Contact lenses are small plastic or silicone discs shaped to correct refractive errors.
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 hard and soft contact lenses are available.
What To Expect
With most hard contact lenses, there will be a 2- to 4-week break-in period during which you wear the lenses for increasingly longer periods of time each day. Soft contact lenses usually take less time to break in.
The care of contact lenses varies according to the type of lens. Care may range from minimal (disposable extended-wear soft lenses) to extensive (conventional soft lenses). It is important to follow directions for lens care carefully to avoid vision-threatening complications. If you have a hard time following the cleaning steps, tell your eye care professional. You may be able to simplify the cleaning steps. Or you may want to switch to disposable lenses.
Why It Is Done
Contact lenses can correct nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. Lenses that correct astigmatism are called toric lenses. They may need to be custom-made and may cost more than ordinary contact lenses.
Contact lenses may be used by people who have had cataract surgery and couldn't have an artificial lens implanted in the eye. They may also be used to treat eye diseases, such as keratoconus or damage to the cornea caused by injury or infection.
Most people choose to wear contacts because of the convenience and because they prefer the way they look without eyeglasses.
Multifocal contact lenses have been developed for people who have both nearsightedness and presbyopia. Multifocal lenses provide correction for both near and distance vision on each lens.
If multifocal contact lenses will not work for you, your doctor may recommend monovision. With monovision, you wear a contact lens that corrects for near vision in one eye and a lens that corrects for distance vision in the other eye. Many people who try monovision can adjust to it. Monovision has some drawbacks, though. Each eye must work more independently, making good binocular vision difficult, which can cause problems with depth perception. You may have to adjust your gaze more often to allow one eye or the other to see properly.
In other cases, your doctor may recommend using reading glasses in combination with contact lenses that correct for distance vision.
People who are generally well-suited to wearing contact lenses (hard or soft) include:
- People who have a lot of trouble seeing things at a distance and need vision correction all the time. People who wear eyeglasses only part of the time are less likely to wear contacts successfully.
- Those with strong motivation. You have to be willing to tolerate minor discomfort during the break-in period and to learn and use proper methods of storing and handling your lenses.
People who perform work or play sports in which glasses are inconvenient or dangerous often choose contacts over glasses.
Contact lenses may not be a good choice if you:
- Are not able or are not willing to care for the lenses properly.
- Would have a hard time handling the lenses (for example, if you have severe arthritis in your hands or another problem that would make it hard for you to insert, remove, and clean the lenses).
- Have certain medical conditions such as uncontrolled diabetes or hyperthyroidism. Allergies, asthma, and other chronic respiratory disorders may make it difficult to wear contacts.
- Have dry eyes or problems with the cornea. People who have Sjögren's syndrome (a condition that causes a lack of tears and dry eyes) often are not able to wear contacts. People who have chronic or recurrent infections or sores on the cornea cannot wear contact lenses.
- Have a job that exposes you to particles, chemical fumes, or other vapors that may be absorbed by or stick to the lenses (such as dust and dirt, paint, spray chemicals, or hair spray).
Infants and children
Infants and children usually do not wear contact lenses, except to treat some medical conditions. Many teenagers wear contacts. But they and their parents must accept the need for frequent changes in the prescription until the eyes stop changing in the late teens or early 20s.
How Well It Works
Some types work better than others to correct specific problems. For example:
- Rigid gas-permeable lenses may be the best choice for people who have astigmatism that's quite high or not normal.
- Some people cannot tolerate hard lenses. Soft lenses that correct both nearsightedness and astigmatism are available. Soft contact lenses tend to be more comfortable than hard lenses, but hard lenses usually provide sharper vision.
- Some people may choose good (rather than optimal) vision correction in exchange for greater comfort. People who have severe nearsightedness or both nearsightedness and astigmatism may get the best vision correction from gas-permeable lenses. But these people may have satisfactory correction with soft lenses, which are typically more comfortable.
Minor but bothersome side effects of contact lenses are common. But the overall risk of infection and other vision-threatening complications is low.
Problems sometimes caused by wearing contact lenses include:
- Dry eyes.
- Problems with the cornea, such as swelling and hazy vision caused by decreased oxygen to the cornea (hypoxia), corneal scratches and scrapes, changes in the cornea's shape, or infection of the cornea.
- Allergic reactions to contact lens solution.
- Deposits on the lenses, which may make the lenses less comfortable and increase the risk of infection (deposits are rare with hard lenses).
- Eye inflammation.
- Eyelid inflammation. Inflammatory bumps can form under the eyelid, making it uncomfortable to wear contacts.
Some problems are more common with certain types of lenses. You may be able to avoid some problems by cleaning your lenses more often, not wearing your lenses overnight or, in some cases, changing the type of lenses you wear.