Types of Contact Lenses

Hard contact lenses

Hard lenses were the first contact lenses available. Although they are not often prescribed now, they had several advantages. They were easy to put in and take out and easy to care for. They did not cost very much and lasted a long time. For many people, they provided very good vision.

However, the original hard lenses were often uncomfortable during the first week or two of wear. Also, they did not allow much oxygen to reach the cornea. (The cornea is the clear outer layer on the front of the eyeball.) Not getting enough oxygen can damage the cornea. Gas permeable lenses have the same benefits but allow more oxygen to get to the cornea.

Gas permeable contact lenses

Gas permeable lenses are made of a type of plastic that allows oxygen to reach the cornea. They are easier to care for than soft contacts. They are also easier to insert and remove. Gas permeable contacts can correct many vision problems related to abnormal cornea shapes. At first, most people need a few days to get used to them. Some of the newest gas permeable lenses are approved for extended wear. Most contacts should not be worn during sleep. Follow your eye care provider's advice about how long you can leave in extended wear lenses.

Soft contact lenses

Soft contacts are lenses made of flexible plastic that absorbs liquids. Unlike gas permeable or hard lenses, they usually do not cause discomfort when you first wear them. They can correct many vision problems due to abnormal corneal shapes. However, they sometimes do not give as good of vision as gas permeable lenses.

Putting soft contacts in and taking them out may take a little practice. Also, soft contacts must be cleaned and sterilized very carefully. Daily-wear soft lenses are sterilized nightly. Extended-wear soft lenses are sterilized each time you remove them.

Soft lenses cost more than gas permeable lenses. They may wear out and need to be replaced more often. You may have more problems with allergies if you wear soft lenses. Also, you may develop eye infections more often, especially if you wear your contact lenses while you sleep. An eye infection called a corneal ulcer can be serious and possibly cause a loss of sight. If you have dry eyes, you may not be able to wear soft contacts.

Regular soft lenses do not correct astigmatism (vision problems caused by an uneven cornea) as well as gas permeable lenses do. However, special soft lenses called toric lenses are available for people with astigmatism.

Disposable contact lenses

Disposable contact lenses are soft contact lenses that are replaced frequently. Some extended wear disposable contacts are worn for 1 week and then thrown away. Some are sterilized after 1 week of wear, worn for a second week, and then thrown away. Daily wear disposable lenses are removed and sterilized nightly for 2 weeks and then thrown out. Never wear your lenses longer than recommended because this can result in a severe infection.

The disposable contact lenses are convenient and they provide the clear vision and comfort often associated with new lenses. They may help people who are allergic to contact lens solutions or protein deposits on their lenses. The disadvantages of disposable contacts are that they cost more than other contact lenses.

Bifocal contact lenses

Bifocal contact lenses have both your distance prescription and your reading prescription in each lens. They are available as gas permeable or soft lenses, and as daily wear or extended wear types. However, not everybody likes bifocal contacts so a trial period is usually recommended.