AIM: To explore the clinical application effect of 532 laser subthreshold photocoagulation for diabetic macular edema(DEM).

METHODS: Fifty-seven eyes of 32 diabetes patients with diffuse macular edema of non-proliferative diabetic retinopathy were randomized to experimental group and control group. The subthreshold laser photocoagulation was performed in the experimental group, and the threshold laser photocoagulation in control group. The effect evaluation of photocoagulation included visual acuity, fundus examination, optical coherence tomography at pre-treatment and various times after treatment(1 week, 1 month, 3 months), and all patients underwent fluoreseein angiography at pre-treatment and the 3^rd month after treatment.

RESULTS: At the first month after photocoagulation, in the experimental group, the eye visual acuity improved accounted for 11.1%, unchanged accounted for 66.7%, vision loss accounted for 22.2%, and the eyes visual acuity improved accounted for 13.3%, unchanged accounted for 63.3%, vision loss accounted for 23.3% in the control group. There were no statistical differences in visual acuity improvement in two groups. At the first month after photocoagulation, in the experimental group, macular edema completely absorbed accounted for 0 cases, partial absorbed accounted for 40.7%, no absorbed accounted for 59.3%, and in the control group was 6.7%, 53.3%, and 40.0%. Macular edema was absorbed better in the control group than in the experimental group, but the difference was not statistically significant(P>0.05). At 3^rd month after laser treatment, the data of macular edema absorbed and visual acuity improved were similar in two groups, the difference was not statistically significant(P>0.05).

CONCLUSION: The subthreshold photocoagulation for DME is as effective as classical grid laser treatment, and this method is very safe.