Table 1

WHO classification of levels of visual impairment (adapted from International Classification of Diseases, 10th revision3)

Level of visual impairmentCategory of visionVisual acuity in better eye with optical correction
Slight if visual acuity < 6/7.5Normal vision6/18 or better
Visual impairment Low vision< 6/18 to 6/60
Severe visual impairment Low vision< 6/60 to 3/60
Blind Blindness< 3/60 to no light perception
Visual field ⩽ 10 degrees around central  fixation