Analysis of Choriocapillaris Flow Deficits Surrounding the “Dark-Halo” around Treatment-Naïve Choroidal Neovascularization Secondary to Age-Related Macular Degeneration

Abstract

Purpose : To evaluate the choriocapillaris (CC) flow deficits (FD) in the area around the “Dark-Halo” (DH) surrounding treatment-naïve choroidal neovascular membranes (CNVM) in eyes with age-related macular degeneration (AMD) compared to age-matched controls.

Methods : Spectral-domain optical-coherence tomography angiography (SD-OCTA) 6x6mm scans in eyes with treatment-naïve CNVM and normal controls were retrospectively reviewed from the Retina Clinics at the Stein and Doheny Eye Institutes, UCLA. The areas of CNVM and DH surrounding the neovascularization were manually detected by two independent masked graders. En-face CC angiograms were analyzed for percentage of flow deficits (FD%) in two concentric 500um-rings, ring 1 (R1) and ring 2 (R2), spanning a 1,000 um–wide region surrounding the DH around the CNVM, using the Phansalkar's local thresholding. Each treatment-naïve CNVM eye was age-matched with a normal control and the choriocapillaris was extracted from the same (location and size) concentric 500um-rings corresponding to the treatment-naïve CNVM eye. Mean CC FD% in R1 and R2 and mean difference between R1 and R2 were evaluated for each eye. A sub-analysis was carried out to investigate the differences in FD% in exudative versus non-exudative treatment-naïve CNVM, each of these sub-groups was also compared to the normal controls.

Results : Twenty-five eyes with treatment-naïve CNVM were enrolled and age-matched with normal controls. In R1, CC FD% measured 54.539±5.72 and 41.859±5.16 in the CNVM and normal control group, respectively (p<.05). In R2, we measured a mean CC FD% of 49.604±5.94 and 40.366±5.19 in the CNVM and normal control group, respectively (p<.05). The mean difference of CC FD% between the two rings was statistically signicantly greater in the AMD group compared to the control: 4.935±4.40 and 1.493±5.98, respectively (Table 1). A similar trend was observed when the exudative and non-exudative sub-groups were considered separately (Table 2).

Conclusions : In SD-OCTA images, the distribution of CC FD% in the area surrounding the DH around the CNVM varies with distance from the margin of the DH in both exudative and non-exudative sub-types. In particular, FD% tends to increase in the area closer to the DH. The relevance of the choriocapillaris to the pathophysiology of progression of CNVM warrants further study.

This is a 2020 ARVO Annual Meeting abstract.