Comparing myopic progression of urban and rural Taiwanese schoolchildren.

PURPOSE: To compare myopic progression rates in Taiwanese schoolchildren between urban and rural areas. METHODS: Several longitudinal studies of myopic progression were performed in urban and rural areas. Five primary schools, four junior high schools, and two senior high schools were selected from both urban and rural areas. Ages ranged from 7 to 18 years. The refractive state of each student was measured with an autorefractometer under cycloplegia. RESULTS: Mean myopic progression in primary school children (ages 7 to 12) in the urban areas was around 0.20 D/year for boys and 0.27 D/year for girls. The mean myopic progression rate in urban children from primary to junior high school age (ages 10 to 15) was 0.43 D/year for boys and 0.50 D/year for girls, faster than that in rural children (0.24 and 0.31 D/year, respectively). The average progression rate was fastest in children in junior high school (ages 13 to 15), around 0.45 D/year in urban areas and 0.28 D/year in rural areas. In senior high schools (ages 16 to 18), myopic progression slowed to 0.17 D/ year in boys and 0.33 D/year in girls. Myopic progression in all groups was faster in myopic eyes than in emmetropic or hyperopic eyes. CONCLUSIONS: The average myopic progression in urban areas was greater than that in rural areas. Environmental factors such as urban development and academic grade level may be important contributing factors to myopic progression.

The prevalence of astigmatism in Taiwan schoolchildren.

PURPOSE: 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.