Choroidal vascular changes in age-related macular degeneration

Abstract

Purpose: To assess the choroidal vascular changes using choroidal vascularity index (CVI) in patients with age-related macular degeneration (AMD) compared to controls.

Methods: Enhanced depth imaging (EDI) optical coherence tomography (OCT) scans of 64 patients with unilateral or bilateral AMD were obtained. Images with a poorly demarcated choroidal-scleral interface (CSI) were excluded from the analysis. Foveal scans of 63 AMD eyes and 35 'normal fellow' eyes were analysed. Images of 30 eyes from 18 age-matched healthy subjects were included as controls. Choroidal vascularity index (CVI) was derived from binarization of EDI OCT images, using fiji software.

Results: The mean age was 56.50 ± 5.50 years for AMD patients and 52.25 ± 6.75 years for controls. All patients were treatment naïve. Subfoveal choroidal thickness (SFCT) in AMD, 'normal fellow' eyes and controls was 314.02 ± 78.80 μm, 300.88 ± 53.85 μm and 278.5 ± 65.31 μm, respectively. Choroidal vascularity index (CVI) in AMD, 'normal fellow' eyes and controls was 64.04 ± 2.43%, 64.66 ± 2.25% and 66.07 ± 1.72%, respectively. Choroidal vascularity index (CVI) of both AMD and 'normal fellow' eyes was significantly lower compared to controls (p < 0.0001 and p = 0.007). The SFCT of AMD eye was not found to be significantly different from 'normal fellow eyes' (p = 0.45).

Conclusion: There was no statistical difference in SFCT, but CVI was significantly lower in patients with AMD. Choroidal vascularity index (CVI) was also lower in 'normal fellow' AMD eyes as compared to controls. This suggests possible reduction in choroidal vascularity in eyes with AMD and also to a certain extent in the 'normal fellow' eyes without phenotypical manifestations and may suggest underlying choroidal morphological change leading to wet AMD.

Keywords: age-related macular degeneration; choroidal vascularity index; enhanced depth imaging OCT; image binarization; optical coherence tomography; subfoveal choroidal thickness.