Effect of panretinal photocoagulation on macular visual function and choroid structure in diabetic retinopathy

Purpose Based on optical coherence tomography angiography (OCTA) and microperimetry, this study aims to analyze the effects of panretinal photocoagulation (PRP) on macular visual function and choroidal structure in patients with severe non-proliferative diabetic retinopathy (NPDR) and early proliferative diabetic retinopathy (PDR). Methods A retrospective non-randomized controlled study was conducted, enrolling 52 patients (66 eyes) with treatment-naïve diabetic retinopathy (DR). Based on disease severity, patients were divided into two groups: a severe NPDR group (26 patients, 32 eyes) and an early PDR group (26 patients, 34 eyes). All patients underwent PRP treatment. Data on best corrected visual acuity (BCVA), retinal mean sensitivity (RMS) in the macular area, choroidal vascularity index (CVI), and choroidal thickness (CT) in the macular area were collected before treatment and at 1, 3, and 6 months after treatment. Treatment-related complications were also observed in both groups. Results During the follow-up period, there was no statistically significant difference in the trends of BCVA and macular RMS changes before and after PRP treatment between the two groups. BCVA in both groups decreased at 1 month after treatment, with a statistically significant difference ( P  < 0.001), and returned to baseline levels by 6 months. RMS in both groups decreased after treatment, with a statistically significant difference ( P  < 0.001). During the follow-up period, there was a statistically significant difference in the trend of CVI changes between the two groups ( P  < 0.001). In the severe NPDR group, CVI decreased at 1 and 3 months after treatment, with a statistically significant difference ( P  < 0.001), and returned to baseline levels by 6 months. In the early PDR group, CVI decreased after PRP treatment compared to before treatment, with a statistically significant difference ( P  < 0.001). During the follow-up period, there was no statistically significant difference in the trend of CT changes between the two groups. CT in both groups decreased after PRP treatment compared to before treatment, with a statistically significant difference ( P  < 0.001). Before and after PRP treatment, BCVA was positively correlated with RMS, with statistically significant differences ( P  < 0.001). RMS was positively correlated with CVI, with statistically significant differences ( P  < 0.05). No significant correlations were observed among changes in other parameters. Conclusion During the 6-month follow-up period, BCVA gradually recovered to baseline levels, indicating minimal long-term impact of PRP on central vision. RMS values showed a mild decrease, suggesting some influence of PRP on macular retinal function. The CVI in the early PDR group was significantly lower than that in the severe NPDR group, implying that the effect of PRP on choroidal microcirculation may be associated with disease stage. Additionally, a significant reduction in CT was observed in both patient groups, demonstrating a substantial impact of PRP on choroidal thickness.