Original Articles
Abnormal focal macular electroretinograms in eyes with idiopathic epimacular membrane

https://doi.org/10.1016/S0002-9394(98)00447-4Get rights and content

Abstract

PURPOSE: To study the functional state of the retina beneath an epimacular membrane by means of focal macular electroretinography.

METHODS: Focal macular electroretinograms of 30 consecutive patients (age 25 to 75 years) with unilateral idiopathic epimacular membrane were recorded prospectively. The amplitudes and implicit times of the a and b waves and the oscillatory potentials (O1, O2, O3) recorded from the eye with idiopathic epimacular membrane were compared with those of the normal fellow eye.

RESULTS: There was a statistically significant reduction in the amplitude of the a wave (P < .001), the b wave (P < .001), and the oscillatory potentials (O1 + O2 + O3; P < .001) of the affected eyes. The reduction of the b-wave amplitude was significantly greater than that of the a wave, resulting in a lower b/a wave ratio (P = .003) in the affected eyes. The reduction in the amplitude of the oscillatory potentials was significantly greater than that of the other two components (P < .001). The implicit times were significantly prolonged for the a wave (P < .001), the b wave (P = .004), and O3 (P < .001). There was a significant correlation between relative b-wave amplitude (affected/normal fellow eye) and the visual acuity (r = −0.50, P = .007). These findings were similar to those we reported for eyes with aphakic cystoid macular edema.

CONCLUSIONS: The focal macular electroretinograms in eyes with epimacular membrane disclosed abnormalities that were similar to those of eyes with cystoid macular edema. This suggests that the epimacular membrane probably induced damage to the neurons in the inner retinal layers. Dysfunction of these neurons is one possible cause of visual impairment in this disease.

Section snippets

Methods

Focal electroretinograms, macular a and b waves, and oscillatory potentials were recorded prospectively from 30 consecutive patients with unilateral idiopathic epimacular membrane. The ages of the patients were 25 to 75 years (mean ± SD, 58.3 ± 10.5 years). Because our previous studies12, 13, 14 demonstrated wide interindividual variations in oscillatory potentials but a high correlation between the two eyes for all components, the normal fellow eye served as the control. The relative

Results

A comparison of the focal macular electroretinograms recorded from the normal fellow eyes with those from an age-matched control group (30 to 70 years, 50 men and 31 women) showed no significant difference in the amplitudes of the a and b waves, and the oscillatory potentials (a wave, P = .91; b wave, P = .69; oscillatory potentials [O1 + O2 + O3], P = .77). In the same groups, no significant difference was found for the implicit times for the same components (a wave, P = .75; b wave, P = .84;

Discussion

The results of our study can be summarized as follows: (1) The amplitudes of the a and b waves and the oscillatory potentials were significantly reduced, and the implicit times of these components were significantly prolonged. (2) The reduction of the b wave was significantly greater than that of the a wave, which resulted in a lower b/a ratio. (3) The reduction in the amplitude of oscillatory potentials was significantly greater than that of other two waves. These findings indicate substantial

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    This study was supported by Grant-in-Aid No. 62480362 from the Ministry of Education, Science and Culture, Japan.

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