- Eye Diseases Pictures Slideshow
- Pink Eye Slideshow Pictures
- Eyes and Eye Conditions Quiz
- Patient Comments: Blindness - Causes
- Patient Comments: Blindness - Diagnosis
- Patient Comments: Blindness - Legally Blind
- Find a local Eye Doctor in your town
- Blindness facts
- What is blindness?
- When is one considered legally blind?
- What are the different types of blindness?
- What causes blindness?
- What are risk factors for blindness?
- What are signs and symptoms of blindness?
- What specialists treat blindness?
- How do health-care professionals diagnose blindness?
- What are treatments for blindness?
- What is the prognosis for blindness?
- Is blindness preventable?
Quick GuideCommon Eye Problems and Infections
What is blindness?
Blindness is defined as the state of being sightless. A blind individual is unable to see. In a strict sense the word "blindness" denotes the inability of a person to distinguish darkness from bright light in either eye. The terms blind and blindness have been modified in our society to include a wide range of visual impairment. Blindness is frequently used today to describe severe visual decline in one or both eyes with maintenance of some residual vision.
Vision impairment, or low vision, means that even with eyeglasses, contact lenses, medicine, or surgery, someone doesn't see well. Vision impairment can range from mild to severe. Worldwide, between 300 million-400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind. Approximately 80% of blindness occurs in people over 50 years of age.
When is one considered legally blind?
Legal blindness is not a medical term. It is defined by lawmakers in nations or states in order to either limit allowable activities, such as driving, by individuals who are "legally blind" or to provide preferential governmental benefits to those people in the form of educational services or monetary assistance. Under the Aid to the Blind program in the Social Security Act passed in 1935, the United States Congress defined legal blindness as either central visual acuity of 20/200 or less in the better eye with corrective glasses or central visual acuity of more than 20/200 if there is a visual field defect in which the peripheral field is contracted to such an extent that the widest diameter of the visual field subtends an angular distance no greater than 20 degrees in the better eye. Blindness in one eye is never defined as legal blindness if the other eye is normal or near-normal.
It is estimated that more than 1 million people in the United States meet the legal definition of blindness.