Table 3.
Causes of bilateral blindness and visual impairment
| <6/18–6/60 (VI) | <6/60–3/60 (SVI) | <3/60 (Blind) | All subjects | |||||
|---|---|---|---|---|---|---|---|---|
| Avoidable | 43 | 68.3% | 19 | 61.3% | 40 | 58.8% | 102 | 63.0% |
| Preventable | 0 | 0.0% | 3 | 9.7% | 5 | 7.4% | 8 | 4.9% |
| Optic nerve injury (brain abscess, surgery) | 0 | 0.0% | 1 | 3.2% | 2 | 2.9% | 3 | 1.9% |
| Congenital rubella | 0 | 0.0% | 1 | 3.2% | 1 | 1.5% | 2 | 1.2% |
| Corneal scar | 0 | 0.0% | 1 | 3.2% | 1 | 1.5% | 2 | 1.2% |
| Vitamin A deficiency | 0 | 0.0% | 0 | 0.0% | 1 | 1.5% | 1 | 0.6% |
| Treatable | 43 | 68.3% | 16 | 51.6% | 35 | 51.5% | 94 | 58.0% |
| Refractive error | 26 | 41.3% | 2 | 6.5% | 3 | 4.4% | 31 | 19.1% |
| Cataract | 7 | 11.1% | 8 | 25.8% | 14 | 20.6% | 29 | 17.9% |
| Glaucoma | 0 | 0.0% | 0 | 0.0% | 12 | 17.6% | 12 | 7.4% |
| Amblyopia–refractive | 4 | 6.3% | 3 | 9.7% | 3 | 4.4% | 10 | 6.2% |
| Vernal keratoconjunctivitis | 3 | 4.8% | 2 | 6.5% | 2 | 2.9% | 7 | 4.3% |
| Subluxed lens from Marfan syndrome | 3 | 4.8% | 1 | 3.2% | 0 | 0.0% | 4 | 2.5% |
| Unknown (bilateral enucleation) | 0 | 0.0% | 0 | 0.0% | 1 | 1.5% | 1 | 0.6% |
| Unavoidable | 20 | 31.7% | 12 | 38.7% | 28 | 41.2% | 60 | 37.0% |
| Optic nerve atrophy | 2 | 3.2% | 2 | 6.5% | 8 | 11.8% | 12 | 7.4% |
| Albinism | 6 | 9.5% | 3 | 9.7% | 1 | 1.5% | 10 | 6.2% |
| Retinal dystrophy | 4 | 6.3% | 1 | 3.2% | 2 | 2.9% | 7 | 4.3% |
| Disorganised | 1 | 1.6% | 2 | 6.5% | 4 | 5.9% | 7 | 4.3% |
| Unknown—normal examination | 5 | 7.9% | 1 | 3.2% | 1 | 1.5% | 7 | 4.3% |
| Microphthalmia | 0 | 0.0% | 0 | 0.0% | 5 | 7.4% | 5 | 3.1% |
| Aniridia | 1 | 1.6% | 1 | 3.2% | 2 | 2.9% | 4 | 2.5% |
| Cerebral hypoxia/injury | 0 | 0.0% | 1 | 3.2% | 2 | 2.9% | 3 | 1.9% |
| Optic nerve hypoplasia | 0 | 0.0% | 1 | 3.2% | 1 | 1.5% | 2 | 1.2% |
| Anophthalmos | 0 | 0.0% | 0 | 0.0% | 1 | 1.5% | 1 | 0.6% |
| Cornea plana/sclerocornea | 1 | 1.6% | 0 | 0.0% | 0 | 0.0% | 1 | 0.6% |
| Goldenhar syndrome | 0 | 0.0% | 0 | 0.0% | 1 | 1.5% | 1 | 0.6% |
| Total | 63 | 100.0% | 31 | 100.0% | 68 | 100.0% | 162 | 100.0% |
VI, visual impairment; SVI, severe visual impairment.