Distribution and Prevalence of Refractive Error in Iranian Adult Population, A Cross- sectional Population-based Study (Results of the PERSIAN Eye Cohort Study(PECS))

Abstract

Abstract The PERSIAN Eye Cohort Study, a population-based cross-sectional study from 2015 to 2020, examined refractive error prevalence among 48618 Iranian adults aged 31 to 70. The study encompassed six centers in Iran, employing random cluster sampling for demographic, medical, and socioeconomic data collection through interviews. Ophthalmic exams included visual acuity, automated and manual objective refraction, subjective refraction, slit lamp, and fundus examinations. Using the spherical equivalent definition, the sample population was categorized into groups. Results indicated a mean age of 49.52 ± 9.31 and a mean refractive error of 0.26 diopters (D) ± 1.6 SD (95% CI: -0.27 to -0.24), ranging from − 26.1 to + 18.5 SD. Prevalence of myopia (<-0.5D) and hyperopia ( > + 0.5) was 22.6% (95% CI: 22.2–23%) and 12.5% (95% CI: 12.1–12.8%), respectively. Myopia significantly associated with female gender, older age, urban residency, higher education, higher income, and Fars ethnicity (p-value < 0.001 for all). Hyperopia significantly associated with female gender (p-value < 0.001), aging (p-value < 0.001), urban residency (p-value = 0.029), and lower income (p-value = 0.005). Astigmatism (> 1 D) was prevalent in 25.5% of participants (95% CI: 25.1–25.9%) and correlated with male gender, aging, urban residency, illiteracy, and higher income (p-value < 0.001, < 0.001, < 0.001, < 0.001, 0.014, respectively). The study's comparison with regional and international surveys highlighted the increase in myopia among those over 65 due to higher nuclear cataract rates in older adults. Myopia positively related to education, income, and urban residency, while hyperopia did not exhibit such associations.