Over 30 million Americans wear contact lenses, according to the American Optometric Association. Unlike glasses, contact lenses move with your eyes so you can enjoy a larger field of vision with fewer distortions. You also don't have to deal with frames hovering in your peripheral vision or external lenses that fog up on cold days or get wet in the rain.
There are many different kinds of contacts, including rigid and flexible, extended wear, disposable and planned replacement lenses. Some can be made as bifocals or in different colors. After a thorough eye exam and consultation with an experienced physician, patients who qualify for contact lenses can discuss which type is right for them. All contact lenses require special care and cleaning. You'll need to make regular follow-up visits to ensure your eyes remain healthy.
The cornea is the clear covering on the front of the eye which bends, or refracts, light rays that focus on the retina in the back of the eye. A certain shape or curvature is required in order for light to focus exactly on the retina, rather than in front of it or behind it.
An improperly curved cornea may be corrected surgically or non-invasively to reduce or eliminate the need for eyeglasses or contact lenses. A thorough eye examination and consultation are necessary before a treatment decision can be made.
Corneal transplantation, or keratoplasty, is recommended when the cornea's curvature is too steep or flat to be treated with other methods, or when extensive damage has occurred due to disease, infection or injury. Common problems that require transplantation are:
Transplantation involves replacing the damaged cornea with a healthy one from a donor (usually through an eye bank). Keratoplasty is a low-risk procedure - it is the most common type of transplant surgery and has the highest success rate.
During the procedure, a circular incision is made in the cornea. A disc of tissue is removed and replaced with healthy tissue; these discs may be thin (lamellar keratoplasty) or as deep as the entire cornea (penetrating keratoplasty), depending on the eye problem. Local or general anesthesia may be used. The entire procedure takes only 30-90 minutes.
Over 140 million people in the U.S. wear eyeglasses, and over 30 million wear contact lenses. Glasses and contact lenses improve vision by adjusting the way the eyes bend and focus light. Ideally, light rays are refracted (bent) as they pass through the cornea so that they focus on the retina in the back of the eye. In a healthy eye, this means that objects can be seen clearly. However, many people’s corneas have a shallow or steep curvature which causes light rays to focus in front of or behind the retina. Objects may then appear blurry at certain distances or at all distances.
Glasses and contact lenses correct these refractive errors. Prescriptions are measured for each eye so patients can enjoy optimal vision clarity, usually 20/20. Eyewear may be used for certain activities, such as reading for farsighted (hyperopic) patients and driving or watching television for nearsighted (myopic) patients, or may be worn at all times.
Regular eye exams test for the development and progression of refractive errors and help your optometrist provide a proper prescription if eyeglasses or contact lenses are needed. Exams are also an invaluable tool in the early detection of eye disease.