Table 1

Baseline characteristics of 910 students with correctable myopia allocated in a trial of eyeglasses provision, by intervention group assignment

VariableControl group
(n=434* at 16 schools)
Intervention group
(n=476*at 15 schools)
P value, control versus interventionMissing data,
n (%)
Age (years), mean (SD)13.64 (1.19)13.49 (1.08)0.2190
Baseline uncorrected visual acuity (LogMAR)†0.64 (0.25)0.64 (0.26)0.9740
Total time spent on phone (hours/day)0.87 (1.05)0.97 (1.27)0.5262 (0.22)
Total time spent on computer (hours/day)0.62 (1.02)0.51 (1.03)0.3840
Male gender, n (%)193 (44.47)211 (44.33)0.9690
Only child in family, n (%)42 (9.68)34 (7.14)0.2370
Believes wearing eyeglasses harms vision, n (%)168 (38.71)218 (45.80)0.1731 (0.11)
Baseline eyeglasses ownership, n (%)‡145 (33.41)192 (40.34)0.3140
VA <6/18 both eyes, n (%)314 (72.35)353 (74.16)0.6920
Boarding at school, n (%)306 (70.51)371 (77.94)0.1550
Both parents migrant out, n (%)25 (5.76)25 (5.25)0.7549 (0.99)
At least one family member wearing eyeglasses, n (%)123 (28.34)157 (32.98)0.1613 (0.33)
Rural residence, n (%)401 (92.40)459 (96.43)0.0911 (0.11)
At least one parent with ≥9 years of education, n (%)399 (91.94)449 (94.33)0.2901 (0.11)
Mean (SD) refractive error (dioptres), n (%)0.23132 (3.52)
 ≤−2223 (51.38)274 (57.56)
 −2 to −0.5181 (41.71)179 (37.61)
 0.5–0.519 (4.38)16 (3.36)
 ≥0.511 (2.53)7 (1.47)
Blackboard use, n (%)0.6760
 <Half of teaching213 (49.08)196 (41.18)
 Half of teaching96 (22.12)129 (27.10)
 >Half of teaching125 (28.80)151 (31.72)
  • *Data are presented as mean (SD) or number (%) unless otherwise stated.

  • †0.1 change in LogMAR indicates 1 line change on the vision chart.

  • ‡Defined as being able to produce eyeglasses at school, having been told the day before to bring them.

  • LogMAR, logarithm of the minimum angle of resolution; VA, visual acuity.