Refractive error in central India: the Central India Eye and Medical Study

To evaluate the refractive error and its associations in the adult population of rural Central India.

Population-based study.

The Central India Eye and Medical Study is a population-based study performed in a markedly rural region in Central India. It included 4711 subjects (aged 30 years or older) of 5885 eligible subjects (response rate, 80.1%).

The participants underwent a detailed ophthalmic and medical examination, including standardized questions on the socioeconomic background, lifestyle, and social relations. This study was focused on the refractive error, the prevalence of hyperopia and myopia, and its factors.

Refractive error.

After exclusion of pseudophakic or aphakic eyes, 9076 (96.3%) eyes of 4619 (98.0%) subjects (2472 females) were included into the study. The mean refractive error was -0.20+/-1.51 diopters (D). Myopia of more than -0.50 D, -1.0 D, more than -6.0 D, and more than -8 D occurred in 17.0+/-0.6%, 13.0+/-0.5%, 0.9+/-1.4%, and 0.4+/-0.1% of the subjects, respectively. Hyperopia of more than 0.50 D was detected in 18.0+/-0.6% of the subjects. Refractive error was associated significantly (i.e., became more hyperopic) with lower age (P<0.001), lower best-corrected visual acuity (P<0.001), lower corneal refractive power (P<0.001), and shorter axial length (P<0.001). In multivariate analysis, refractive error was not significantly associated with the level of education (P = 0.56). High myopia (>-8 D) was associated significantly with male gender (P = 0.03) and lower best-corrected visual acuity (P<0.001). Mean anisometropia was 0.41+/-1.02 D. It was associated significantly with age (P<0.001), myopic refractive error (P<0.001), and lower best-corrected visual acuity (P<0.001). The mean astigmatic error was 0.29+/-0.60 D and was associated significantly with higher age (P<0.001), level of education (P = 0.01), lower best-corrected visual acuity (P<0.001), and higher corneal refractive power (P<0.001).

The rural population of Central India has not experienced a myopic shift as described for many urban populations at the Pacific Rim. Correspondingly, the relatively low level of education was not associated with myopia. Urbanization may be a major factor for myopization.

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