Micropulse Diode Laser Subthreshold Photocoagulation For Diabetic Macular Edema

Objective To determine the effectiveness and safety of micropulse diode laser(810nm)subthreshold(invisible) photocoagulation on diabetic macular edema(DME), aimed toinvestigate a new method for diabetic macular edema.Methods Forty eyes of 35 diabetic patients with clinically significant diabetic macularedema were randomized to four groups which were micropulse laser subthresholdtreatment group, short-pulse laser subthreshold treatment group, long-pulse lasersubthreshold treatment group and classic grid laser treatment group. Eyegroundevaluation included visual acuity, anterior segment examination, intraocular pressure andophthalmoscopy at pre-treatment and various times after treatment (1, 2, 3 weeks, 1, 2, 3months), and all of patients underwent fluorescein angiography at pre-treatment and the3rd months after treatment.Results 1. Visual acuity :The visual acuity of most patients had various loss at the1st, 2nd and 3rd week after laser treatment compared with pre-treatment, there wasespecially obvious drop in the classic grid laser treatment group. The symptom lightenedobviously at the 1st month after treatment, and the visual acuity of the cases was steady onthe whole at the 2nd month. At the 3rd month there was no statistical difference in visualacuity among the four groups(P＞0.05), and the comparison of visual improvement, visualloss showed no statistical difference among the four groups (P＞0.05).2.The changes of eyeground:After 1 week most lesions were visible as yellow whichwere RPE depigmentation in micropulse laser subthreshold treatment group, short-pulselaser subthreshold treatment group and long-pulse laser subthreshold treatment group. Then the scar of photocoagulation disappeared gradually. After 3 months some ofthe lesions were visible at hyperpigmented areas but most were not. After 1 monthpigment scar appeared in classic grid laser treatment group and pigmentation aggravatedgradually. After 2 months a part of scar fused. At 1st month after treatment macularedema reduced in some cases, which were showed by decrease of hard exudates andclosure of microaneurysms.3. Elimination of macular edema: At 3rd month after laser treatment macular edemaabsorbed compared with pre-treatment in most cases. In micropulse laser subthresholdtreatment group elimination of DME appeared in 2 eyes(20%), reduction-of DMEappeared in 6 eyes(60%), and unchanged or aggravation of DME appeared in 2 eyes(20%);in short-pulse laser subthreshold treatment group elimination of DME appeared in 3eyes(30%), reduction of DME appeared in 6 eyes(60%), and unchanged or aggravationof DME appeared in 1 eye(10%); in long-pulse laser subthreshold treatment groupelimination of DME appeared in 1 eyes(10%), reduction of DME appeared in 5 eyes(50%),and unchanged or aggravation of DME appeared in 4 eyes(40%); in classic grid lasertreatment group elimination of DME appeared in 3 eyes(30%), reduction of DMEappeared in 5 eyes(50%), and unchanged or aggravation of DME appeared in 2eyes(20%). There was no statistical difference among the four groups (P＞0.05).Conclusion We come to the conclusion that micropulse diode laser subthresholdphotocoagulation for DME is as effective as classic grid laser treatment, and this methodis very safe, so it could be wildly used in the treatment of diabetic macular edma.