[Treatment by horseshoe pattern photocoagulation of diabetic cystoid macular edema]

Eighty cases Diabetic Cystoid Macular Edema, with or without central spaces underwent photocoagulation from 1978 to 1989 using a horseshoe or ring pattern. Initial visual acuity ranged from 20/25 for far vision and 20/20 for near vision to a central scotoma, with an average of 20/60 for far vision and 20/50 for near vision. As initial treatment, we performed 63 horseshoe pattern and 13 ring pattern photocoagulation around the macula; an additional photocoagulation was carried out in 29 cases, one month to seven years later (average of 18.3 months), either on medial to the previous treatment (18), or closing the initial horseshoe pattern (10) or resulting in focal treatment (13), or associating any of these three. The cystoid macular edema disappeared in 47 cases, decreased in 15 cases, and remained in 14 cases, with a follow up ranging from 6 months to 10.5 years (average of 41.6 months). The post laser visual acuity range from 20/25 for far vision and 20/20 for near vision, to a central scotoma again, with an average of 20/60 for far and near visions. During the follow up various reasons of visual impairment were observed: cataract, intravitreal hemorrhage, epiretinal membrane, macular pucker and macular ischemia. Our results compared with the published ones concerning a grid pattern photocoagulation are encouraging. It is very important to stress that this photocoagulation is only aimed toward the macular edema itself: if necessary it should be associated with a grid pattern or a focal photocoagulation aimed toward extramacular edema.