Effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema

Abstract

Purpose: To evaluate the effects of subthreshold diode micropulse laser photocoagulation on treating patients with refractory diabetic macular edema (DME). Methods: This randomized clinical trial recruited patients with DME in both eyes that were resistant to treatment with intravitreal bevacizumab (IVB). The eyes were randomly divided into two groups who received laser therapy and IVB, or IVB alone. Subthreshold diode micropulse laser photocoagulation and IVB injection were administered in one eye, and an IVB injection was administered in the second eye. IVB injections were repeated in both eyes within one month and two months after the first injection. Best corrected visual acuity (BCVA) logarithm of the minimum angle of resolution (logMAR) and central macular thickness (CMT) were measured before, within a month, and three months after start of intervention. Results: In this study, 42 eyes of 21 patients were evaluated. The mean age of patients was 60.86 ± 8.57 years. Ten patients (47.6%) were male. Within-group analysis showed a significant decreased in BCVA logMAR in the laser + IVB group reflecting improvement in visual acuity (VA) (P < 0.001); it increased in the control group during study reflecting more vision loss (P = 0.01). In the laser + IVB group, a significant decrease in mean ± standard deviation (SD) CMT at 3 months compared to baseline was observed (baseline: 513 ± 126.29 vs. three months: 408.1 ± 95.28; P < 0.001). The mean ± SD CMT was significantly lower in the laser + IVB group of eyes than in the control group three months after intervention (P = 0.02). Conclusion: Using subthreshold diode micropulse laser photocoagulation in combination with IVB can significantly reduce CMT and improve BCVA in patients with refractory DME. Keywords: Lasers, Macular edema, Diabetic retinopathy, Photocoagulation