Table 1. Assignment of modifiable factors.

Variables	Question	Assignment
		0	1
Outdoor time	What was your daily exposure to sunlight? (Time spent in direct sunlight)	<2 h	≥2 h
Eye-use habits
Eye exercises	On average, how many times a day do you do eye exercises during school days this semester?	<2 times/day	≥2 times/day
Screen time	In the past 7 days, how much time did you spend watching TV, using computer, mobile phone and tablet every day (including surfing the Internet, watching movies, browsing the web, and playing games)?	≥2 h	<2 h
Lying down while watching/reading	In the past 7 days, have you read a book or watched a video (tablet or phone) lying down?	Often	Occasionally/never
Watching a screen in darkness	In the past 7 days, have you continued to look at your phone or tablet after turning off the lights?	Often	Occasionally/never
Posture reminding	In the past 7 days, have your parents or teachers reminded of your reading and writing posture?	Occasionally/never	Often
Eye-use environment
Desktop brightness on sunny days	Is your desktop bright enough on a sunny day?	Not very bright	Very bright
Light brightness in the evening	Do you think the lights are bright enough when you study at night?	Not bright enough	Bright enough
Seat/desk fitted for height	Do you think your desk and seat are fitted for your height?	No	Yes
Lifestyle
Sleeping duration	In the past 7 days, how long did you sleep on average per day?	< 9 h or >11 h for the grade 1–6 children <8 h or >10 h for the grade 7–11 children	≥9 h and ≤11 h for the grade 1–6 children ≥8 h and ≤10 h for the grade 7–11 children
Sedentary time	In the past 7 days, how long have you been sitting on average per school day?	≥5 h	<5 h