The electroretinogram after peripheral retinal ablation in diabetic retinopathy.

The electroretinograms (ERGs) from 14 patients with proliferative diabetic retinopathy were recorded before and after peripheral retinal ablation by photocoagulation. It was expected that the ERG would be reduced in amplitude in proportion to the area of retina destroyed by the treatment. The ablation treatment, carried out in a standard manner in each patient, resulted in a decrease of ERG amplitude that varied from 10 to 95% among the patients, and caused an increase in ERG latency and implicit time in several patients. This suggests a wide variability in the area of retina affected by the treatment, and the possibility of an effect of the procedure on adjacent untreated retina in some diabetic patients.