Subthreshold micropulse diode laser photocoagulation for diabetic macular edema in Japanese patients

Abstract

Purpose: To assess the efficacy and safety of subthreshold micropulse diode laser photocoagulation for diabetic macular edema (ME).

Design: Prospective, nonrandomized interventional case series.

Setting: Institutional.

Patients: Thirty-six consecutive diabetic patients (43 eyes) with clinically significant ME and a central macular thickness (CMT) <600 microm by optical coherence tomography.

Observation procedures: Subthreshold micropulse diode laser photocoagulation was done with a 15% duty cycle (0.2 to 0.3 sec; 200 microm) at 50% to 90% of the burn threshold energy. The treated area was monitored on color images for 12 months.

Main outcome measures: CMT, best-corrected visual acuity (BCVA), and total macular volume at 3 months.

Results: After 3 months, there was a significant reduction of CMT (P = .05, paired t test), but the changes of BCVA and macular volume were not significant. The preoperative CMT, BCVA (logarithm of the minimal angle of resolution; logMAR), and macular volume were 341.8 +/- 119.0 microm, 0.12 +/- 0.20, and 8.763 +/- 1.605 mm(3) respectively, vs 300.7 +/- 124.1 microm, 0.12 +/- 0.21, and 8.636 +/- 1.408 mm(3) at 3 months. CMT decreased significantly from 1 month (P = .015, Friedman test). Visual acuity was improved or maintained within 0.2 logMAR for 12 months in 94.7% of the patients. No obvious laser scars were detected in any patient.

Conclusions: In patients with moderate diabetic ME, subthreshold micropulse diode laser photocoagulation controls ME and maintains visual acuity with minimal retinal damage. These findings confirm the efficacy of this method for Japanese patients.