In the United States, ‘legal blindness’ is defined as having vision worse than 20/200 using glasses or contact lenses. If your vision is 20/200, it means that you can see at 20 feet what a person with normal vision can see at 200 feet. It is common for people who are legally blind to have some useable vision and partial sight; however, total blindness is a complete absence of any vision. The most common causes of legal blindness in the United States are glaucoma, diabetic retinopathy, macular degeneration and cataracts. Of those four causes, only a cataract can routinely be treated to improve vision.
Low vision aids and rehabilitation services can help a legally blind person function independently. Low vision aids include talking clocks, large print checks, talking scales, talking glucometers for diabetics, and closed circuit televisions (CCTV) and computer software that enlarge pictures or reading materials. Newer technology includes head-mounted cameras that place an image in front of the eyes or on a portable LCD screen.
Rehabilitation services and/or occupational therapy can help visually impaired people maintain a sense of independence by teaching them techniques to improve their functioning in the home or office environment. By combining low vision devices and rehabilitation techniques, a ‘legally blind’ person can continue to shop, attend classes, work productively, and effectively perform his or her daily tasks.