Subthreshold Yellow micropulse laser for treatment of diabetic macular edema: comparison between fixed and variable treatment regimen

PURPOSE: To compare the efficacy between fixed and variable treatment regimens of subthreshold yellow micropulse laser for the treatment of diabetic macular edema. METHODS: This is a retrospective, comparative, 12-month study of 39 eyes: 24 eyes received F-SMPL treatment and 15 eyes underwent V-SMPL, all eyes were followed up for 12 months. SMPL was performed with the following parameters: 100 μm spot size on slit lamp, 5% duty cycle of 0.2 seconds and 250 mW power. To choose the power of the V-SMPL group, continuous laser power was titrated to a barely visible burn and then switched to MicroPulse mode, multiplying the test burn power by 4 and using a 5% duty cycle of 0.2 sec. Main outcomes included changes in CMT and BCVA. RESULTS: At baseline, the mean LogMAR BCVA was 0.297±0.431 in the V-SMPL group and 0.228±0.341 in the F-SMPL group. At the end of follow-up, the mean Log MAR BCVA was 0.289±0.473(p=0.785) and 0.245±0.376(p=0.480) in the V-SMPL and F-SMPL group respectively. Similarly, CMT decreased in both groups after treatment; at baseline the mean CMT was 371.06±37.8 in the V-MPL group and improved to 325.60±110.0 µm(p=0.025) at the end of the follow-ups, while it was 342.30±35.4 in the F-SMPL group and improved to 308.51 ± 67.5(p=0.037). CONCLUSIONS: Both treatment regimens are effective for the treatment of mild center involving diabetic macular edema: fixed treatment appears more suitable minimizing treatment time and reducing the possible errors due to wrong titration in the switch from continuous to micropulse mode