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Contact lenses
Contact lenses are small plastic or silicone discs shaped to correct an eyesight problem such as nearsightedness, farsightedness, presbyopia, or astigmatism. These are called refractive errors. They may also be used by people who have had surgery for cataracts.
After your doctor tests your vision, he or she will write a prescription for the lens you need. Your prescription may change over time.
Contacts are placed directly on the eye, where they float on a film of tears in front of the cornea. Correct design and fitting of the lenses are essential for comfort, safety, and accurate correction.
Improvements in contact lenses have made them more comfortable and easier to wear. Millions of people wear contact lenses, and most wear soft lenses. For these people, contact lenses offer a relatively safe and effective way of correcting vision problems.
Several types of contact lenses are available to correct nearsightedness. Contact lenses are needed after cataract surgery if an artificial lens cannot be implanted in the eye.
Hard (rigid) lenses
- Conventional hard (polymethyl methacrylate, or PMMA) lenses are made of a stiff plastic. They correct vision with no distortion, but they are the least comfortable type of contact lens.
- Rigid gas-permeable (RGP) lenses are more comfortable than conventional hard lenses. Some gas-permeable lenses are designed to be worn overnight and for up to 7 days.
Soft lenses
- Daily-wear lenses are removed and cleaned at night and reinserted in the morning. You'll need to buy new ones at least once a year.
- Extended-wear lenses can be worn for up to a week at a time, day and night. But extended use may be uncomfortable, and it increases the risk of damaging the eye.
- Disposable lenses (daily and extended-wear) may be worn for up to several weeks and then discarded.
| By: | Healthwise Staff | Last Revised: July 6, 2009 |
| Medical Review: | Kathleen Romito, MD - Family Medicine Christopher J. Rudnisky - Ophthalmology | |
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