Table 3.
Refractive error and vision impairment by characteristics of students (N = 4801)
| Demographics | N | Mean spherical equivalent (SD) | Myopia (%) | High myopia (%) | Vision impairment (%) |
|---|---|---|---|---|---|
| Age in years | P < 0.001 | P < 0.0001 | P < 0.0001 | P < 0.0001 | |
| ≤ 6 | 293 | −0.23 (1.25) | 35 (12.0%) | 1 (0.3%) | 9 (3.1%) |
| 7 | 345 | − 0.48 (1.29) | 45 (13.0%) | 2 (0.6%) | 23 (6.7%) |
| 8 | 359 | −0.77 (1.24) | 103 (28.7%) | 1 (0.3%) | 67 (18.7%) |
| 9 | 369 | −1.14 (1.55) | 136 (36.9%) | 3 (0.8%) | 89 (24.1%) |
| 10 | 360 | −1.55 (1.39) | 188 (52.2%) | 3 (0.8%) | 138 (38.3%) |
| 11 | 385 | −2.07 (1.74) | 245 (63.6%) | 13 (3.4%) | 193 (50.1%) |
| 12 | 353 | − 2.61 (2.01) | 267 (75.6%) | 23 (6.5%) | 222 (62.9%) |
| 13 | 374 | −2.94 (1.94) | 290 (77.5%) | 22 (5.9%) | 270 (72.2%) |
| 14 | 365 | −3.24 (2.05) | 298 (81.6%) | 38 (10.4%) | 280 (76.7%) |
| 15 | 371 | −3.72 (2.32) | 317 (85.4%) | 57 (15.4%) | 292 (78.7%) |
| 16 | 361 | −4.16 (2.21) | 326 (90.3%) | 69 (19.1%) | 313 (86.7%) |
| 17 | 370 | − 4.44 (2.53) | 332 (89.7%) | 88 (23.8%) | 319 (86.2%) |
| 18 | 370 | −4.53 (2.38) | 343 (92.7%) | 96 (26.0%) | 328 (88.7%) |
| ≥ 19 | 126 | −4.22 (2.92) | 105 (83.3%) | 36 (28.6%) | 101 (80.2%) |
| Gender | P = 0.005 | P < 0.0001 | P = 0.68 | P < 0.0001 | |
| Male | 2647 | −2.46 (2.47) | 1572 (59.4%) | 245 (9.3%) | 1381 (52.2%) |
| Female | 2154 | −2.66 (2.36) | 1458 (67.7%) | 207 (9.6%) | 1263 (58.6%) |
| Grade | P < 0.0001 | P < 0.0001 | P < 0.0001 | P < 0.0001 | |
| Kindergarten | 381 | −0.24 (1.27) | 44 (11.6%) | 2 (0.5%) | 13 (3.4%) |
| Grade 1 | 331 | −0.52 (1.17) | 49 (14.8%) | 1 (0.3%) | 22 (6.7%) |
| Grade 2 | 366 | −0.83 (1.28) | 117 (32.0%) | 1 (0.3%) | 78 (21.3%) |
| Grade 3 | 371 | −1.22 (1.55) | 143 (38.4%) | 3 (0.8%) | 97 (26.2%) |
| Grade 4 | 367 | −1.66 (1.43) | 202 (55.0%) | 5 (1.4%) | 149 (40.6%) |
| Grade 5 | 376 | −2.32 (1.85) | 259 (68.9%) | 16 (4.3%) | 214 (56.9%) |
| Grade 6 | 368 | −2.62 (1.96) | 278 (75.5%) | 21 (5.7%) | 238 (64.7%) |
| Grade 7 | 376 | −2.97 (1.95) | 296 (78.7%) | 26 (6.9%) | 273 (72.6%) |
| Grade 8 | 360 | −3.37 (2.18) | 291 (80.8%) | 45 (12.5%) | 271 (75.3%) |
| Grade 9 | 346 | −3.79 (2.24) | 304 (87.9%) | 50 (14.5%) | 286 (82.7%) |
| Grade 10 | 383 | −4.29 (2.29) | 344 (89.8%) | 84 (21.9%) | 331 (86.4%) |
| Grade 11 | 373 | −4.50 (2.54) | 341 (91.4%) | 93 (24.9%) | 326 (87.4%) |
| Grade 12 | 403 | −4.45 (2.52) | 362 (89.8%) | 105 (26.1%) | 346 (85.9%) |
| School location | P < 0.0001 | P < 0.0001 | P < 0.0001 | P < 0.0001 | |
| Urban | 2691 | − 2.83 (2.49) | 1797 (66.7%) | 304 (11.3%) | 1580 (58.7%) |
| Rural | 2110 | −2.18 (2.28) | 1233 (58.4%) | 148 (7.0%) | 1064 (50.4%) |
| School workload | P < 0.0001 | P < 0.0001 | P < 0.0001 | P < 0.0001 | |
| Low | 303 | −3.71 (2.21) | 260 (85.8%) | 45 (14.9%) | 247 (81.5%) |
| Moderate | 3841 | −2.36 (2.37) | 2310 (60.1%) | 317 (8.3%) | 1981 (51.6%) |
| High | 657 | −3.09 (2.58) | 460 (70.0%) | 90 (13.7%) | 416 (63.3%) |