120° Widefield SS-OCTA Assessment of Retinal and Choroidal Vascular Changes After Panretinal Photocoagulation in Severe NPDR

OBJECTIVE: To investigate retinal and choroidal blood vascular changes before and after panretinal photocoagulation (PRP) in severe non-proliferative diabetic retinopathy (NPDR) patients using widefield swept-source optical coherence tomography angiography (SS-OCTA) covering 120° fundus. METHODS: A prospective longitudinal study enrolled 55 patients with type 2 diabetes mellitus and severe non-proliferative diabetic retinopathy (NPDR), contributing 95 eyes scheduled for PRP, which was administered in four weekly sessions. SS-OCTA scanning (6 mm × 6 mm and 24 mm × 20 mm mode) was performed pre- and 3 months post-PRP. Quantitative parameters included foveal avascular zone (FAZ) size and vessel density (VD) of superficial retinal vessels (SRV), deep retinal vessels (DRV), choriocapillaris (CC), and large and medium choroidal vessels (LMVC). RESULTS: = .0118, respectively) before and 3 months after PRP. FAZ size and logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) remained unchanged before and 3 months after PRP. FAZ size was positively correlated with BCVA at both pre-PRP and 3-month post-PRP assessments. CONCLUSION: Widefield SS-OCTA demonstrates that PRP in severe NPDR induces layer-specific microvascular reductions, most pronounced in the deep retina and CC, concurrent with reduced VD of LMVC layer, while preserving central macular structure and function at 3 months after PRP.