Sources

Definitions

Criteria

World Health Organization [15]

Inability to reach near normal performance with visual aids (defined in terms of low vision).

Best visual acuity < 6/18

US Social Security Administration [17]

Ineligibility to obtain a driver’s license.

Best visual acuity < 20/40 (6/12)

The Beaver Dam Eye Study [18]

Inability to read a newspaper (mild impairment) or to reach near normal performance with visual aids (moderate impairment).

Mild visual impairment:

Best visual acuity 6/12 to 6/18;

Moderate visual impairment:

Best visual acuity < 6/18

Leat et al., 1999 [16]

Inability to read with near-normal fluency.

Best visual acuity < 6/7.5;

Horizontal visual field < 146˚ or 109˚;

Contrast sensitivity < 1.5