Over three million people in the United States do not have normal vision even with corrective lenses. If ordinary eyeglasses do not provide clear vision, one is said to have low vision. This should not be confused with blindness. People with low vision still have useful vision that can often be improved with low-vision devices.
Low vision can result from birth defects, inherited diseases, injuries, diabetes, glaucoma or macular degeneration. Although reduced central or reading vision is most common, a person can have low vision in their side (peripheral) vision, or a loss of color vision or contrast sensitivity.
Low vision devices or aides are available in optical and non-optical types. Optical 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 television. Different devices may be needed for different purposes. If possible, try the optical device before purchasing it and be sure you understand how to use it.
The simplest non-optical technique is to bring the object of interest closer. Non-optical low vision devices include large print books, check writing guides, enlarged phone dials, talking appliances (timers, clocks, computers), and machines that scan print and read out loud.