Low vision is a condition that involves an impaired ability to see (particularly central vision) that is unresolved or uncorrected with traditional eyeglasses, contact lens, intraocular lens implants, or corrective surgery. However, in some cases, people with low vision may be aided with special visual devices.
There are a variety of different causes of low vision, including the following:
Macular degeneration (the most common cause of low vision. This involves damage to the central vision making it difficult to read, drive, or perform other daily activities that need fine, central vision)
Aging (Aging is a risk factor for low vision. However, people of any age may be affected.)
Congenital defects (present at birth)
Disease (including diabetes)
Other eye diseases (for example, glaucoma or cataracts)
In most cases, people with low vision have disabled central vision (also called reading vision). Yet, there are other types of low vision that may include the following:
Disabled or partial peripheral vision
Disabled or partial color vision
Disabled or partial ability to adjust to different light levels
Disabled or partial ability to adjust to different contrasts
Low vision cannot be improved by more traditional methods (such as the use of eyeglasses or contact lenses). People with low vision often rely on a number of different instruments called low-vision devices. Low-vision devices, categorized as either optical or non-optical, help to improve visual ability for millions of people every day.
Simply stated, optical low-vision devices involve the use of one of many types of lenses to improve vision. For example:
Magnifying devices such as magnifying eyeglasses, hand magnifiers, magnifying lamps, or telescopic viewing devices
Closed-circuit television involves enlarged images, exaggerated contrasts, and adjustable magnification
Non-optical low-vision devices help bring images closer to the eyes. This may include the use of any or all of the following:
Larger-print items such as magazines, newspapers, books, calendars, address books, cookbooks, dictionaries, games, playing cards, sheet music, or street signs
Larger, illuminated watches and clocks
Instruments that provide voice instruction. For example, computers, smart phones, tablets, electronic books. Many of these read material aloud, magnify, or illuminate material. Many of these products let you change word size and adjust lighting.
Instruments that provide voice information. For example, blood pressure cuffs, blood sugar machines, clocks, timers, calculators, scales, or key chains.