The prevalence of refractive error and visual impairment caused by uncorrected refractive error in China

Abstract

Purpose: WHO reports 46% of world vision impairment from refractive error (RE)

among children occurs in China. We estimated RE prevalence and associated vision

impairment (VI) among Chinese children and adults.

Methods: Data from population-based studies were stratified by gender in age intervals

of 3 years (ages 3-17 y) or 10 years (ages >= 30 y): counts of persons with myopia

(worse eye spherical equivalent <= -1.0D, <= -2.0D, <= -6.0D) and prevalence of low

vision (< 6/12 in the better-seeing eye for children and < 6/18 for adults) and blindness

(<=6/60) attributable to RE. Figures for VI included persons with habitual vision below

the cutoff improving to above the cutoff with refraction, and those with myopic

retinopathy. Estimates for ages 18-29 y were obtained from regression models derived

from the pooled estimates. Prevalence of myopia and VI attributable to RE in each

age/gender category was calculated by applying modeled rates to 2000 China census

figures and projections for 2020. Association with VI attributable to RE was tested for:

gender, urban versus rural residence, and residence in provinces with per capita GDP in

the upper versus lower 50% for China.

Results: Data were obtained from 5 cohorts for children and 14 for adults. There were

291 million and 21.4 million persons with myopia <= -1.0D and <= -6.0D respectively in

2000, expected to rise to 306 million and 36.9 million by 2020. Of these, 18.4 million

were blind and 116 million had low vision in 2000, with figures of 25.3 million and 123

million in 2020. Children accounted for the following proportion of RE disease burden in

China in 2000: myopia <= -1.0D: 19.0%; RE-associated low vision: 56.1%; blindness:

14.1%. Refractive error was responsible for 82.3% of blindness and 90.5% of low vision

among children, and 11.6% and 64.4% of blindness and low vision among adults. Urban

residence (OR 1.85, P = 0.004) and higher GDP (OR 10.6, P < 0.001) were associated

with refractive blindness among children. For adults, lower GDP was associated with

refractive blindness (OR 1.47, P = 0.01). Gender was un-associated with refractive

blindness among children or adults.

Conclusions: Both children and adults suffer a heavy burden of VI associated with RE in

China. Income may affect risk for such VI differently among children and adults.