A contact lens is a thin disk which floats on the surface of the eye, providing vision correction. With advances in optical technology, most people can now use contact lenses, regardless of the type or extent of their vision problems. This includes patients with astigmatism and those who need bifocal or multifocal lenses. For individuals with certain eye conditions, however, contact lenses are contraindicated.
Types of Contact Lenses
There are several varieties of contact lenses. The distinctive features of each offer a wide range of options.
Soft Contact Lenses
Soft contact lenses are available in three basic types.
Daily-wear soft contact lenses are the most popular type of contacts worn. Made of a flexible plastic polymer, daily-wear lenses are put in each morning and taken out each night. Daily-wear contacts come in many colors and typically last about 1 year.
Extended-wear soft contact lenses can be worn all the time, including while the patient is asleep. Depending on whether a patient has 7-day (standard) or 30-day lenses, the lenses need to be taken out and cleaned once a week or once a month. This is done to give the eyes a rest and reduce the risk of a corneal infection. Extended-wear lenses are made of soft silicone that retains moisture longer than daily-wear contacts. This allows more oxygen to reach the eye, preventing the buildup of bacteria and protein.
Disposable soft lenses are intended to be discarded and replaced after they have been worn for a certain period of time. This makes them even easier to maintain than regular soft contacts. Many disposable lenses are designed for either replacement every morning, every two weeks, or even every month. Daily-wear disposables are worn during waking hours only, while extended-wear disposables can be worn during sleep as well.
Choices of lens type is based upon the doctor's recommendation and the patient's individual needs.
Rigid, gas-permeable contacts offer several advantages over soft lenses. These include:
- Correction of a wider range of vision problems
- Sharper vision than most soft lenses
- More oxygen flow through to the eye, reducing the risk of corneal irritation
- More durability than soft lenses, less prone to deposit buildup
Because they are much harder than flexible contacts, gas-permeable lenses may take some getting used to when they are first worn. They are also more likely than soft lenses to slip off the center of the eye and require adjustment, making them an inconvenient choice for patients who play sports or participate in other vigorous activities. Most patients, however, soon grow accustomed to the feel of gas-permeable lenses and are satisfied with the improvement in vision they offer.
Most ophthalmologists offer a comprehensive array of contact lenses to suit their patients' individual needs. Prescriptions are required for all contact lenses.