This lens implant will take over the focusing function of the eye's original lens. The great majority of cataracts are the result of aging, which causes chemical changes in the natural lens of the eye and interferes with its clarity. However, the age at which a cataract affects someone's vision varies dramatically, from as early as the fifties to as late as the eighties or beyond. Many people with cataracts, in fact, can see quite well, and are not in need of cataract surgery. It is only when the cataract impairs vision to the extent that activities like reading or driving become difficult that surgery may be necessary.
Cataract surgery is almost always an outpatient procedure, done under local anesthesia.
Techniques vary widely, but the eye is always numbed completely with an anesthetic, and often a mild sedative is given to make the person undergoing surgery somewhat drowsy. The surgery is performed under a microscope to provide a magnified view of the eye. A small incision is made in the eye, and the front surface of the cataract is opened to allow access to the clouded tissue inside. The cloudy portion is then removed, leaving the thin clear back surface of the lens in place. This can be done either with a mechanical device called a phacoemulsifier or manually with extracapsular instruments.