Retinal function in diabetic macular edema after focal laser photocoagulation

PURPOSE. To assess the effects of focal photocoagulation on retinal functio n in the macular and perimacular areas in patients with diabetes who have c linically significant macular edema. METHODS. Eleven patients were assessed after focal laser treatment. Multifo cal electroretinogram (ERG) and full-field ERG techniques were used to eval uate the effects of treatment on macular, paramacular, and peripheral retin al function. A modified visual field technique was used to obtain local thr eshold fields. The posttreatment results were compared with pretreatment re sults. Changes in local ERG response amplitudes and implicit times were cal culated for each patient and presented as difference fields. The changes in local ERG responses were compared with the changes in local field sensitiv ity. RESULTS. After treatment, the results of the psychophysical tests suggested little or no change in visual function, but changes in retinal function we re observed with the multifocal ERG technique. Local ERG responses showed i ncreases in implicit time and decreases in amplitude, compared with pretrea tment values. Timing was affected more than amplitude. CONCLUSIONS. The results suggest that focal treatment produces changes in r etinal function, and these changes are not restricted to the treated macula r area.