Prevalence and causes of amblyopia in a rural adult population of Chinese: The Handan Eye Study

Abstract

Objective: To determine the prevalence of and factors associated with amblyopia in a rural Chinese population. Design: Population-based, cross-sectional study. Participants: Six thousand eight hundred thirty Han Chinese aged 30 years or more, recruited from Yongnian County, Handan, Hebei Province, China. Methods: Thirteen villages in the Yongnian County of Handan were selected randomly, and residents of these selected villages 30 years of age or older were invited to participate in the Handan Eye Study. Participants underwent a comprehensive eye examination, including standardized visual acuity (VA) tests using logarithm of the minimum angle of resolution charts. Prevalence rates were age- and gender-standardized to the 2000 China census. Main Outcome Measures: The proportion of rural Chinese population aged 30 years or older with amblyopia. Unilateral amblyopia was diagnosed if best-corrected VA (BCVA) was 20/32 or worse in the amblyopic eye and was not attributable directly to any underlying structural abnormality of the eye or visual pathway. Bilateral amblyopia was diagnosed if BCVA was 20/32 or less in both eyes and if there was a history of form deprivation during the sensitive period of visual development, such as media opacities or high, uncorrected ametropia. Results: Amblyopia was diagnosed in 205 participants, with an age- and gender-adjusted prevalence of 2.8%. Of these, 1.7% were unilateral cases and 1.1% were bilateral cases. Underlying causes included anisometropia (67.3%), strabismus (5.4%), mixed strabismus and anisometropia (4.4%), visual deprivation (9.8%), astigmatism association (9.8%), and other (3.4%). Of the amblyopia cases, 47.6% were hypermetropic. Conclusions: In this rural Chinese population, 2.8% of adults 30 to 80 years of age had amblyopia, a prevalence rate broadly consistent with that of most other studies. One third of the cases were bilateral, and anisometropia was the most common cause of this condition. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. © 2011 American Academy of Ophthalmology.