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Low vision

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People with normal visual acuity have what is known as 20/20 vision, meaning that they can see normally what should be able to be seen at 20 feet. A person with 20/60 vision, however, can only see what a normal person could see at 60 feet if they move up to 20 feet[1].

The World Health Organization defines vision impairment is having any uncorrectable reduced vision where:

  • 20/30 to 20/60 is considered mild vision loss, or near-normal vision
  • 20/70 to 20/160 is considered moderate visual impairment, or moderate low vision
  • 20/200 to 20/400 is considered severe visual impairment, or severe low vision
  • 20/500 to 20/1,000 is considered profound visual impairment, or profound low vision
  • less than 20/1,000 is considered near-total visual impairment, or near total blindness
  • no light perception is considered total visual impairment, or total blindness[2]

"There are other important vision skills, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and color vision that contribute to your overall visual ability."[3]

"In the United States, any person with vision that cannot be corrected to better than 20/200 in the best eye, or who has 20 degrees or less of visual field remaining, is considered legally blind."[4]

In 2002, the three leading causes of low vision and blindness world-wide were cataracts, glaucoma, and age-related macular degeneration (AMD).[5]


External Links


References

  1. http://www.aoa.org/Visual-Acuity.xml
  2. http://www.aoa.org/x5240.xml
  3. http://www.aoa.org/Visual-Acuity.xml
  4. http://www.aoa.org/x5240.xml
  5. http://www.who.int/mediacentre/factsheets/fs282/en/