Near work, outdoor activity, and myopia in children in rural China: the Handan offspring myopia study

BMC Ophthalmology

Table 4 Mean spherical equivalent (diopter)^a as a function of outdoor activity (tertiles of hours per day)

Outdoor activity (hours per day)^b	Low (0~2.3) N = 191	Moderate (2.3~3.2) N = 187	High (>3.2) N = 194	P value
Gender
Boys	0.05	0.10	0.27	0.32
Girls	−0.13	−0.30	−0.10	0.49
Refractive Status
Myopia	−1.69	−1.76	−1.84	0.82
No myopia	0.54	0.53	0.61	0.52
Number of myopic parents
None	0.03	−0.19	0.25	0.10
Either	0.08	−0.01	0.26	0.24
Both	−0.53	−0.09	−0.46	0.32
Maternal education level
Illiteracy	0.16	−0.10	0.40	0.09
Primary school	−0.09	−0.05	0.14	0.37
Junior high school	0.01	−0.07	0.11	0.68
Senior high school and above	0.11	−0.94	−1.68	0.52
Paternal education level
Illiteracy	−0.01	0.22	0.54	0.62
Primary school	0.07	−0.11	0.22	0.30
Junior high school	−0.06	−0.11	0.10	0.31
Senior high school and above	−0.27	−0.12	−0.25	0.97
Total	−0.04	−0.09	0.12	0.20

^aAdjusted for children’s age, gender, average parental refractive error, maternal and paternal education level, and near work time as fixed effects, and family effect as a random effect
^bIncludes outdoor sports, playing out of doors, and other outdoor leisure activities. Cut-off points were based on population tertiles for average daily hours spent outside

ISSN: 1471-2415