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Study shows escalating incidence of myopia in Chinese children
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A study involving a large cohort of Chinese schoolchildren 7 to 15 years old showed escalating incidence of myopia and high myopia, starting in the early years of primary school.
The study examined two cohorts of students in 19 primary and 22 junior high schools of Guangzhou, China. The two cohorts were followed up until completion of the school cycles, respectively for 5 and 2 years, beginning in 2010.
The annual incidence of myopia was defined as the proportion of children with myopia who did not have myopia in the previous year, and the same criteria were adopted for high myopia (spherical equivalent refraction 6.0 D or less).
A total of 4,741 students were included. Baseline prevalence of myopia was 12% in grade 1 students and 67.4% in grade 7 students. In both cohorts, prevalence increased rapidly and consistently, with an incidence of 20% to 30% each year. At the end of primary school, 69.9% of children were myopic, and at the end of junior high school, 79.4% of students were myopic.
The incidence of high myopia was initially less than 1% in the primary school cohort but increased to more than 2% in the junior high school cohort. By completion of junior high school, 7% of the students had high myopia.
Progression of myopia was observed as early as between grade 1 and 2, during which 19% of children developed myopia. The highest incidence rate was between grade 5 and 6, during which 30% of children became myopic. The probability of nonmyopic children remaining nonmyopic throughout primary school was 28.9%, and for nonmyopic junior high school students who were nonmyopic at grade 7, the probability of remaining nonmyopic until grade 9 was 54%.
“In conclusion, the data presented here update our perspective on the rapid escalation of myopia in China with implications for eye care professionals and health administrators,” the authors wrote.
Whether this escalation is due to genetic predisposition or lifestyle it is still unclear. However, the early onset of myopia found in this study suggests that “interventions intent on preventing the development of myopia in Chinese children might aim to take place by the start of primary school,” they concluded. – by Michela Cimberle
Disclosures: The authors reported no relevant financial disclosure.
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