Investigation on the prevalence and influencing factors of myopia among children and adolescents in Liyang city

Objective: To investigate the prevalence of myopia among children and adolescents in a local area (Liyang City) of China and analyze the influencing factors, so as to formulate corresponding preventive measures. Methods: A questionnaire survey was conducted, mainly investigating subjects' age, gender, residence (urban/rural areas), parental myopia, daily time spent outdoors, daily sleep time, distance between computer screen and eyes, less than one punch (10 cm) from the chest to the edge of the desk when reading and writing, one inch (3 cm) between finger and pen tip when writing, number of in-school physical education (PE) classes, length of TV watching, and size of TV. The myopia of all participants was recorded. Results: This study enrolled 7,948 children and adolescents, including 4,733 (59.55%) cases of myopia, 1,025 (12.90%) of astigmatism, 251 (3.16%) of hyperopia, and 699 (8.79%) of anisometropia respectively. There were 2,519 (53.22%) cases of myopia in the left eye and 2,214 (46.78%) in the right eye. Low, moderate, and high myopia were determined in 2,682 (56.67%), 1,583 (33.45%), and 468 (9.89%), respectively. In terms of spherical equivalent (SEQ), a statistically lower SEQ was observed in urban areas (-1.56 +/- 0.46 d) versus suburban counties (-1.17 +/- 0.33 d), and in females (-1.68 +/- 0.30 d) compared with males (-1.17 +/- 0.44 d). The mean SEQ gradually decreased with age. The prevalence of myopia was 63.84% (2,436/3,816) in females, statistically higher than that of 55.59% (2,197/4,132) in males (chi(2)=56.00, P < 0.0001). The incidence of myopia was statistically higher in urban areas (67.93% [3,321/4,889]) versus rural areas (46.16% [1,412/3,059]). Parental myopia, one inch between finger and pen tip when writing, daily time spent outdoors, daily sleep time, distance between computer screen and eyes, less than one punch from the chest to the edge of the desk when reading and writing, number of in-school PE classes, and daily length of TV watching were significantly correlated with the occurrence of myopia. Conclusions: Parents are advised to pay attention to daily time spent outdoors, sleep time, distance between the computer screen and the eyes, distance between the chest and the edge of the table when reading and writing, and length of TV watching of their children. As far as schools are concerned, PE activity time should be properly maintained to ensure that children have enough outdoor exercise time to reduce eye fatigue.