Abstract

Background: Diabetic macular edema (DME) is a leading cause of visual impairment and its treatment is a public health challenge. Antiangiogenic agents are the gold standard treatment, but they are not ideal, and subthreshold laser (SL) is a viable and promising treatment in certain cases. The purpose of this study was to evaluate its usefulness in a real-world environment.
Methods: A retrospective case series of 54 eyes of 32DME patients admitted to the center treated with SL monotherapy. Treatment was performed using the EasyRet® photocoagulator with the following parameters in one session: 5% duty cycle, 200 ms pulse duration, 160 µm spot size, and barely visible.Output at 50% of threshold. A high-density pattern was then applied across the edematous region using multi-spot mode. Best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) data were obtained at baseline and approximately 3 months after treatment.
Results: 54 eyes of 32 patients were included (38% female, mean age 63.8 years). The mean time from treatment date to follow-up visit was 12±6 weeks. BCVA (Snellen transformed to logMAR) was 0.59±0.32 and 0.43±0.25 at baseline and follow-up, respectively (p=0.002). 32% had previously undergone pan-retinal photocoagulation (p = 0.011). The average laser power was 555 ± 150 mW and the number of spots was 1,109 ± 580. Intraretinal and subretinal fluid (SRF) were observed in 96 and 41% of eyes at baseline and improved in 35 and 74% of eyes, respectively, after treatment. Quantitative analysis of changes in central macular thickness (CMT) was performed in a subset of 23 eyes, of which 43% showed a greater than 10% reduction in CMT after treatment.
Conclusions: Subthreshold laser therapy is known to have RPE function as a major target that normalizes heat shock protein activation and cytokine expression. In the present study, cases of DME associated with SRF showed excellent physiological responses, whereas laser monotherapy did not respond to a reduction of intraretinal edema. BCVA and macular thickness showed a mild response, suggesting the need for combined treatment in most patients. may be a viable treatment option.