The Association between Childhood Myopia Prevalence and Environmental Factors in China: A Metaregression Analysis

Table 2

Relationship between covariates and myopia prevalence from univariate metaregression analyses in all the studies (5–20 years), studies involving only primary schoolchildren (5–14 years), and only secondary schoolchildren (12–20 years).

Covariates	All studies (n = 49)	Primary schoolchildren (n = 37)	Secondary schoolchildren (n = 19)
	R^2	R^2	R^2
Annual sunshine hours	27.97	58.32	28.74
Annual temperature	24.66	49.70	18.12
Population density	7.06	8.94	0.287
Seasonal difference in sunshine hours	1.54	12.54	2.21
Year of publication	4.04	8.26	1.93

R²: coefficient of determination. The values highlighted in bold indicate a significant association.