients.     

Development of ERG responses: The ISCEV rod, maximal and cone responses in normal subjects

PURPOSE: Summarize ISCEV ERG responses from normal infants and children. METHODS: The amplitudes and implicit times of the ISCEV rod, maximal dark-adapted and cone responses from a total of 409 normal infants (n = 128), children and adult controls were compiled. The subjects, aged 1 week to 52 years, were divided into seven age groups, including four in infancy (< 52 weeks). The response parameters for each age group were summarized as percentiles. RESULTS: In each ISCEV condition, the youngest infants (1-5 weeks) had significantly smaller amplitudes and longer implicit times than adults. Amplitude increased and implicit time decreased systematically with age. CONCLUSIONS: The developmental changes in ERG responses are significant. The medians and ranges herein provide provisional norms against which the ERG responses from pediatric patients can be compared.     

干性年龄相关性黄斑变性的局部视网膜电流图研究

目的研究干性年龄相关性黄斑变性(Age—related macular degeneration AMD)患者的局部视网膜电流图(LERG)反应，探讨黄斑区视网膜功能损害的程度。方法对33例(60眼)干性AMD患者和18例(30眼)正常入应用稳态的闪烁光LERG和全视野暗适应闪光ERG检测。测量振幅和峰时。结果干性AMD患者LERG平均振幅显著下降，平均峰时明显延长，与正常对照组比较有显著差异。干性AMD患者全视野暗适应闪光ERG的a波、b波振幅和峰时与正常对照组无显著差异。结论干性AMD患者行LERG检测可直接了解其黄斑区视网膜外层功能，评估其病变程度有一定的临床意义。     

An adaptive ERG technique to measure normal and altered dark adaptation in the mouse

The time-course of dark adaptation provides valuable insights into the function and interactions between the rod and cone pathways in the retina. Here we describe a technique that uses the flash electroretinogram (ERG) response to probe the functional integrity of the cone and rod pathways during the dynamic process of dark adaptation in the mouse. Retinal sensitivity was estimated from the stimulus intensity required to maintain a 30 μV criterion b-wave response during a 40 min period of dark adaptation. When tracked in this manner, dark adaptation functions in WT mice depended upon the bleaching effects of initial background adaptation conditions. Altered dark adaptation functions, commensurate with the functional deficit were recorded in pigmented mice that lacked cone function (Gnat2 ^cplf3 ) and in WT mice injected with a toxin, sodium iodate (NaIO₃), which targets the retinal pigment epithelium and also has downstream effects on photoreceptors. These data demonstrate that this adaptive tracking procedure measures retinal sensitivity and the contributions of the rod and/or cone pathways during dark adaptation in both WT control and mutant mice.     

Light-adapted electroretinograms in optic nerve hypoplasia

The purpose of the study is to characterise retinal function using light-adapted electroretinograms (ERGs) in a series of young children with ONH, congenital dysplasia of retinal ganglion cells. ERGs were recorded with chloral hydrate sedation in 27 children with ONH (18 with bilateral and 9 with unilateral ONH, age 4–35 months) and an adult reference population (n = 12). Stimuli included ISCEV standard flash, oscillatory potentials (OPs) and standard flicker as well as a light-adapted luminance–response series (photopic hill). The disc diameter to disc macula (DD:DM) ratio was measured from fundus photographs. The results are eyes with ONH, classified by DD:DM, were severe (≤0.15, n = 22), moderate (0.16–0.30, n = 22), mild (0.31–0.35, n = 1), and fellow eyes (>0.35, n = 9), all had prolonged ERG implicit times and smaller i-waves than those of adults. Eyes with moderate or severe ONH also had smaller amplitudes for OPs and flicker ERGs and required stronger flashes to obtain the peak b-wave amplitude. Abnormalities of the photopic hill were a common but inconsistent feature of ONH and were not indicative of ONH severity. Abnormalities of the photopic hill of the ERG suggest that some cases of ONH may have retinal dysfunction with specific deficits in the ON or OFF pathways of the retina. ONH is a complex and heterogeneous condition that may involve dysfunction distal to the retinal ganglion cells.     

