T17 2020/02/23 05:47:44.053746 GMT+0530
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This topic provides introductory information about blindness

WHO definition of blindness

For International comparison, WHO has defined blindness at the level of 3/60 or   inability to count fingers at a distance of 3 meters or 10 feet.

Definition of blindness under National Programme for Control of Blindness

Blindness is defined under following headings:

Simple Definition: Inability of a person to count fingers from a distance of 6 meters or 20 feet

Technical Definition

  • Vision 6/60 or less with the best possible spectacle correction
  • Diminution of field vision to 20° or less in better eye
  • Types of blindness

    • Economic blindness:
    • Social blindness: Vision 3/60 or diminution of field of vision to 10°
    • Manifest blindness: Vision 1/60 to just perception of light
    • Absolute blindness: No perception of light
    • Curable blindness: That stage of blindness where the damage is reversible by prompt management e.g. cataract
    • Preventable blindness: The loss of blindness that could have been completely prevented by institution of effective preventive or prophylactic measures e.g. xerophthalmia, trachoma, and glaucoma
    • Avoidable blindness: The sum total of preventable or curable blindness is often referred to as avoidable blindness.

    Reasons for prevalence of blindness in India

    According to the National blindness survey (2006-2007, the prevalence of blindness in India is 8% in individuals above 50 years of age in India. The major reasons for prevalence of blindness in India are:

    • The overall increase in the size of the population
    • The life expectancy for both males and females has steadily increased
    • A major proportion of aged population in rural areas have poor access to eye care facilities in India
    • Inadequate availability of trained health personnel. Further, the services of available ophthalmic surgeons in the country are not being adequately utilized. Many ophthalmologists are purely working in administrative jobs and similar proportion is posted at peripheral units with no ophthalmic equipments.
    • The poor nutritional status of mothers and young children predisposes the pre-school children to nutrition blindness. However, it is heartening to note that prevalence of nutritional blindness has decreased tremendously over the past few years
    • Adverse environmental conditions and domestic unhygienic conditions predispose to high infection rates
    • Lack of community awareness and poor health seeking behavior
    • The prevalence of myths and misconception about surgeries

    Main causes of blindness in India



    Refractive errors:




    Posterior segment disorder:


    Surgical Complication:


    Corneal blindness:


    Posterior capsular opacification:




    Source : National Programme for Control of Blindness

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