Prevalence in numbers (%) of visual impairments in VLBW children and normal birthweight controls
| VLBW (n=137) | Controls (n=163) | χ2 | P value | |
|---|---|---|---|---|
| Abnormal visual acuity: | ||||
| 6 m | 23 (17) | 13 (8) | 5.47 | 0.02 |
| 0.3 m | 19 (14) | 10 (6) | 5.0 | 0.025 |
| Strabismus | 13 (9.5) | 4 (2.5) | 6.89 | 0.009 |
| Spectacle wear | 31 (23) | 21 (13) | 4.79 | 0.03 |
| Myopia | 20 (15) | 13 (8) | 3.25 | 0.07 |
| Hypermetropia | 11 (8) | 8 (5) | 1.18 | 0.27 |
| Stereopsis: | ||||
| Abnormal | 50 (36) | 24 (15) | 18.9 | 0.00001 |
| Absent | 27 (20) | 9 (5.5) | 14.1 | 0.0002 |
| Poor contrast sensitivity at spatial frequency: | ||||
| 1.5 CPD | 23 (17) | 8 (5) | 10.9 | 0.0009 |
| 3 CPD | 25 (18) | 6 (4) | 16.5 | 0.00005 |
| 6 CPD | 44 (32) | 19 (12) | 18.1 | 0.00002 |
| 12 CPD | 51 (37) | 20 (12.5) | 24.8 | <0.00000 |
| 18 CPD | 62 (45) | 25 (16) | 31.3 | <0.00000 |
| Any | 66 (48) | 31 (19) | 27.8 | <0.00000 |