干性年龄相关黄斑变性的局部视网膜电流图研究

目的研究干性年龄相关性黄斑变性(AMD)患者的局部视网膜电流图(LERG)反应。探讨黄斑区视网膜功能损害的程度。方法对33例(60眼)干性AMD患者和18例(30眼)正常人应用稳态的闪烁光LERG和全视野暗适应闪光ERG检测，测量振幅和峰时。结果干性AMD患者LERG平均振幅显著下降，平均峰时明显延长，与正常对照组比较有显著差异。干性AMD患者全视野暗适应闪光ERG的a波、b波振幅和峰时与正常对照组无显著差异。结论干性AMD患者行LERG检测可直接了解其黄斑区视网膜外层功能．评估其病变程度有一定的临床意义。     

CNGB3 mutations cause severe rod dysfunction

Purpose: Congenital achromatopsia or rod monochromatism is a rare autosomal recessive condition defined by a severe loss of cone photoreceptor function in which rods purportedly retain normal or near-to-normal function. This report describes the results of electroretinography in two siblings with CNGB3-associated achromatopsia.

Methods: Full field light- and dark-adapted electroretinograms (ERGs) were recorded using standard protocols detailed by the International Society for Clinical Electrophysiology of Vision (ISCEV). We also examined rod-mediated ERGs using series of stimuli that varied over a 6 log unit range of retinal illuminances (?1.9–3.5 log scotopic trolands).

Results: Dark-adapted ERGs in achromatopsia patients exhibited severely reduced b-wave amplitudes with abnormal b:a ratios (1.3 and 0.6). In comparison, the reduction in a-wave amplitude was less marked. The rod-mediated ERG took on an electronegative appearance at high-stimulus illuminances.

Conclusion: Although the defect that causes achromatopsia is primarily in the cone photoreceptors, our results reveal an accompanying disruption of rod function that is more severe than has previously been reported. The differential effects on the b-wave relative to the a-wave points to an inner-retinal locus for the disruption of rod function in these patients.     

ON- and OFF-response of the photopic electroretinogram in relation to stimulus characteristics

The purpose of this study was to document the standard full field electroretinographic (ERG) and wide field multifocal electroretinographic (WF-mfERG) findings in eyes with recent onset hemi-retinal vein occlusion (HRVO) and to compare the electro-diagnostic findings in the affected and fellow eyes with reference to normative data. Eight patients with HRVO were assessed using ERG and WF-mfERG. WF-mfERG first order responses from the affected hemi-retinae and the unaffected hemi-retinae in each affected eye were compared. WF-mfERG responses from each affected hemi-retina and from the symmetrical hemi-retina of each fellow eye were compared. ERG responses between affected and unaffected eyes were also compared. All electrodiagnostic tests were compared to normative data (5–95% confidence limits derived from age-related controls). WF-mfERG P1 and N1 implicit times were greater for the affected hemi-retinae than for the unaffected hemi-retinae (p <0.05). WF-mfERG N1 and P1 implicit times were prolonged (p < 0.05) and WF-mfERG P1/N1 amplitude ratios were significantly reduced (p < 0.05) for the affected eyes when compared with the fellow eyes. Maximal b-wave, cone b-wave and flicker implicit times were prolonged (p < 0.05) when comparing affected and fellow eyes. These results indicate that retinal injury due to HRVO culminates in significant delay of both ERG and WF-mfERG implicit times. These results suggest that WF-mfERG in combination with ERG may have a role in the management of HRVO.     

吲哚青绿血管造影对视网膜电图的影响

目的探讨吲哚青绿血管造影(ndocy anine green angiography,ICGA)否对视网膜电图(lectroretinogram, ERG)生影响。方法采用Topcon 50IA眼底照相机行ICGA,随机抽取20例38只眼,采用NeuropackⅡ电生理记录仪检测ICGA 前后全视野ERG反应。结果38只眼ICGA前、后全视野ERG暗视视杆细胞反应的b波潜伏期、振幅及最大反应a、b波潜 伏期、振幅和明视a、b波潜伏期、振幅的差异均无显著性的意义(P>0.05)。结论ICGA对ERG各反应不产生明显影响,ERG可于ICGA后进行检测。(中华眼底病杂志,2001,17:284-285)     

The effects of vigabatrin on electrophysiology and visual fields in epileptics: a controlled study with a discussion of possible mechanisms

