What Is Low Vision?

Low Vision DiagramWhen ordinary eyeglasses, contact lenses or intraocular lens implants cannot provide sharp sight, an individual is said to have low vision. This condition should not be confused with blindness. People with low vision still have a useful vision which can often be improved with devices. Visual impairment may be mild or severe but in each case, visual performance does not meet the individual's needs. Improving vision with visual devices is usually undertaken after your ophthalmologist has completed medical or surgical procedures or determined that such procedures are unwarranted.

What Causes Low Vision?

Though most often experienced by the elderly, people of all ages may be affected. Low vision can occur from birth defects, inherited diseases, injuries, diabetes, glaucoma, cataract, and aging. The most common cause is macular degeneration, which is a deterioration of the retina, the light-sensitive tissue in the back of the eye. Vision loss from macular degeneration is limited to central vision and fortunately does not cause total blindness since the side (peripheral) vision is not affected.

Are There Different Types of Low Vision?

Yes. Although reduced central or reading vision is most common, low vision may also result from decreased side (peripheral) vision, a reduction or loss of color vision, or the eye's inability to properly adjust to light, contrast or glare.

Different types of low vision may require different kinds of assistance. For example, people born with low vision have different needs from those who develop low vision later in life.

What Is a Low Vision Device?

A low vision device is an apparatus that improves vision. There is no single device that magically restores normal vision in all circumstances. In fact, you may need different devices for different purposes. If possible, try to determine whether a particular device is useful for you before you buy it.

Low vision devices fall into two general categories; optical and non-optical.

Optical Low Vision Devices

Optical low vision devices use lenses or combinations of lenses to provide magnification. They should not be confused with standard eyeglasses. There are five main kinds of optical devices: magnifying spectacles, hand magnifiers, stand magnifiers, telescopes and closed-circuit TV (CCTV).

Magnifying spectacles are stronger than ordinary glasses. They require that reading material be held very close, otherwise, the print is out of focus. This position may feel awkward at first, but the awkwardness can be overcome with some initial effort. Designed for close work, magnifying spectacles leave both hands free to hold reading material.

Hand magnifiers are familiar to most people. They allow you to hold reading material at a normal distance. If properly selected, hand magnifiers purchased in department or drug stores can work well.

Stand magnifiers rest on the reading material and are used with a near spectacle correction (for example, the bottom part of bifocal glasses). Some have a self-contained light source.

Telescopes are used for distance magnification. They may be handheld for viewing distant objects such as street signs or mounted in spectacles.

Closed-circuit television produces an enlarged image on a television screen. With the added advantage of adjustable magnification and contrast, closed-circuit television is often easier to use and less fatiguing than other devices.

Non-Optical Low Vision Devices

Non-optical devices include large-print books, newspapers, and magazines, check writing guides, large playing cards, enlarged telephone dials, and high contrast watch faces.

Auditory devices, such as machines that talk (timer, clocks, and computers) and even machines that scan print and read aloud, are also available.

The simplest non-optical technique is getting closer to what you want to see. Holding reading material very close to your eyes or sitting as close as one foot from the television screen will not cause eye damage, contrary to popular belief.

Is Lighting Important for People with Low Vision?

Correct lighting is as important as a low vision device. With no eye disorder, a 60-year-old person may need twice the illumination they needed at 20 to comfortably perform the same task. Remember to place the light source close to your reading material for the greatest visibility. High-intensity lights with adjustable arms work well for this purpose.

Visors and hat brims block annoying overhead light and absorptive lenses are useful in controlling glare.

What Services are Available for Low Vision Patients?

A complete eye examination by an ophthalmologist is essential. An ophthalmologist is a medical doctor (MD) educated, trained and licensed to provide total eye care, including diagnosing causes of low vision and prescribing low vision devices.

Once the cause of your low vision is determined; your ophthalmologist may suggest low vision devices or may refer you to other low vision specialists or agencies for help.

Governmental and private agencies provide social services for low vision patients. These include talking books, independent home-living instruction, and in some cases, orientation and mobility training.

For additional information contact:

The American Academy of ophthalmology is an organization of 16,000 ophthalmologists dedicated to preserving eye health and sight. Remember an ophthalmologist provides total eye care: medical, surgical and optical.