Alternative names
Loss of vision

Blindness is the loss of vision, not correctable with lenses. Blindness can be partial, with loss of only part of the vision. It can also be complete, in which case there is no perception of light. People with vision worse than 20/200 or a field of vision of less than 20 degrees in the better eye are considered legally blind.

Common Causes

Blindness has many causes. In the United States, the leading causes are diabetes, glaucoma, macular degeneration, and accidents (such as chemical burns or injuries from bungie cords, fishing hooks, fireworks, racket balls, and similar objects).

Worldwide, the leading causes of blindness are cataracts, onchocerciasis (“river blindness”), trachoma, leprosy, and vitamin A deficiency.

Other causes include:

  • blocked blood vessels  
  • complications of premature birth (retrolental fibroplasia)  
  • complications of eye surgery  
  • lazy eye  
  • optic neuritis  
  • stroke  
  • Tay-Sachs disease  
  • retinitis pigmentosa  
  • retinoblastoma  
  • lead poisoning  
  • optic glioma

Home Care
It is important for a blind person to be able to dress, eat, function independently, and stay safe. Many services are available that provide the training and support that allow blind people to function independently.

Call your health care provider if

Sudden vision loss is always an emergency, even you have not completely lost all vision. Loss of vision should never be ignored, thinking it will get better.

Contact an ophthalmologist or go to the emergency room immediately. Most serious forms of vision loss are painless, and the absence of pain in no way diminishes the urgent need to get medical care. Many forms of vision loss only have a short amount of time where they can be successfully treated.

What to expect at your health care provider’s office
A complete and thorough eye examination will be performed. The treatment plan will depend on the cause.

Johns Hopkins patient information

Last revised: December 4, 2012
by Harutyun Medina, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.