Advertisement

What is legal blindness?

Ray F. Gariano, MD
Ophthalmology
Legally blind is defined as having vision in either eye that is no better than 20/200. This level of vision makes some activities -- such as driving a car or reading a newspaper -- impossible without special visual aids. On the other hand, a person who is legally blind may still be able to do things like cook, watch television read large-print books and safely remain mobile inside and outside of the home.

Legal blindness is defined as having less than 20/200 vision while wearing corrective lenses. The following conditions can lead to blindness:

  • Cataracts are a cloudiness in the lens that can block light from reaching the retina. Cataracts become more common as we age, but it is not solely tied to age. Babies can be born with a cataract. Cataracts can require surgery, where the lens is removed and replaced with an intraocular lens.
  • Glaucoma - If certain eye fluids do not drain out correctly, pressure build in the eye. This causes cells and nerve fibers to die. It can be treated with medications and surgery.
  • Diabetic retinopathy - People with diabetes can get blocked blood vessels, leaking blood vessels and certain scarring that can lead to blindness. These conditions can be treated with laser surgery.
  • Macular degeneration - In some people, the macula (responsible for fine detail in the center of vision) deteriorates with age for unknown reasons. This can cause loss of central vision. It can sometimes be helped with laser surgery.
  • Trauma – Any eye trauma, including chemical injuries, can cause damage to the eyes that can prevent adequate vision.
  • Retinitis pigmentosa is an inherited disease that can cause a degeneration of the retina and excess pigment. First, it causes night blindness, then tunnel vision. Often, the condition gradually progresses to total blindness. It has no known treatment.
  • Trachoma is an infection caused by the organism Chlamydia trachomatis. It is a common cause of blindness in many parts of the world but is rare in the United States. It is treated with antibiotics.

Continue Learning about Visual Impairments

How does Braille help people with visual impairment?
Dr. Jeanne Morrison, PhDDr. Jeanne Morrison, PhD
Braille is a language that is used to represent letters, numbers, punctuation marks and even entire ...
More Answers
What is the rate of incidence for visual impairments?
Diana MeeksDiana Meeks
Because there are many different kinds of visual impairments it is difficult to measure the rate of ...
More Answers
How can I improve the display on a mobile device if I'm visually impaired?
Multiple Sclerosis FoundationMultiple Sclerosis Foundation
Contrast is a very important feature for people who are visually impaired, but it is often overlooke...
More Answers
Can a GPS help a blind person to be active?
Dr. Jeanne Morrison, PhDDr. Jeanne Morrison, PhD
Some people are finding that technology can help those with visual impairment to live more active li...
More Answers

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.