Abstract
Purpose To assess the changing profile of astigmatism in Chinese schoolchildren and the association between astigmatism changes and ocular biometry. Methods We examined and followed up 1,463 children aged 6–9 years from Wenzhou, China. We measured noncycloplegic refraction twice each year and tested axial length (AL) and corneal radius of curvature (CRC) annually for two years. We defined clinically significant astigmatism (CSA) as ≤−0.75 diopter (D) and non-CSA astigmatism as ≤0 to >−0.75 D. Results Prevalence of CSA at baseline was 22.4% (n = 327) and decreased to 20.3% (n = 297) at the two-year follow-up (P = 0.046). Ninety-two (8.1%) non-CSA children developed CSA. In multiple regression, after adjusting for age, gender, baseline cylinder refraction, and axis, children who had longer baseline ALs (>23.58 mm; odds ratio (OR) = 5.19, 95% confidence interval (CI): 2.72–9.90) and longer baseline AL/CRC ratio (>2.99, OR = 4.99, 95% CI: 2.37–10.51) were more likely to develop CSA after two years. Four-hundred and two (27.5%) children had increased astigmatism, 783 (53.5%) had decreased, and 278 (19.0%) had no change during the two-year follow-up. Children with increased astigmatism had longer baseline ALs (23.33 mm, P < 0.001), higher AL/CRC ratios (2.99 mm, P < 0.001), and more negative spherical equivalent refraction (SER) (−0.63 D, P < 0.001) compared with the decreased and no astigmatism change subgroups. Also, children in the increased astigmatism subgroup had more AL growth (0.68 mm, P < 0.001), higher increases in AL/CRC ratio (0.08, P < 0.001), and more negative SER change (−0.86 D, P < 0.001) compared with the decreased and no astigmatism change subgroups. Conclusions The prevalence of astigmatism decreased slightly over the two-year study period. Longer ALs and higher AL/CRC ratios were independent risk factors for developing CSA. Increased astigmatism was associated with AL growth, AL/CRC ratio increases, and the development of myopia. This trial is registered with ChiCTR1800019915.
Highlights
Astigmatism is a frequent, correctable cause of visual impairment in children, whether or not this coexists with myopia or hyperopia [1]
Using the least significant difference (LSD) pairwise comparison methods (Table 5), we found that the subgroup of children with increased clinically significant astigmatism (CSA) had longer axial length (AL) (23.33 mm), larger AL/corneal radius of curvature (CRC) ratios (2.99), and more myopic spherical equivalent refraction (SER) (−0.63 D) compared with children who had decreases in these biometric parameters (AL 22.89 mm, AL/CRC ratio 2.94, SER −0.07 D, P < 0.001 for each)
Prevalence of Astigmatism. e prevalence of astigmatism varies according to ethnicity, population, and measurement standards
Summary
Astigmatism is a frequent, correctable cause of visual impairment in children, whether or not this coexists with myopia or hyperopia [1]. We know that the high prevalence of astigmatism at birth decreases throughout infancy [2], but its change with age is less certain. In Taiwan, Chan et al [4] found that Chinese primary schoolchildren showed a decrease in astigmatism at the one-year follow-up. In European children (Parssinen et al [5]) and native American populations (Twelker et al [6]), the presence of astigmatism predisposes development of progressive myopia. In Twelker’s et al.’s [6] study of native American population, Dobson et al [7] found rates of myopia progression in astigmatic and nonastigmatic preschool children over a 4- to 8-year follow-up to be similar. Parssinen [8] observed that myopia progression appeared unrelated to the Journal of Ophthalmology initial astigmatism. Parssinen [8] observed that myopia progression appeared unrelated to the Journal of Ophthalmology initial astigmatism. us, the association between astigmatism and myopia is controversial [9]
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