PURPOSE. To determine the prevalence, incidence, and progression of myopia of Chinese children in Hong Kong. METHODS. A cross-sectional survey was initially conducted. A longitudinal follow-up study was then conducted 12 months later. RESULTS. A total of 7560 children of mean age 9.33 (95% confidence interval [CI] ϭ 9.11-9.45; range, 5-16) participated in the study. Mean spherical equivalent refraction (SER) was Ϫ0.33 D (SD ϭ 11.56; range, Ϫ13.13 to ϩ14.25 D). Myopia (SER Յ Ϫ0.50 D) was the most common refractive error and was found in 36.71% Ϯ 2.87% (SD) of children. Prevalence of myopia correlated positively with older age. Children aged 11 years were almost 15 times more likely to have myopia than were children younger than 7 years (Odds ratio [OR] ϭ 14.81; 95% CI ϭ 14.17-15.48). Incidence of myopia was 144.1 Ϯ 2.31 (SD) per 1000 primary school children per annum. Increasing age was correlated with increased incidence of myopia, with highest risk in children ages 11 years (OR ϭ 2.27; 95% CI ϭ 2.11-2.44). The average annual change in SER for children with myopia (SER Յ Ϫ0.50 D) was Ϫ0.63 D (SD ϭ 3.44) compared with Ϫ0.29 D (SD ϭ 2.96) for those who were not myopic at the beginning of the study (P Ͻ 0.001). CONCLUSIONS. The results show that the prevalence and progression of myopia in Hong Kong children was much higher than those previously reported in Western countries. The longterm socioeconomic impact of these findings warrants further studies. (Invest Ophthalmol Vis Sci
