Quantitative evaluation of electroretinogram before cataract surgery.

The ERGs (electroretinogram) of dense mature cataractous eyes were compared with those of the fellow eyes with good visual acuity in 22 senile patients who showed normal preoperative ERG. The mean amplitudes of the a- and b-waves were slightly reduced in the cataractous eyes as compared to those of the fellow eyes, but the difference was not significant. The light-absorbing effect of the cataract based on the a- and b-wave amplitudes was 0.5 log units. Another group of 13 eyes with senile mature cataract showed abnormal preoperative ERG. Chorioretinal atrophy was the most common cause of the subnormal ERG. Postoperative visual acuity was lower in cataractous eyes with subnormal ERGs than in eyes with normal ERGs. Despite the fact that it does not always reflect the macular function and the visual pathway, the ERG still remains a reliable guide in evaluating the visual prognosis before cataract surgery.