Table 2.

 Baseline characteristics of children with correctable refractive error allocated in trial, by group assignment with regard to the educational intervention. Values are numbers (percentages) unless stated otherwise

Characteristics	Education on importance of glasses (n=1648)	No education (n=1529)
Individual level
Mean (SD) age (years)	10.5 (1.1)	10.5 (1.1)
Male sex	794 (48.2)	760 (49.7)
Gansu residence	624 (37.9)	534 (34.9)
Wearing glasses at baseline*	221 (13.4)	242 (15.8)
Aware of having refractive error at baseline	744 (45.1)	731 (47.8)
Believes wearing glasses harms vision	686 (41.6)	591 (38.7)
Refractive error (diopters):
≤−2	630 (38.2)	585 (38.3)
≥−2 to −0.5	915 (55.5)	859 (56.2)
≥−0.5 to 0.5	27 (1.6)	18 (1.2)
≥0.5	76 (4.6)	67 (4.4)
Uncorrected visual acuity <6/18, in eye with better vision	936 (56.8)	877 (57.4)
One or both parents with ≥12 years of education†	338 (20.6)	311 (20.4)
Family wealth‡:
Bottom third	555 (33.7)	497 (32.5)
Middle third	560 (34.0)	496 (32.5)
Top third	532 (32.3)	534 (35.0)
Boarding at school	379 (23.0)	325 (21.3)
Both parents out-migrated for work§	172 (10.5)	155 (10.1)
Cluster level
Grade level (mean No/cluster (SD)):
Fourth grade	5.3 (4.1)	4.8 (3.9)
Fifth grade	7.8 (4.9)	7.5 (4.9)
Uncorrected visual acuity <6/18, in eye with better vision (mean No/cluster (SD))	7.4 (5.5)	7.0 (5.2)

*Defined as having glasses at school at baseline, having previously been told to bring them to school.

†Data missing for seven students.

‡Data missing for three students.

§Data missing for eight students.