Outcomes
diopter
MYOPIA, LUNG, MYOPIA, CYCLOPLEGIA
All outcomes were measured at baseline and the end of 1 academic year. The primary outcome was the between-group mean difference in mathematics test scores after 1 academic year. Mathematics tests were administered at school on the same day. Unified test papers were designed with professional assistance from the Education Bureau of Yudu in accordance with the design principles of the International Mathematics and Science StudySecondary outcomes were overall physical fitness score and myopia incidence after 1 academic year. Physical fitness scores were assessed at school by trained examiners from Zhongshan Ophthalmic Center, with reference to the 2018 National Physical Fitness Survey Monitoring Programme in China. Height and weight were measured using a height and weight scale and with children standing in light clothing and without shoes. Body mass index was calculated as weight in kilograms divided by height in meters squared. Lung vital capacity was measured by a spirometer. Fifty-meter sprint, sit-and-reach test, 1-minute sit-up, and 1-minute jump rope were conducted. The overall physical fitness score was calculated as the sum of weighted individual scores, with age- and sex-stratified weights of body mass index at 15%, lung vital capacity at 15%, 50-m sprint at 20%, sit-and-reach test at 20%, 1-minute sit-up at 10%, and 1-minute jump rope at 20%. These weights were derived from the Chinese National Student Physical Fitness Standard, a norm testing battery in China.Ocular examinations were performed at school by ophthalmologists and optometrists from Zhongshan Ophthalmic Center. Axial length was measured using an optical biometer (IOLMaster; Carl Zeiss Meditec), and measurements were repeated 5 times for each eye. Cycloplegia was achieved with 3 drops of 1% cyclopentolate administered at 0, 5, and 20 minutes. Cycloplegia was considered to be complete if the pupillary light reflex was absent and the pupil was dilated to at least 6 mm. Cycloplegic autorefraction (KR 8800; Topcon) was performed and repeated 3 times for each eye. Spherical equivalent refraction (SER) was calculated as the spherical power plus half cylindrical power. Myopia was defined as a cycloplegic SER of −0.5 D (diopter) or less in either eye.