Pattern of myopia progression in Chinese medical students: a two-year follow-up study

To estimate myopia progression during a 2-year period in a cohort of medical students in mainland China. A 2-year longitudinal study was performed among 2,053 Chinese medical students (mean age 18.27 years, 1,057 females and 996 males) with their refraction measured at the start and the end of this study by autorefraction in cycloplegia. Information about the students' age, gender, home origin (urban or rural), and eye history was obtained through a questionnaire. The overall prevalence of myopia increased significantly from 78.5 % to 84.1 % (P < 0.001, right eye) and the mean refractive error increased significantly from -2.52 +/- 2.13 D to -2.84 +/- 2.16 D (P < 0.001, right eye) over the 2 years. The rural students had a significantly greater increase in prevalence of myopia and the refractive error towards myopia than the urban ones (P < 0.01 and 0.001 respectively). Females had a significantly faster myopic shift than males (P < 0.001). Participants with myopia initially showed the fastest myopic shift among the initial refractive groups. The relationship between the initial refractive error and the myopic shift remained significant after adjusting for sex and home origin (P < 0.05). Myopia progressed as increase in prevalence of myopia and change in refraction towards myopia in this study population. Participants who were more myopic at baseline were more likely to have myopia progression. Female and rural participants had a faster myopic shift compared to male and urban ones, respectively.