Incidence and progression of astigmatism in Singaporean children

Abstract

PURPOSE. This study investigated the incidence and progression, as well as factors associated with changes in astigmatism in school children. METHODS. This was a prospective cohort study. Children 7 to 9 years of age, of Chinese, Malay, and Asian Indian ethnicity, were examined annually over a 4-year period. Cycloplegic autorefraction was performed. A questionnaire was used to evaluate risk factors for incidence and progression of astigmatism. RESULTS. The cumulative 3-year incidence rate of astigmatism was 33.6% (cylinder power of 0.5 D or worse) or 11.5% (cylinder power of 1.0 D or worse). Myopic children had a higher incidence rate of astigmatism than nonmyopes (P < 0.001). The mean J0 change per year was 0.012 D (95% CI: 0.007-0.018), whereas J45 did not show a significant change each year (mean, 0.001 D per year). Chinese children had greater worsening of J0 per year (P < 0.001). Girls also had significantly greater progression of J0 than did boys (P < 0.001). Similarly, myopia at baseline (P < 0.001) and the hours of computer use (P = 0.049) were associated with a greater progression rate of J0. J0 tended to improve in children with compound hyperopic astigmatism, worsen in children with compound myopic astigmatism, and remain stable in mixed astigmatics. CONCLUSIONS. Although there was minimal progression of astigmatism in school age children (0.44-0.53 D) over this period of follow-up, incident cases of astigmatism (> 1.0 D) were not uncommon. The progression rate of astigmatism was affected by the ethnicity, presence of myopia, axis, and subtype of astigmatism.