Choroidal structure as predictor of macular changes and visual outcomes after panretinal photocoagulation in eyes with very severe NPDR and early PDR without center-involving DME

Panretinal photocoagulation (PRP) is widely used for advanced diabetic retinopathy, yet its effects on retinal and choroidal architecture remain incompletely characterized. This prospective observational study evaluated retinal and choroidal structural changes after PRP in 39 eyes of 21 patients with very severe non-proliferative diabetic retinopathy (NPDR) or early proliferative diabetic retinopathy (PDR) without center-involving diabetic macular edema (DME) using enhanced depth imaging optical coherence tomography (EDI-OCT) at baseline and at 1 and 3 months post-treatment. Quantitative parameters included foveal and whole macular thickness, subfoveal choroidal thickness (SFCT), and choroidal vascularity index (CVI), while intraretinal fluid (IRF) and hyperreflective foci (HF) were evaluated by masked graders. Foveal thickness increased significantly at 1 month (p = 0.017) and 3 months (p = 0.032), and whole macular thickness increased at 1 month (p < 0.001), with stable visual acuity. SFCT increase at 1 month was associated with retinal thickening (B = 0.154, p = 0.008). CVI elevation at 1 month correlated with visual improvement (B = − 0.015, p = 0.013), whereas CVI increase at 3 months was associated with visual decline (B = 0.019, p = 0.007). SFCT increase at 3 months was significantly associated with IRF formation (p = 0.016), indicating that EDI-OCT-derived choroidal metrics may serve as predictive biomarkers of post-PRP macular structural and functional responses.