Nondamaging retinal laser therapy in recurrent diabetic macular edema after anti-vegf injections

Abstract

Background/aim: Subthreshold yellow nondamaging retinal laser therapy (NRT) could provide a greater safety profile when compared to conventional laser methods. NRT may also improve diabetic macular edema (DME). This study aims to assess whether the severity of DME affects the efficacy of subthreshold yellow NRT. Materials and methods: The study included 70 eyes that had previously been treated with ranibizumab for DME and then developed recurrent macular edema, which was treated with NRT once. The central foveal thickness (CFT) and best-corrected visual acuity (BCVA) were evaluated retrospectively 2 months following the NRT. The eyes in the study were divided into 4 different groups according to the baseline CFT values. The initial CFT was 250–300 μm in Group 1 (n = 26), 301–400 μm in Group 2 (n = 24), and >401 μm in Group 3 (n = 20). Group 4 (n = 20) included control subjects with 250–300 µm CFT, diagnosed with DME, and not previously treated. The alterations in the BCVA and CFT were measured. Results: In the study, it was determined that 45 right eyes and 45 left eyes were involved. Statistically significant decrements (42.84 μm reduction) in CFT were detected only in the Group 1 (p = 0.01). There was no significant improvement in CFT within Group 2, 3 and 4 (p = 0.29, p = 0.73, p = 0.22, respectively). Solely Group 1 had statistically significant improvement (from 0.54 to 0.39 LogMAR) in BCVA (p = 0.01), while groups 2, 3 and 4 had no improvement at all (p = 0.74, p = 0.96, p = 0.66 respectively). Conclusions: Based on the results, NRT provided an improvement in BCVA and CFT in eyes with CFT less than 300 µm at the short-term follow-up. However, CFT and BCVA outcomes after NRT were inferior to those achieved after previous ranibizumab treatment. No positive effect of NRT was not observed in patients with moderate and severe macular edema in DME treatment.