Cataract

1. Cataract Tom Avenoso

2. How Cataracts Affect Vision? • On the left, a normal lens receives light and focuses it on the retina. On the right, a cataract blocks some light from reaching the lens and distorts the light being focused on the retina. • Cataracts usually develop without any

3. How they form? • Cataracts usually develop without any apparent cause; however, they can result from injury to the eye, prolonged exposure to certain drugs (such as corticosteroids) or to x-rays (such as with radiation therapy to the eye), inflammatory and infectious eye diseases, and as a complication of diseases such as diabetes. • Cataracts also seem to be more common in people with dark eyes, those who have had prolonged exposure to direct sunlight, those with poor nutrition, and smokers. People who have had a cataract in one eye are more likely to develop one later in the other eye.

4. Symptoms • all light entering the eye passes through the lens, any clouding of the lens that blocks, distorts, or diffuses light can cause poor vision. The first symptom of a cataract is usually blurred vision. Glare and halos and, less commonly, double vision can also be early symptoms of cataracts. A person may also notice that colors seem more yellow and less vibrant. Reading may become more difficult because of a worsening ability to distinguish between the light and dark of printed letters on a page.

5. Symptoms • How much vision is changed by a cataract depends on the intensity of light entering the eye and on the location of the cataract. In bright light, the pupil constricts and narrows the pathway through which light enters the eye, and light cannot easily pass around a cataract that is centrally located (nuclear cataract). In dim light, the pupil dilates; bright lights, such as oncoming headlights, are scattered by the edge of the cataract, causing halos and glare, which may be especially disturbing during night driving. People with cataracts who take drugs that constrict their pupils (certain glaucoma eye drops, for example) may also have greater vision loss.

6. Treatment • Until vision is considerably impaired, eyeglasses and contact lenses may improve a person's vision. Wearing sunglasses in bright light and using lamps that provide over-the-shoulder lighting may decrease glare and aid vision. Rarely, drugs that keep the pupil dilated may be used to help vision if the cataract is located in the center of the lens. • The only treatment that provides a cure for cataracts is surgery; there are no eye drops or drugs that will make cataracts go away. Occasionally, cataracts will cause changes (such as swelling of the cataract or glaucoma) that lead doctors to recommend the cataract be removed quickly. However, most times people should have surgery only when their vision is so impaired by cataracts that they feel unsafe, uncomfortable, or unable to perform daily tasks. There is no advantage to having cataracts removed before then.

7. Surgery • Cataract surgery can be performed on a person of any age and is generally safe even for people with illnesses such as heart disease and diabetes. Usually, the doctor makes a small incision in the eye and removes the cataract by breaking it up with ultrasound and taking out the pieces (phacoemulsification). When all the cataract pieces have been removed, the surgeon replaces the cataract with an artificial lens (intraocular lens). The intraocular lens cannot always be safely placed, however; when this is the case, people must wear thick eyeglasses or contact lenses after the cataract has been removed.

9. Eye with Cataract • This is a eye with cataract you can tell because of the cloudy spot in the lens