To assess the prevalence of refractive errors and vision impairment in school-age
children in Shunyi District, northeast of Beijing, the Peoples Republic of China.
Random selection of village-based clusters was used to identify a sample of children
5 to 15 years of age. Resident registration books were used to enumerate eligible
children in the selected villages and identify their current school. Ophthalmic examinations
were conducted in 132 schools on children from 29 clusters during May 1988 to July
1998, including visual acuity measurements, cycloplegic retinoscopy, cycloplegic autorefraction,
ocular motility evaluation, and examination of the external eye, anterior segment,
media, and fundus. Independent replicate measurements of all children with reduced
vision and a sample of those with normal vision were done for quality assurance monitoring
in three schools.
A total of 6,134 children from 4,338 households were enumerated, and 5,884 children
(95.9%) were examined. The prevalence of uncorrected, presenting, and best visual
acuity 0.5 (20/40) or worse in at least one eye was 12.8%, 10.9%, and 1.8%, respectively;
0.4% had best visual acuity 0.5 or worse in both eyes. Refractive error was the cause
in 89.5% of the 1,236 eyes with reduced vision, amblyopia in 5%, other causes in 1.5%,
with unexplained causes in the remaining 4%. Myopia -0.5 diopter or less in either
eye was essentially absent in 5-year-old children, but increased to 36.7% in males
and 55.0% in females by age 15. Over this same age range, hyperopia 2 diopters or
greater decreased from 8.8% in males and 19.6% in females to less than 2% in both.
Females had a significantly higher risk of both myopia and hyperopia.
Reduced vision because of myopia is an important public health problem in school-age
children in Shunyi District. More than 9% of children could benefit from prescription
glasses. Further studies are needed to determine whether the upward trend in the prevalence
of myopia continues far beyond age 15 and whether the development of myopia is changing
for more recent birth cohorts.