Ophthalmology exams often test your epidemiological knowledge of visual impairment and blindness. This page will summarise the important facts and discuss the registration of visual impairment in the UK.
Visual Impairment
The department of health in the UK classifies patients with visual impairments as severe (blind) or partial. The criteria for this classification is summarised below and revolves around visual acuity (VA) and visual field defects (VFD).
Severe Sight Impairment (blind)
One of:
- VA < 3/60
- VA 3/60-6/60 AND a severe VFD such as tunnel vision
- VA ≥ 6/60 with significant VFD, particularly affecting the lower fields
Sight Impaired (partial impairment)
One of:
- VA 3/60-6/60 with full VF
- VA 6/18-6/24 with moderate VFD or loss of central vision
- VA ≥ 6/18 with a significant VFD such as hemianopia
Global Vision
Category |
Condition |
|---|---|
Most common cause of blindness in the world |
Cataract |
Most common cause infective blindness in the world |
Trachoma (1st) Onchocerciasis (2nd) |
Most common cause of visual impairment in the world |
Refractive error |
Most common type of colour blindness |
Red-green |
Most common cause of nutritional blindness |
Vitamin A deficiency → nyctalopia |
Most common cause of irreversible blindness in the world |
Glaucoma |
