Elderly Chinese have lower myopia prevalence than Chinese youth, study finds

The high prevalence of myopia seen in young Chinese people may be due to environmental factors, a study in Taiwan suggests.

Elderly Chinese have a prevalence of myopia not much higher than white populations, the population-based study found, while younger Chinese have a much higher prevalence than younger whites. The difference suggests that changing environmental factors may account for the increased prevalence of myopia in younger Chinese, the authors theorized.

Ching-Yu Cheng and colleagues in Taipei, Taiwan, invited randomly selected residents of a district of Taipei who were at least 65 years old to undergo an ocular examination and answer a questionnaire. Of those invited, 1,361 participated in the exam, which included measurement of refractive error using autorefraction.

Prevalence rates were determined for myopia, high myopia, hyperopia, astigmatism and anisometropia. All refractive errors increased significantly as the participants grew older, except hyperopia, which tended to decrease with age.

Sex did not make a difference in the prevalence of any refractive error except hyperopia, in which women had a higher rate. Myopia was also weakly associated with a higher education level, the authors noted.

The severity of lens nuclear opacity was positively associated with rates of myopia and negatively associated with rates of hyperopia, they said.

The study is published in the November issue of Investigative Ophthalmology & Visual Science.