Prevalence and Patterns of Myopic Progression Among Schoolchildren: Eight-Year Longitudinal Study
The patterns of myopic progression and the degree of myopia were studied after an 8-year follow-up of schoolchildren. A longitudinal study was conducted in Taiwan from 1984 to 1991, with 593 children originally enrolled. Altogether 278 children were followed completely from the ages of 7 to 15 years. The cycloplegic refraction, corneal radius, and biometric axial length were measured each year. The results showed that the mean myopic shift was -0.11 D per year before myopia, whereas there was -0.64 D per year myopic progression after myopia development. During emmetropization 73% of subjects had a myopic shift of less than -0.25 D per year; in 50% of myopic students the myopic progression was -0.5 to -1.0 D per year and in 19% more than -1.0 D per year. Analyzing the patterns of myopic shift, we found that the rate of myopic shift was more rapid while myopization occurred. The pattern of myopic progression remains the same for myopic children with different age of onset. Axial elongation of the eyeball is the main ocular component that changes during myopic progression.