Eyeglasses correct vision problems, such as nearsightedness, farsightedness, astigmatism, and presbyopia by focusing light more appropriately on the retina.

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 used. Presbyopia requires bifocal or multifocal lenses.

What are multifocal lenses?

People who have more than one vision problem often need glasses with multifocal lenses. Multifocal lenses, bifocals, trifocals, or progressive lenses are lenses that contain two or more vision-correcting prescriptions.

What types of lenses are available?

In the past, eyeglass lenses were made exclusively of glass; today, however, most lenses are made of plastic. Plastic lenses are lighter, do not break as easily as glass lenses, and can be treated with a filter to keep out ultraviolet light, which can be damaging to the eyes. However, glass lenses are more resistant to scratches than plastic ones.

As technology advances so, too, do eyeglass lenses. The following modern lenses are lighter, thinner, and more scratch-resistant than the common plastic and glass lenses:

If you have questions about which type of lens is right for you, talk to your eye doctor. He or she can help you choose the lenses that are best for you based on your lifestyle and vision needs.

Caring for your eyeglasses

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

How often should I change my glasses?

Generally an eyeglass prescription is good for a year, sometimes longer. Some circumstances may lead to a need for new glasses at a shorter interval. They include:

If your vision is decreasing in one or both eyes, you should check to see if you need new glasses or to be sure that there is no significant disease that may require treatment.



This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This document was last reviewed on: 3/15/2015