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Visual impairment criteria*
| WHO | US | US SSA | |
|---|---|---|---|
| Low vision | VA < 0.3 (20/70) and/or a constriction of the central visual field to < 20° | VA < 0.5 (20/40). | MD ≤ -22 dB in both eyes. |
| Blindness | VA < 0.05 (20/400) and/or a constriction of the central visual field to < 10° | VA ≤ 0.1 (6/60) and/or a constriction of the central visual field to < 20° | |
*Visual impairment = low vision + blindness.
VA, visual acuity; MD, mean deviation; dB, decibel.
