Refractive errors and visual impairment among children and adolescents in southernmost China.

BACKGROUND: Refractive errors and visual impairment in southernmost China have not been reported previously. We aim to investigate and determine the age-specific prevalence of myopia, hyperopia, astigmatism, and visual impairment based on a large population cross-sectional study in Hainan area of southernmost tropical province in China. METHODS: A population-based sample of 31,524 children aged 6-15 years from Hainan was assessed. Non-cycloplegic autorefraction and visual acuity (VA) analyses were performed on all participants and a subgroup of participants undergoing cycloplegia. RESULTS: Of all participants, 23.0% presented uncorrected VA (UCVA) was worse than 20/40 in worse eye, 6.0% presented mild presenting visual acuity impairment (PVAI), 7.0% presented moderate PVAI, 0.2% presented severe PVAI in the better eye, and 46.9% presented abnormal UCVA [worse than 20/25 (≥ 6, < 8 years old) and worse than 20/20 (≥ 8 years and older)] at least in one eye. The overall prevalence of myopia [spherical equivalent (SE) ≤ - 0.50 D] and high myopia (SE ≤ - 6.00 D) were 46.0%, 1.0% respectively. Hyperopia [SE ≥ + 1.00 D (≥ 7 years old) and SE ≥ + 2.00 D (≥ 6, < 7 years old)] and significant hyperopia (SE ≥ + 3.00 D) were 4.2 and 0.6%, respectively. Astigmatism [cylinder ≥ 1.00 D (≥ 7 years old) and ≥ 1.75 D (≥ 6, < 7 years old)] was found in 31.9%. CONCLUSIONS: Myopia was the most common refractive error in southernmost province in China (Hainan). Its prevalence increased with age, while hyperopia prevalence showed a decreasing trend. However, myopia, especially high myopia prevalence was much lower than in other urban regions across China.