4 , 6 , 25 , 31 Although some studies found no significant changes in the prevalence of astigmatism in this age group, 4 the majority of the studies have reporetd a decreasing trend for stigmatism from the neonatal period to adolescence followed by an increasing trend in middle ages. 33 , 38 However, the results of this study were slightly different from other studies, 4 , 6 , 25 , 31 , 33 which could be due to genetic and environmental factors.
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