Purpose: To compare the visual electrophysiology and visual fields of patients taking vigabatrin to those of a control group of epileptics on other anti-epileptic drugs (AEDs). Methods: Fourteen epileptics treated with vigabatrin and 10 control patients treated with other AEDs underwent ERG and EOG. Goldmann visual fields were performed and analysed using standard software to measure areas contained within I4e isopters. Results: The cone and rod b-waves of the ERG, the oscillatory potential amplitudes and Arden indices were reduced in vigabatrin-treated subjects and the oscillatory potentials delayed. The Arden indices were reduced due to an increased dark trough. The areas contained within the I4e isopter of vigabatrin treated subjects were reduced compared to the control group and these areas correlated well with oscillatory potential amplitudes and b-wave amplitudes in the vigabatrin group only. Conclusions:The use of vigabatrin is associated with a reduction of the ERG cone b-wave amplitude and oscillatory potentials which correlates with visual field loss. The Arden ratio is reduced in subjects taking vigabatrin but may recover after cessation. However, visual loss may persist in the presence of a recovered EOG. These findings suggest further effects of the drug than those mediated by GABA receptors, and support the contention that the cause of the field loss may be at least in part due to retinal effects. Possible mechanisms are discussed.     

Retinal safety of a new fluoroquinolone,pradofloxacin, in cats: assessment with electroretinography

Purpose To investigate the safety of a new fluoroquinolone, pradofloxacin, on the cat retina using electroretinogram. Methods Ganzfeld ERGs were recorded in 40 cats treated orally for 23 days in 4 groups: CTRL (n = 9): placebo-vehicle; PRADO30 (n = 10): pradofloxacin 30 mg/kg/day; PRADO50 (n = 14): pradofloxacin 50 mg/kg/day; and ENRO30 (n = 7): enrofloxacin at toxic doses of 30 mg/kg/day. ERG was performed before treatment and once weekly during the treatment period. An extended ISCEV protocol with addition of 8 steps of increasing luminance in dark adapted condition was carried out to assess: V _max (saturated scotopic b-wave amplitude) and k (luminance inducing V _max/2). OCT and retinal histological changes were also investigated. Results Pradofloxacin showed no effects in respect to rod b-wave, V _max, k and maximum scotopic a-wave (P > 0.05). Oscillatory potentials, cone ERG and flicker were also unaltered (P > 0.05). Rod b-wave was undetectable after treatment in ENRO30 group, V _max was reduced to 10.5% of the baseline (P < 0.05), accompanied by an increase of k by 1 log cd s/m2 (P < 0.05). Oscillatory potentials, cone b-wave amplitude and 30 Hz flicker amplitude were reduced to 8.3%, 58.9% and 37.4% of the baseline, respectively (P < 0.05). Effects were also seen in OCT and retinal histology starting within one week after the start of treatment and thereafter remaining stable. Conclusion Pradofloxacin at 6 and 10 times the recommended doses was shown to have no retinal toxic effects in cats, neither on rod or cone function with ERG.     

The b-wave of the dark adapted flash electroretinogram in patients with advanced asymmetrical glaucoma and normal subjects

AIMS: To evaluate whether the b-wave of the dark adapted flash electroretinogram (ERG) is affected by glaucomatous damage. METHODS: ERGs were recorded in 35 patients aged 33-65 years with advanced asymmetrical glaucomas (interocular difference of perimetric defects (mean deviation) >2 dB between the two fellow eyes of the glaucoma patients, primary and secondary open angle and low tension glaucomas) and 17 normal subjects matched for age and sex using white flashes of a xenon discharge tube in a Ganzfeld stimulator. After 30 minutes of dark adaptation luminance response functions were obtained using flashes of increasing scotopic luminance (highest 9.4 cd/s/m2, lowest 5.5 log units below it). The parameters Vmax, n, and K of the Naka-Rushton equation were computed from the measurement values based on the usual fitting procedure. These parameters, together with b-wave amplitudes and implicit times for all flash intensities, were compared interocularly and between the normal subjects and those with glaucoma. Correlations were computed between interocular differences of the mean deviation and interocular differences of Vmax, n, K, b-wave amplitudes, and implicit times between the two fellow eyes of the patients with asymmetrical glaucomatous damage. RESULTS: Implicit times were significantly longer (p<0.005) in the glaucoma patients than in the normal group for flash intensities of 9.4, 5.3, 1.7, 0.53, and 0.17 cd/s/m2. b-Wave amplitudes did not differ significantly between the two study groups. Comparing the two fellow eyes of each patient with glaucoma, Vmax was significantly higher in the less damaged eye than in the more damaged eye. The interocular differences in the mean deviation correlated significantly with the interocular differences in the b-wave amplitudes, implicit times, and Vmax. CONCLUSIONS: These results suggest that glaucomas can lead to electrophysiologically measurable damage of the inner nuclear layer.