Prevalence and Causes of Visual Impairment and Blindness among Adult Chinese in Hong Kong – The Hong Kong Eye Study

ABSTRACT

Purpose

To investigate the prevalence, associations, and causes of visual impairment and blindness in the adult population of Hong Kong.

Methods

This cross-sectional population-based study included 2018 (870, 43% male) randomly selected adults with a mean age 52 ± 16 years (range 18–90 years) in Hong Kong. Each participant underwent comprehensive ophthalmic examinations. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) of each eye was recorded. Prevalence of visual impairment and blindness was calculated using both World Health Organization (WHO) and United States (US) definitions, based on BCVA and PVA.

Results

Visual acuity measurements were available for 1952 (96.8%) participants. The prevalence of visual impairment, based on BCVA value, using WHO and US definition, was 1.0 ± 0.1% and 2.7 ± 0.4%, respectively. The prevalence of visual impairment, based on PVA value, was 5.1 ± 0.5% and 14.0 ± 0.8%, using WHO and US definition, respectively. Multivariate analysis demonstrated the presence of visual impairment (PVA, WHO definition) increased significantly with older age (odds ratio 1.039, P < .001) and thinner central cornea thickness (odds ratio 0.994, P = .014), but not significantly associated with other socioeconomic, systemic or ocular parameters after adjusting for age and central corneal thickness. Under-correction of refractive error was the most common reason for presenting visual impairment. Causes of impaired BCVA were cataract (37%), age-related macular degeneration (26%), diabetic macular edema (11%), glaucoma (11%), epiretinal membrane (5%), and unknown (11%).

Conclusion

The prevalence of visual impairment in Hong Kong increased significantly with older age and thinner central corneal thickness. The major causes for impairment were under-correction of refractive error, cataract, and age-related macular degeneration.

KEYWORDS:

• Hong Kong
• prevalence
• eye diseases
• visual impairment
• cataract

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the writing and content of this article.

Additional information

Funding

The present study is part of the ‘Chloe Ho Safeguarding Vision Initiative’ and was funded by the Jessie & George Ho Charitable Foundation. It was also funded by the Hong Kong Jockey Club Charities Trust, which funded the establishment of the FAMILY cohort from 2007 to 2014. The funding organization had no role in the design or conduct of this research.