Effects of different degrees of cataract on the multifocal electroretinogram

Aim. To study the effect of different degrees of nuclear cataract on the multifocal electroretinogram (mfERG). Methods. mfERGs were recorded from 30 elderly subjects with very mild, mild, or moderate nuclear cataracts using a VERIS System (version 4.1). The subjects were divided into three groups (10 in each group) according to their degree of nuclear cataracts as classified according to the Lens Opacities Classification System III (LOCS III). No subjects had any significant eye disease or degenerative changes except for cataracts. The mfERG responses were grouped into six concentric rings for analysis. Both the N1 and P1 amplitudes and the latencies of N1 and P1 of first-order responses were used for analysis. Results. Amplitudes of N1 and P1 from the central retina (14°) were significantly reduced in patients with mild or moderate cataract when compared with subjects with very mild cataract. However, there was no significant reduction of N1 and P1 amplitudes in the paracentral retina (14-40°). There was no difference in the latencies of N1 and P1 in these three groups of subjects. Conclusions. The mfERG responses from the central retina (central 14°) were affected by the severity of cataract, but responses from the paracentral retina (14-40°) were not affected. This suggests that in interpreting the mfERG in subjects with mild or moderate cataract subjects some care should be taken as reduced amplitudes (N1 and P1) will be expected from the central retina.