Spontaneous evolution and photocoagulation of diabetic cystoid macular edema.

Cystoid macular edema (CME) causes progressive visual impairment in diabetic patients and its treatment by photocoagulation remains unsatisfactory. We observed its spontaneous evolution for 3 years in 31 eyes. CME resolved in 9 eyes, was fluctuant in 16 and worsened in 7. Mean group visual acuity (VA) remained unchanged. Two modalities of photocoagulation were studied. In 27 eyes exhibiting CME combined with circinate exudates (group 1), extramacular focal photocoagulation was applied to the center of the exudates. Exudates disappeared from 23 eyes and CME from 12 eyes. Mean group VA remained unchanged. In 24 eyes with CME but without exudates (group 2), perifoveolar grid photocoagulation was applied over the CME area. CME disappeared from 15 eyes. Mean VA remained unchanged. These results show that CME with exudates requires a two-step treatment, comprising first focal photocoagulation, which clears exudates and often improves CME, and second--but only if CME persists and VA is below 0.5- perifoveolar grid photocoagulation, which often clears CME and stabilizes VA.