Over 24 million people choose contact lenses to correct vision. When used with care and proper supervision, contacts are a safe and effective alternative to eyeglasses. And with today's new lens technology, many people who wear eyeglasses can also successfully wear contacts.
Contacts are thin, clear discs that float on the tear film that coats the cornea, the curved front surface of the eye. Contacts correct the same refractive conditions eyeglasses correct: myopia (nearsightedness), hyperopia (farsightedness) and astigmatism (an oval- rather than round-shaped cornea).
Contact lenses can be made from a number of different plastics. The main distinction among them is whether they are hard or soft. Most contact lens wearers in the United States wear soft lenses. These may be daily wear soft lenses, extended wear lenses or disposable lenses. Toric soft lenses provide a soft lens alternative for people with slight to moderate astigmatism.
Hard lenses are usually not as comfortable as soft lenses and are not as widely used. However, rigid gas permeable lenses provide sharper vision for people with higher refractive errors or larger degrees of astigmatism.
The majority of people can tolerate contact lenses, but there are some exceptions. Conditions that might prevent an individual from successfully wearing contact lenses include dry eye, severe allergies, frequent eye infections, or a dusty and dirty work environment.
Individuals who wear any type of contact lens overnight have a greater chance of developing infections in the cornea. These infections are often due to poor cleaning and lens care.
Extended-Wear Contact Lenses
Some people do not consider wearing contact lenses because they think the required cleaning, disinfecting, storing, and inserting are too much trouble. They may also want the option of occasionally napping or sleeping with their contacts in their eyes.
Extended-wear contacts are designed to appeal to these people. They require less maintenance than daily wear lenses and because they are thinner and allow more oxygen to reach the eyes, they may be left in the eye overnight.
To use extended-wear contact lenses, you must be free of external eye disease, have normal tear function, and be motivated to take care of them.
Infection is the most significant complication of extended-wear contact lens use. They must be removed at least once a week and thoroughly cleaned and disinfected. Many studies show the cornea is put at increased risk of infection by wearing contact lenses overnight. The risk of developing an infection in the cornea is 10-15 times greater for those who wear extended-wear contacts overnight than for those who use daily wear soft lenses. This risk increases with the number of consecutive days the contacts are worn overnight. Infections may range from simple conjunctivitis to blinding endophthalmitis, which is a serious infection that travels through all layers of the eye.
The decision to accept the risks and benefits of extended-wear contacts requires a process of evaluation between you and your doctor. Once you are carefully fit for your contact lenses, follow-up exams with your ophthalmologist to ensure continuing eye health is important. As with any contact lens, extended-wear contacts should be removed at the first sign of redness or discomfort.
Eye Care | Contact Lens
