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Encyclopedia entry: blindness
- Article from:
- The Oxford Companion to the Body
- Author:
Copyright© The Oxford Companion to the Body 2001, originally published by Oxford University Press 2001. (Hide copyright information)
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blindness
Surprisingly, blindness rarely means total absence of light perception. Most definitions of blindness are based on measurement of
visual acuity
(the ability to read letters at a certain distance) and assessment of the ability of the person to carry out tasks needing vision. In the UK, the National Assistance Act 1948 states that a person can be certified as blind if they are ‘so blind that they cannot do any work for which eyesight is essential’. This rather circular definition refers to ‘any work’ and not just the person's normal job or one for which he has been specially trained.
Visual acuity is usually tested by asking the patient to read letters of ...