Your eye works a lot like a camera. Light rays focus through your cornea and lens onto the retina, a layer of light-sensitive cells at the back of the eye. Similar to photographic film, the retina allows the image to be "seen" by the brain.
Cataract is an opacity or clouding of the normally clear lens inside the eye, and is the leading cause of vision loss among adults age 60 or older. Cataracts impair vision, making everyday activities increasingly difficult. The condition can be compared to a window that is frosted or "fogged" with steam. The loss of transparency may be so mild that vision is barely affected, or it can be so severe that no shapes or movements can be detected, only light from dark. Eyeglasses can often correct slight refractive errors caused by early cataracts, but they cannot sharpen your vision with more advanced cataracts.
The most common cause of cataract is aging. Other causes include trauma, medications such as steroids, systemic diseases such as diabetes, and prolonged exposure to ultraviolet light. Cataracts typically develop slowly and progressively, causing a gradual and painless decrease in vision. Other changes you might experience include blurry vision; glare, particularly at night; frequent changes in your eyeglass prescription; a decrease in color intensity; a yellowing of images; and halos.
Cataracts cause varying degrees of visual loss. Some kinds of cataract affect distance vision more than reading vision. For others the opposite applies. Once one has developed, there is no cure except to have the cataract surgically removed. The main indication for cataract surgery is when a person’s visual function no longer meets his or her needs and cataract extraction will provide improved vision. This level of visual impairment is subjective and differs considerably among individuals. It is common for individuals to desire cataract surgery when vision falls below the level of 20/40 eye chart visual acuity since this level of sight is required for unrestricted driving. However, visual acuity can be quite variable depending upon the testing conditions, test distance, and type of cataract. Therefore, it may be difficult to appreciate the impact of a cataract on an individual’s vision especially when he or she can see better than 20/40.
There has been a steady evolution in cataract treatment since around 1990, which translates to added patient benefits, including improved visual outcomes and faster recoveries. Phacoemulsification is a relatively quick outpatient procedure that removes the cataract with little discomfort and a rapid return to normal activities. It requires a tiny incision and breaks up the cataract with ultrasonic energy. Next, a soft, flexible synthetic intraocular lens (IOL) is inserted into the lens capsule of the eye to replace the refractive power of the lens that was removed. In most cases, the incision is so small that no stitches are needed and the eye heals rapidly with little or no discomfort. Drops are used after cataract surgery, and the patient is asked to refrain from swimming or water activity for two weeks.
Cataract surgery is considered one of the most popular and highly successful surgical procedures. In fact, a study by the American Society of Cataract and Refractive Surgery reported that more than 98 percent of cataract patients had their vision successfully improved following surgery. Many patients report vision that seems even better than before they developed cataracts. Once removed, cataracts will not recur; however, some individuals will develop a cloudiness to the lens capsule that has been left in place, and this can be treated by a painless office laser procedure with rapid vision restoration.
For more information, visit www.geteyesmart.org