Prevalence of age-related macular degeneration in the adult Chinese population in Hong Kong : Hong Kong eye study

Abstract

Age-related macular degeneration (AMD) is a well-known leading cause of vision loss worldwide. Previous epidemiological studies based on the Chinese residing in different geographic regions have shown inconsistent results regarding the prevalence of AMD and the severity of AMD lesions. Results from the studies conducted in mainland China, showed relatively lower compared with the results from the studies based on ethnic Chinese in Taiwan, the U.S. and Singapore. To my knowledge, there are few data available currently on the epidemiology of AMD in Hong Kong. It is important to focus on the Chinese due to its large ageing population and the public health impact induced by its increasing emigrations globally. The investigation of AMD in Hong Kong will be beneficial for the comprehensive understanding of AMD in Chinese ethnicity.

The present study is to 1) determine the age- and sex-specific prevalence and associated risk factors of early and late AMD in an adult Chinese population in Hong Kong; 2) give a comprehensive description of AMD lesions including the size, type, numbers, distribution and confluence of drusen and pigmentary abnormalities; 3) provide a comparison of the prevalence and risk factors in this Chinese population of Hong Kong with that in Chinese people residing in different geographic regions including mainland China, Taiwan, Singapore and the U.S.

The Hong Kong Eye Study was a population-based, cross-sectional study of ethnic Chinese adults aged 18-92 years residing in Hong Kong. 2018 adult local residents were recruited in the study between 2016-2017. 1401 participants age 40 years and older were included in the evaluation of drusen and pigmentation abnormalities using a modified Wisconsin Age-Related Maculopathy Grading System. After proper dilatation of the pupils, participants were given wide-angle fundus photography.

The mean age of the participants was 58.82 ± 10.9 years. The prevalence of early AMD was 7.0% (95% confidence interval [CI], 5.7–8.3); of soft distinct drusen, 9.1% (95% CI, 7.6-10.6); and of any pigmentary abnormalities, 6.6% (95% CI, 5.3–7.9). The prevalence of late AMD was 0.8% (95% CI, 0.3–1.2). Among 11 participants who had late AMD, 3 of them were geographic atrophy, and 8 of them were neovascular AMD. Risk factors for early AMD were older age (odds ratio [OR], 1.62; 95% CI, 1.16-1.82) and axial length (OR, 0.74; 95% CI, 0.61-0.93). Risk factors for late AMD were older age (OR, 1.69; 95% CI, 1.25-1.90) and hsCRP (OR, 1.45; 95% CI, 0.82-2.87).

In this Chinese population, we found the prevalence of early AMD, late AMD, and soft drusen were relatively higher than the Chinese population in Beijing based on the previous study conducted in mainland China. However, comparable prevalence rates were observed compared with the Chinese people residing in Taiwan, Singapore and the U.S.