Eyeglasses and Your Eyes

• What types of lenses are available?
• What are multifocal lenses?
• How should you care for your glasses?

Eyeglasses today are fashion accessories, as stylish as purses and belts. In fact, you'll find familiar names - Calvin Klein and Bill Blass to name just two - on your choice of frames these days. So don't fret if contact lenses irritate your eyes. Instead, scope out the latest fashion frames to give your face a fresh look.

What Types of Lenses Are Available?

As technology advances so, too, do eyeglass lenses. In the past, eyeglass lenses were made exclusively of glass. Today most eyeglasses are made of high-tech plastics. These new lenses are lighter, do not break as easily as glass lenses, and can be treated with a filter to shield your eyes from damaging ultraviolet light.

The following modern eyeglass lenses are lighter, thinner, and more scratch-resistant than glass lenses or the older, common plastic lenses.

• Polycarbonate lenses. These eyeglass lenses are impact resistant and are a good choice for people who regularly participate in sporting activities, work in a job environment in which their eyeglasses may be easily scratched or broken, and for children who may easily drop and scratch their eyeglasses.
• Photochromic and tinted lenses. Made from either glass or plastic, these eyeglasses change from clear to tinted when exposed to sunlight. This eliminates the need for prescription sunglasses.
• High index plastic lenses. Designed for people who require strong prescriptions, these eyeglass lenses are lighter and thinner than the standard, thick "coke bottle" lenses that may otherwise be needed.
• Aspheric lenses. These eyeglass lenses are unlike typical lenses, which are spherical in shape. Aspheric lenses are made up of differing degrees of curvature over its surface, which allows the lens to be thinner and flatter than other lenses. This also creates an eyeglass lens with a much larger usable portion than the standard lens.

The type of vision problem that you have determines the shape of the eyeglass lens. For example, a lens that is concave, or curves inward, is used to correct nearsightedness , while a lens that is convex, or curves outward, is used to correct farsightedness . To correct astigmatism , which is caused by distortions in the shape of the cornea, a cylinder shaped lens is frequently used. Simply put, the eyeglass lens is a tool you use to focus light appropriately on your retina.

What Are Multifocal Eyeglass Lenses?

People who have more than one vision problem often need eyeglasses with multifocal lenses. Multifocal lenses, such as bifocals and trifocals, are eyeglass lenses that contain two or more vision-correcting prescriptions. In years past, you could spot a multifocal lens by the line separating the two sections. But today multifocal lenses can be made to look seamlessly attractive. No one but you and your doctor will ever know!

Bifocals. Bifocals are the most common type of multifocal lens. The eyeglass lens is split into two sections; the upper part is for distance vision and the lower part for near vision. They are usually prescribed for people over the age of 40 whose focusing ability has declined due to presbyopia.

Trifocals. Trifocals are simply bifocals with a third section used for people who need help seeing objects that are within an arm's reach.

If you have questions about which eyeglass lens is right for you, talk to your eye doctor. He or she can help you choose the lens that best fits your lifestyle and vision needs.

How Should You Care for Your Eyeglasses?

• Always store eyeglasses in a clean, dry place away from potential damage.
• Clean your eyeglasses with water and a non-lint cloth, as necessary, to keep them spot free and prevent distorted vision.
• See your doctor annually to check your eyeglass prescription.

Remember, eyeglasses can correct most common vision problems simply, without surgery, eyedrops or fuss.

Reviewed by the doctors at The Cleveland Clinic Cole Eye Institute.

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Edited by Charlotte E. Grayson, MD, WebMD, October 2004.

Portions of this page © The Cleveland Clinic 2000-2005

Last Editorial Review: 6/29/2005