Table 5.

Multivariate logistic regression analysis of factors affecting the occurrence of blurred vision.

Variable	Odds ratio (95% confidence interval)	P value
Age/years	1.1 (0.99 : 1.3)	0.06
Gender
Males	1
Females	1.2 (0.8 : 1.7)	0.38
Total daily screen-hours	1.0 (0.9 : 1.2)	0.37
Screen-years	0.98 (0.88 : 1.1)	0.63
Commonest used screen
Desktop computer screen	1
Apple smartphone	2.4 (1.0 : 5.5)	0.04
Android smartphone	2.0 (0.95 : 4.2)	0.07
Laptop	2.1 (0.99 : 4.5)	0.054
iPad/tablet/other screens	0.9 (0.2 : 3.9)	0.88
Screen brightness (%)	1.00 (0.99 : 1.0)	0.44
Study medicine using
Books	1
Screens/both	1.6 (0.97 : 2.7)	0.07
Main screen-time purpose is
Medicine	1
Social	1.3 (0.8 : 1.9)	0.30
Previous DED diagnosis	2.1 (1.2 : 3.8)	0.01
Refractive errors/wearing	2.0 (1.4 : 2.8)	<0.0001
Contact lenses wearer	0.7 (0.3 : 1.6)	0.41
Poor lighting conditions	2.6 (1.7 : 4.1)	<0.0001
Watch screen in the dark	1.0 (0.68 : 1.6)	0.87
Upper screen edge at/above horizontal eye level	2.0 (1.3 : 2.9)	0.001
Close eye-screen distance	2.1 (1.5 : 3.0)	<0.0001
Uncomfortable seating postures	1.3 (0.7 : 2.3)	0.38
Texting with both thumbs	1.7 (1.2 : 2.5)	0.004
Screen-glare	2.8 (1.2 : 6.5)	0.02
Poor screen-resolution or design	1.9 (0.8 : 4.4)	0.13
Small font size	1.5 (0.97 : 2.3)	0.07