Optical coherence tomography angiography markers of neovascularisation activity in treated wet age-related macular degeneration

Abstract

Purpose : The aim of this study was to investigate three-dimensional (3D) models of choroidal neovascular (CNV) membranes using optical coherence tomography (OCT) and OCT angiography (OCT-A) in patients post-treatment for wet age-related macular degeneration (wAMD) whose OCTs showed no evidence of activity. Differences in the 2D appearance of the 3D CNVs have been associated with differences in disease progression. The more detailed morphology represented through 3D models may render additional information on disease progression, activity, and prognosis.

Methods : 27 patients were included at 16 weeks after aflibercept treatment whose OCT scans showed no remaining evidence of disease activity, but evidence of blood flow in CNV on OCTA (Spectralis, Heidelberg Engineering, Heidelberg, Germany). OCTA images were used to create 3D models of the CNVs (n = 27).

Images were processed using custom developed methods for feature extraction. The OCT-A volumes were visualised using the ImageJ 3Dviewer plugin, and the binary masks of the vessels extracted. CNV size was calculated based on 2D and 3D images and interpreted in the context of visual acuity in the ETDRS scale.

Results : 3D models were successfully generated for 9 subjects, 67% females and 33% male, with the mean age of 77 (range 59-87). The 3D modelling uncovered much larger CNV sizes compared to the 2D representation. The mean ratio of 3D volume to 2D size was 130 (95% CI± 40).

The ratio of the CNV 3D volume to 2D size was significantly greater in subjects with reduced final visual acuity (VA), with ratio of 169±45 for patients with VA of 80 or less (ETDRS) compared with the ratio of 80±27 for subjects VA of above 80 ETDRS (p= 0.007). The authors will present 3D visualisations in relation to visual acuity.

Conclusions : CNVs are three-dimensional structures and 3D modeling gives a more accurate estimate of their true size than the 2D projection commonly used. The 3D/2D size ratio of CNVs was significantly larger in subjects with reduced final VA despite no evidence of activity on OCT. This may suggest that the true 3D size of a CNV has a predictive value in prognosis. This study was limited by a small sample size and larger studies are needed to determine how 3D rendered CNV size and morphology can aid the prognosis estimation in patients with wAMD.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.