Incidence and its risk factors of high myopia in Chinese rural adults: A population-based six-year cohort study

Abstract

Background To investigate the incidence rate of high myopia and its risk factors in adults. Methods This was a population-based cohort study, 4582 adults aged ≥ 30 years from rural area of China were included. The follow-up duration was six years. Objective refraction (sphere, cylinder, and axis) was measured using an autorefractor. Multivariable Logistic regression was used to explore risk factors of high myopia, odds ratio (OR) with 95% confidence interval (CI) were reported. Results During the six-year follow-up, 25 participants developed high myopia. The incidence rate was 0.55% (95%CI: 0.44% to 0.66%), and were 0.54% (11/2035) in males and 0.55% (14/2547) in females. The age-gender standardized annual incidence rate was 0.11%. The median changes in spherical equivalent (SE) of all participants was 0.25D (IQR: −0.125 to 0.625). For the baseline myopic adults and non-myopic adults, the median changes in SE were 0.125D (IQR: −0.375 to 0.5), and 0.25D (IQR: −0.125 to 0.625). The difference was significant (p < 0.001). Of the two subgroups, 1.52% (21/1383) and 0.13% (4/3199) developed high myopia during six years. The risk of developing high myopia in baseline myopic adults was 11.7 times higher than that of the baseline non-myopic adults ( p < 0.001). Age (OR = 1.061, 95%CI: 1.022 to 1.103, p = 0.002), and baseline myopia (OR = 1.007, 95%CI: 1.001 to 1.012, p < 0.001) were risk factors for high myopia. Conclusion The age-gender standardized annual incidence rate of high myopia in Chinese rural adults is 0.11%. More than 30% of adults still have myopia progression. Myopia control is of great significance for high myopia prevention.