Contact lens wearers have an increased risk for serious eye infections and injury to the cornea. Small objects that get into the eye may become trapped under a lens and scratch the cornea. Pinkeye (conjunctivitis) or other minor eye infections are likely to irritate your eyes and make wearing contacts uncomfortable and unsafe.
Symptoms of possible problems with contacts include redness, pain or burning in the eye, drainage, blurred vision, or sensitivity to light (photophobia). If you are having problems, remove your lenses and disinfect them. If symptoms persist longer than 2 to 3 hours after removing and cleaning your contacts, call your eye doctor.
Daily-wear soft lenses are removed and cleaned at night and reinserted in the morning. They take less time to get used to than hard lenses, but they are less durable.
Extended-wear lenses can be worn for up to a week at a time, day and night. They are then removed, cleaned, and reinserted. But some people cannot tolerate the extended wear. Their eyes become irritated if the contacts are not regularly removed and cleaned. Extended use may be uncomfortable and increases the risk of damaging the eye.
The recommended wearing time for extended-wear lenses has been shortened from 30 days to 7 days because of the increased risk of eye infections. Ideally, you should never sleep with contact lenses on. Most ophthalmologists recommend not sleeping with any type of contact lens in the eyes.
Gas-permeable lenses cost more than conventional hard lenses and are somewhat less durable, but they are more comfortable than conventional hard lenses. Some gas-permeable lenses are designed for extended wear (overnight, up to 7 days), although many eye specialists advise against wearing them for the extended period.
Conventional hard contact lenses are made of a stiff plastic (polymethyl methacrylate, or PMMA), which does not mold to the shape of the eye. They are inexpensive and durable, but they are the least comfortable type of contact lens. Because they reduce the amount of oxygen reaching the cornea, people who wear them are at risk of overwearing syndrome and other problems.
Contact lenses can cause eye problems, such as damage to the cornea or eye infections. It is important to follow the directions for cleaning and wearing these lenses to avoid eye problems.
WebMD Medical Reference from Healthwise