What Are Contact Lenses?
Contact lenses are thin, clear plastic disks you wear in your eye to improve your vision. Contacts float on the tear film that covers your cornea.
Like eyeglasses, contact lenses correct vision problems caused by refractive errors. A refractive error is when the eye does not refract (bend or focus) light properly into the eye resulting in a blurred image.
Contacts can improve vision for people with these refractive errors:
Types of Contact Lenses
Contacts are made from many kinds of plastic. The two most common types of contact lenses are hard and soft.
Hard contact lenses
The most common type of hard contact lens is a rigid gas-permeable (RGP) lens. These lenses are usually made from plastic combined with other materials. They hold their shape firmly, yet they let oxygen flow through the lens to your eye.
RGP lenses are especially helpful for people with astigmatism and a condition called keratoconus. This is because they provide sharper vision than soft lenses when the cornea is unevenly curved. People who have allergies or tend to get protein deposits on their contacts may also prefer RGP lenses.
Soft contact lenses
Most people choose to wear soft contact lenses. This is because they tend to be more comfortable and there are many options. Here are some types of soft lenses.
Daily wear contacts. You wear these when you are awake and remove them when you go to sleep. Many are disposable, meaning that you wear a new pair of contacts each day. Or you might choose contacts that last longer and only need to be replaced once a week, every two weeks or every month. Some ophthalmologists recommend disposable daily wear contacts if you use them just once in a while.
Extended wear contacts. You can wear these while you sleep, but they need to be removed for cleaning at least once a week. Fewer eye doctors recommend these contacts because they increase the chance of getting a serious eye infection.
Toric contacts. These can correct vision for people with astigmatism, though not as well as hard contact lenses. Toric lenses can be for daily or extended wear. But they often cost more than other types of soft contact lenses.
Colored (tinted) contacts. Vision-correcting contact lenses can be tinted to change the color of your eye. You can get them as daily wear, extended wear, and toric lenses.
Decorative (cosmetic) contacts. These lenses change the look of your eye but do not correct vision. They include colored contacts and lenses that can make your eyes look like vampires, animals or other characters. Also, they are used to hide certain eye problems either present from birth or caused by injuries. Even though they do not correct vision, you need a prescription for decorative contacts. To avoid getting dangerous eye infections, these lenses must be treated like prescription contacts. This means cleaning them regularly and thoroughly as directed.
Decorative contact lenses can lead to serious eye problems.
Your eyes are very important—and very delicate. Make sure your contact lenses are medically safe and FDA-approved.
Contacts are not fashion accessories or cosmetics. They are medical devices that require a prescription from an eye care professional.
Non-prescription costume contacts can cause cuts, open sores and potentially blinding infections in your eyes. In addition to suffering severe pain, you may need surgery (such as a corneal transplant). In some cases, you could go blind.
Want decorative contact lenses? Ask an eye care professional.
Other types of contact lenses
Contacts for presbyopia. Presbyopia contacts are designed to correct the normal vision problems people get after age 40, when it becomes harder to see close objects clearly. There are different options for these corrective lenses.
These options include: bifocal or multifocal contact lenses, and monovision correction, where one eye wears a near vision lens and the other eye wears a distance vision lens.
Hybrid contact lenses. These lenses have a rigid center surrounded by a soft outer ring. It combines the crisp vision of a hard lens with the comfort of a soft lens.
Scleral contact lenses. These gas permeable (GP) lenses stretch over the cornea and rest on the sclera or white part of the eye. Their large size helps correct vision problems caused by an irregularly shaped cornea (like corneal scars, keratoconus or surgery). But others may find they provide better comfort than normal GP lenses.
Bandage lenses. These contacts do not have a prescription built into them. Instead, they cover the surface of your cornea for comfort after an injury or surgery.