Contact lenses are thin, clear disks of plastic that float on the surface of the eye. They correct vision like eyeglasses do and are safe when used with care. Contact lenses are used to correct the same conditions that eyeglasses do: myopia (nearsightedness), hyperopia (farsightedness), astigmatism (blurred vision due to the shape of the cornea) and presbyopia (inability to see up close).

Millions of people around the world wear contact lenses. Depending on your lifestyle, your motivation and the health of your eyes, contact lenses may provide a safe and effective alternative to eyeglasses when used with proper care and maintenance.

There are two general types of contact lenses: hard and soft. The hard lenses most commonly used today are rigid, gas-permeable lenses (RGP for short). They are made of plastics and other materials such as silicone or fluoropolymers. Hard lenses hold their shape; yet allow the free flow of oxygen through the lenses to the cornea. RGP lenses may be the best choice when the cornea has enough astigmatism (is shaped like an egg instead of an orange) that a soft lens will not provide sharp vision. They may also be preferable when a person has allergies or tends to form protein deposits on his or her contacts.

Soft lenses are the choice of most contact lens wearers. These lenses are comfortable and come in many versions, depending on how you want to wear them.

Daily-wear lenses are the least expensive, are removed nightly, and are replaced on an individualized schedule. They should not be used as an extended-wear lens.

Extended-wear lenses are worn overnight but are removed at least weekly for thorough cleaning and disinfection. They are being recommended less frequently, since there is a greater risk of corneal infection with any overnight wear of contact lenses.

Disposable-wear lenses are more expensive, but convenient. They are removed nightly and replaced on a daily, weekly, or monthly basis. Disposable lenses are sometimes recommended for people with allergies and for those who tend to form deposits on their lenses.

Cosmetic or decorative contact lenses are colored contacts that change the appearance of your eye color. Decorative lenses are available by prescription and should only be worn after an eye exam and fitting by qualified eye care professional. Over-the-counter decorative contacts, are illegal and pose a serious danger to your eye heath. They can cause eye injury, eye infection, and vision loss.

Toric soft contact lenses can correct astigmatism but sometimes not as well as RGP lenses do.

Bifocal or multifocal contact lenses are available in both soft and RPG varieties. They can correct nearsightedness, farsightedness, and astigmatism in combination with presbyopia.