The prevalence of astigmatism in Taiwan schoolchildren.
OBJECTIVE
To understand the prevalence and distribution of astigmatism in schoolchildren in Taiwan, we analyzed and compared the nationwide survey data in 1995 and 2000.


METHODS
A total of 11,175 students were enrolled in 1995, and 10,878 students were enrolled in 2000. The refractive status of each student was measured with an autorefractor during cycloplegia and rechecked with retinoscopy.


RESULTS
About half of schoolchildren (57.5% in 1995 and 49.0% in 2000) had no astigmatism (<0.5 D). About one third of schoolchildren's astigmatism was <1 D (27.9% vs. 32.6%). Eleven percent of schoolchildren in 1995 and 13% in 2000 had astigmatism between 1.0 and 2.0 D. Less than 2% of students had astigmatism >3.0 D (1.3% in 1995 and 1.8% in 2000). Most astigmatism was with-the-rule: 83.3% in 1995 and 89.9% in 2000. Only 16.6% of children in 1995 and 9.7% in 2000 had against-the-rule astigmatism. Very little astigmatism was oblique (0.1% in 1995 and 0.4% in 2000). The rate of myopic astigmatism increased with age. In contrast, the rate of hyperopic and mixed astigmatism decreased with age. In addition, the rate of with-the-rule astigmatism increased and the rate of against-the-rule decreased with respect to age, but oblique astigmatism was rather stable with age.


CONCLUSIONS
Most schoolchildren had little or no astigmatism. In Taiwan, most astigmatism is <1 D and is myopic with-the-rule astigmatism. There was more myopic astigmatism and with-the-rule astigmatism in 2000 than in 1995.
Shih
Yung-Feng
YF
Department of Ophthalmology, College ofMedicine, National Taiwan University, Taipei, Taiwan.
Hsiao
C Kate
CK
Tung
Yi-Liang
YL
Lin
Luke L K
LL
Chen
Chien-Jen
CJ
Hung
Por-Tying
PT
D000293:Adolescent; D000375:Aging; D001251:Astigmatism / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D002648:Child; D006801:Humans; D006956:Hyperopia / Q000150:complications; D009216:Myopia / Q000150:complications; D015995:Prevalence; D012029:Refraction, Ocular; D013334:Students / Q000706:statistics & numerical data*; D013624:Taiwan / Q000453:epidemiology