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 |