Health Library : Eye Care

Low-Vision Devices

What is low vision?

Low vision is a condition that involves a minimal 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.

What causes low vision?

There are a variety of different causes of low vision, including, but not limited to, the following:

• Macular degeneration (the most common cause of low vision; involves damage to a person's central vision making it difficult to read, drive, or perform other daily activities that require 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)
• Injury
• Disease (including diabetes)
• Other eye diseases (for example, glaucoma or cataracts)

What are the different types of low vision?

Although, in most cases, people with low vision have disabled central vision (also called reading vision), there are other types of low vision which may include the following:

• Disabled or partial peripheral vision
• Disabled or partial color vision
• Disabled or partial ability to adjust to different light settings
• Disabled or partial ability to adjust to different contrasts
• Glared vision

What are low-vision devices?

Because 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 the use of a number of different instruments called low-vision devices, and tailored equipment for improved vision. Low-vision devices, categorized as either optical or nonoptical, help to improve visual ability for millions of people every day.

What are optical low-vision devices?

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 or CCTV involves enlarged images, exaggerated contrasts, and adjustable magnification

What are nonoptical low-vision devices?

Nonoptical 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
• Writing guides
• Instruments that provide voice instruction (for example, computers)
• Instruments that provide voice information (for example, clocks, timers, calculators, scales, or key chains)

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