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Background/aims To characterise the distribution of retinal non-perfusion and its relationship with neovascularisation elsewhere (NVE) and visual acuity (VA) in referable diabetic retinopathy (DR) using ultra-widefield fluorescein angiography (UWFA). Methods Eyes with treatment-naïve moderately severe non-proliferative DR (NPDR) to proliferative diabetic retinopathy (PDR) (Diabetic Retinopathy Severity Scale (DRSS) level 43–60) with available UWFA were included in this study. Total and zonal non-perfusion and NVE area were manually delineated across concentric zones (central 1–10 mm, extended posterior >10–20 mm and mid-peripheral >20–30 mm diameter). The Non-Perfusion Index (NPI) was calculated as the ratio of non-perfused area to total area per zone. Associations between NPI, NVE, DR severity and best-recorded VA (BRVA) were assessed. Results A total of 133 eyes (60.9% NPDR, 39.1% PDR) were analysed. The highest NPI occurred in the mid-periphery (20–30 mm) and posterior pole (15–20 mm) zones, with nasal preponderance. NVE was most frequently observed in the posterior pole (66%) and nasal quadrants. Central and mid-peripheral NPI correlated with NVE area in corresponding zones, showing quadrant-specific associations. Receiver operating characteristic analysis identified a total NPI threshold of 0.23 to differentiate PDR from NPDR (area under the curve=0.798), with the lowest threshold in the superior quadrant. Neither NPI nor NVE area correlated with BRVA. Conclusion NVE represents a localised response to adjacent ischaemia predominantly affecting the nasal and extended posterior retina. NPI threshold of 0.23 distinguishes proliferative from non-proliferative stages, with the superior quadrant showing greater susceptibility to NVE at lower ischaemic levels. No significant correlation found between NPI, NVE area and visual acuity.
Khalid et al. (Thu,) studied this question.