Assessment of Relationship between Neovascularization Type Using Wide Field Optical Coherence Tomography Angiography in Eyes with Proliferative Diabetic Retinopathy

Abstract

Abstract Introduction Retinal neovascularization in proliferative diabetic retinopathy (PDR) presents with varying morphology and clinical implications. This study aims to classify retinal neovascularization into subtypes and assess their correlation with ischemic index using widefield optical coherence tomography (OCT) angiography. Methods This retrospective observational study included 50 treatment-naïve patients (84 eyes) with PDR who underwent baseline widefield fundus photography (CLARUS 500™) and widefield optical coherence tomography angiography (WF-OCTA; Plex Elite 9000) between January 2022 and June 2024. Quantitative analysis of WF-OCTA images assessed capillary nonperfusion (CNP), ischemic index (ISI), and three neovascularization (NV) subtypes: type 1 NV (flat, intraretinal or subinternal limiting membrane growth), type 2 NV (preretinal proliferation extending into the vitreous), and type 3 NV (a combination of types 1 and 2 features, showing both flat and protruding components). Two clinicians manually delineated capillary nonperfusion (CNP) using ImageJ software. Neovascularization (NV) was classified by subtype and location (posterior versus mid-periphery). Ischemic index (ISI), nonperfusion area, best corrected visual acuity (BCVA), and the need for adjunctive interventions (additional laser or vitreoretinal surgery) were correlated with treatment response to panretinal photocoagulation (PRP). Results Type 1 neovascularization was most frequent (42.1%), with a mean ischemic index (ISI) of 0.19 ± 0.17. Type 3 neovascularization showed the highest ISI (0.27 ± 0.07) and largest nonperfusion area (36.66 mm2 ± 10.24). Best corrected visual acuity (BCVA) improved in 58% of patients after panretinal photocoagulation, with type 3 showing the greatest improvement. Adjunct laser therapy was required more frequently for type 2 (13 cases) following standard panretinal photocoagulation. However, type 3 required the least supplemental laser. Conclusions WF-OCTA proves valuable in the assessment of disease severity and its extent, along with possible implications on planning the intervention for PDR.

Keywords

• Diabetic retinopathy
• Neovascularization
• Optical coherence tomography angiography
• Ischemic index
• Proliferative diabetic retinopathy