Racial differences in choroidal neovacularisation due to age–related macular degeneration

Abstract

Abstract: : Purpose: There is limited published data on angiographic characteristics of choroidal neovascularisation (CNV) in age–related macular degeneration (AMD) in different racial groups. In this study, we compared the angiographic characteristics of CNV due to AMD in two racial groups: Caucasians and Chinese. Methods:Consecutive colour and fluorescein angiogram images were examined from three centres: King’s College Hospital, London (KCH), West Kent Eye Centre, England (WKEC) and Prince of Wales University Hospital, Hong Kong (HK). Inclusion criteria: CNV due to AMD in patients above the age of 50. Only Caucasians were included from the two UK centres and only Chinese were included from the centre in Hong Kong. Exclusion criteria: CNV secondary to non–AMD causes such as myopia and all cases of polypoidal choroidal vasculopathy (PCV) were excluded. All tertiary referrals were also excluded. The images for each patient were stored in separate folders. Two graders assessed the images in each folder independently. Discrepancies in grading were adjudicated by the senior author. CNV were classified into 3 sub–groups based on the TAP study protocol: 1. Predominantly classic CNV where the area of classic CNV > 50% of the area of the entire lesion. 2. Minimally classic CNV where the area of the classic CNV < 50% and > 0% of the entire lesion. 3.Pure occult CNV where there is no classic component. The frequency of each type of CNV was compared between the ethnic groups using Fisher’s exact test. Results: 

There was no statistically significant difference in the angiographic classification of CNVs in the two Caucasian cohorts (p > 0.1). In contrast, the Chinese cohort had statistically significant less proportion of predominantly classic CNV (p < 0.005) and higher proportion of occult CNV (p < 0.005) compared to the Caucasian groups. Conclusion:There are considerable racial differences in the characteristics of CNV between the Caucasian and Chinese population. It is uncertain whether this is due to genetic or environmental differences.

Keywords: age–related macular degeneration • choroid: neovascularization • clinical (human) or epidemiologic studies: natural history