Macular superficial capillary plexus perfusion density after panretinal photocoagulation in diabetic retinopathy: an OCT angiography study

Abstract Purpose To evaluate macular superficial capillary plexus (SCP) perfusion density (PD) measured by optical coherence tomography angiography (OCTA) in healthy eyes and eyes with diabetic retinopathy (DR) previously treated with panretinal photocoagulation (PRP), and to determine whether different diabetic macular phenotypes exhibit distinct patterns of residual microvascular impairment. Methods This cross-sectional, comparative observational study included 97 eyes that underwent 6 × 6 mm macular OCTA imaging using the Cirrus HD-OCT 5000 AngioPlex system. Fifty-six healthy eyes served as controls, whereas 41 PRP-treated diabetic eyes were classified according to macular status into no diabetic macular edema (NDME, n = 13), diabetic macular edema (DME, n = 13), and ischemic maculopathy (IM, n = 15). SCP perfusion density was quantified in four ETDRS regions and eight ETDRS sectors. Generalized estimating equations (GEE) were used to compare perfusion density while accounting for within-subject inter-eye correlation and adjusting for age and OCTA image quality. Results In unadjusted analyses, complete-grid SCP PD was higher in healthy eyes than in PRP-treated diabetic eyes. After adjustment for age, OCTA image quality, and inter-eye correlation, the principal difference was driven by the IM phenotype. Among diabetic eyes, complete-grid SCP PD remained significantly lower in IM than in NDME (adjusted difference, -0.048; P < 0.001) and DME (adjusted difference, -0.050; P < 0.001), whereas NDME and DME did not differ ( P = 0.875). Central SCP PD did not differ significantly among diabetic phenotypes. OCTA image quality was strongly associated with complete-grid SCP PD, whereas age was not significant in the adjusted diabetic model. Conclusions In eyes with DR previously treated with PRP, macular SCP perfusion differed according to macular phenotype, with the most pronounced residual impairment in eyes classified as having ischemic maculopathy. Regional OCTA metrics may provide information not captured by central perfusion measurements alone. Because this study is cross-sectional and lacks pre-PRP OCTA measurements, the findings characterize residual perfusion status in treated eyes and should not be interpreted as demonstrating a causal effect of PRP on macular perfusion.