Daily wear contact lenses can be soft or rigid contact lenses made of different types of plastic, depending on the specific type of lens. Daily wear lenses are to be worn for periods of less than 24 hours at a time, and should be removed each night before the wearer goes to sleep. Lenses generally need to be replaced annually or biannually.
Extended wear contact lenses
Extended wear contact lenses are usually soft contact lenses, but are designed to be worn for 24 hours or more at a time. Some lenses are FDA approved for up to 30 days of continuous wear, but most doctors recommend removing and cleaning the lenses at least weekly. Extended wear lenses have replacement schedules that vary significantly by the specific type of lens and length of continuous wear.
Disposable contact lenses
Disposable contact lenses are soft contact lenses, either daily wear or extended wear, that are replaced on a 7 to 30 day cycle. Wearers generally purchase a supply of disposable lenses that will last six months to one year.
Hard contact lenses
Hard contact lenses are made from a rigid plastic resin, polymethylemethacrylate (PMMA). The lenses are more durable and easier to handle than soft contact lenses, but many people may find them uncomfortable. PMMA does not absorb water, and does not allow for the transmission of oxygen through the lens to the eye. Hard contact lenses should be removed daily.
Rigid gas permeable contact lenses
Rigid gas permeable (RGP) contact lenses are made of a non-absorbent material that is oxygen permeable. RGP lenses are durable and easy to handle like hard contact lenses, but more comfortable to wear, though usually not as comfortable as soft contact lenses. Most RGP lenses are used for daily wear, but some lenses can be worn for extended periods of time.
Medically necessary contact lenses
Following certain surgeries, soft contact lenses are sometimes prescribed to act as a replacement for the front covering of the eye that has been removed or disturbed. These contact lens prescriptions are medically necessary, and are generally addressed differently than elective contact lenses in managed vision care policies. Medically necessary contact lenses can also be prescribed for the treatment of certain eye diseases, including keratonocus.
Toric lenses
Toric lenses are either hard or soft contact lenses used to treat astigmatism, which cannot be corrected with traditional spherical contact lenses.
Tinted contact lenses
Many soft and disposable contact lenses have a visibility tint, usually bluish, that makes them easier to see. This visibility tint makes the lenses easier to handle and easier to find if the wearer drops them. There is generally no additional charge for lenses with a visibility tint. Contact lenses can also be tinted to change or enhance the color of the wearer’s eye. The lenses are generally made with a clear center so that the wearer’s perception of color is not affected. Since these lenses are more complicated to manufacture, they are generally more expensive than clear contact lenses.