Epidemiology

Astigmatism has an estimated pooled prevalence of 14.9% (95% CI 12.7% to 17.1%) in children and 40.4% (95% CI 34.3% to 46.6%) in adults across all World Health Organization regions.[2]

Reported prevalence appears to vary by region (27% in northern and western Europe, 11% to 46% in the US, 31% to 58% in South Korea, 54% in Japan, 8% to 62% in China).[3] In the US, the condition probably affects about 1 in 3 people.[4]

The prevalence of astigmatism varies with age. There is a high prevalence (approximately 20%) in the first months of life when the curvature of the cornea is very steep.[5][6] As infants grow older, the cornea flattens and the prevalence of high degrees of astigmatism (>1 diopter) decreases, reaching a level of approximately 4.8% in preschool children.[7][8] Only a few young adults have an astigmatism >1 diopter, but around 63% of young adults ages 20-30 years exhibit ≥0.25 diopter of astigmatism.[9] With advancing age, the prevalence of astigmatism generally increases because of age-related changes in refractive index gradients within the crystalline lens.[3]

Astigmatism rates appear broadly comparable by sex.[3] Mild astigmatism predominates over moderate/significant astigmatism in both sexes, but severity correlates significantly with age; the prevalence of mild astigmatism increases until age 70 years, when the prevalence of moderate/significant astigmatism begins to increase.[3]

Several studies have reported increased risk for astigmatism among Hispanic, African-American, and Asian children.[10][11] Asian people have a relatively high prevalence of astigmatism, perhaps due to the greater tightness of the Asian eyelids and the narrower palpebral apertures.[2]​ One prospective cohort study indicated that 19.3% of Singaporean children had astigmatism with a cylinder power of ≥1 diopter.[12] In preschool Chinese children, a prevalence of 21.1% was found, and follow-up evaluation in a subset of these children showed that a significant percentage of children had stable and even increased astigmatism.[13] Native American people have an increased prevalence of high levels of astigmatism (>1 diopter), possibly due to hereditary and nutritional factors.

Astigmatism has been reported to be a prevalent refractive error in indigenous Brazilians, and other Brazilian populations.[14][15][16]

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