Abstract
PurposeTo investigate prevalence and risk factors for myopia, hyperopia and astigmatism in southern India.MethodsRandomly sampled villages were enumerated to identify people aged ≥40 years. Participants were interviewed for socioeconomic and lifestyle factors and attended a hospital‐based ophthalmic examination including visual acuity measurement and objective and subjective measurement of refractive status. Myopia was defined as spherical equivalent (SE) worse than −0.75 dioptres (D), hyperopia as SE ≥+1D and astigmatism as cylinder <−0.5.ResultsThe age‐standardised prevalences of myopia, hyperopia and astigmatism were 35.6% (95% CI: 34.7–36.6), 17.0% (95% CI: 16.3–17.8) and 32.6 (29.3–36.1), respectively. Of those with myopia (n = 1490), 70% had advanced cataract. Of these, 79% had presenting visual acuity (VA) less than 6/18 and after best correction, 44% of these improved to 6/12 or better and 27% remained with VA less than 6/18. In multivariable analyses (excluding patients with advanced cataract), increasing nuclear opacity score, current tobacco use, and increasing height were associated with higher odds of myopia. Higher levels of education were associated with increased odds of myopia in younger people and decreased odds in older people. Increasing time outdoors was associated with myopia only in older people. Increasing age and female gender were associated with hyperopia, and nuclear opacity score, increasing time outdoors, rural residence and current tobacco use with lower odds of hyperopia. After controlling for myopia, factors associated with higher odds of astigmatism were age, rural residence, and increasing nuclear opacity score and increasing education with lower odds.ConclusionsIn contrast to high‐income settings and in agreement with studies from low‐income settings, we found a rise in myopia with increasing age reflecting the high prevalence of advanced cataract.
Highlights
Myopia is the most common cause of refractive errors in both children and adults in many countries
The age-standardised prevalence was slightly higher in women (37.4%, 95% CI 36.1–38.6) than men (33.4%, 95% CI 32.1–34.6)
The prevalence of myopia in our study was similar to two recent populationbased studies in India using similar methods, the Chennai Glaucoma Study[21] and the Andhra Pradesh Eye Disease Study (APEDS),[9] respectively
Summary
Myopia is the most common cause of refractive errors in both children and adults in many countries. Comparisons of adult myopia prevalence across countries are complicated by variations in the age ranges of populations studied, definitions of myopia, prevalence of cataract and, within populations, ancestral heterogeneity, migration and. Prevalence and risk factors of refractive errors acculturation and secular trends in environmental risk factors.[1,2,3,4] For example, myopia prevalence in the United States differs by European, African and Hispanic ancestry,[5] and between Chinese, Malay and Indian ancestry in Singapore.[6] The pattern of age-specific rates of myopia differs between studies. Myopia prevalence has been observed to increase with age in studies in low-income settings[7,8,9] and to decrease with age in high-income settings,[5,10] while varied patterns, such U shape or inverted J shape distributions, have been reported in other settings, income and population subgroups.[11,12,13,14,15] Progress has been made in identifying genetic variants for myopia in populations of European or Asian ancestry (primarily Chinese).[16,17] Of the environmental risk factors, higher education, less time spent outdoors and more time spent in near work activities have been identified as risk factors for myopia primarily in studies from Western[18,19] and East and Southeast Asian populations[12,13,15,20] and have been suggested as a reason for the recent increase in the prevalence of myopia in young adults and children.[3,20]
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