Perhaps one of the most commonly misunderstood diseases related to the eyes is cataracts. This is the clouding up of the eye's natural lens, which lies behind the iris and the pupil. This lens works just like a camera lens, focusing light onto the retina, which is located at the back of the eye. The lens can also adjust the eye's focus, letting you see things clearly both far away and up close.
Cataracts usually start out small, and have little effect on your vision. You may notice that your vision is slightly blurred, similar to looking through a cloudy piece of glass or viewing an impressionist painting. A cataract can make light from the sun or a lamp seems too bright or glaring, or you may notice when you drive at night that the oncoming headlights cause more glare than usual. Also, colors may not appear as bright as they did at one time. The type of cataract you have affects exactly which symptoms you experience and how soon they will occur.
The lens is mostly made up of protein and water. The protein is arranged in a way that keeps the lens clear and at the same time lets light pass through it. As we all age, some of the protein may clump together and start to cloud small areas of the lens. Over time, this cataract may grow larger and cloud more of the lens, which makes it much harder to see.
A cataract is classified as one of three types: cortical, nuclear, or subcapsular. But don’t let the big names scare you: a nuclear cataract is usually seen when it forms. A cataract like this forms in the nucleus (the center of the lens), and is due to natural aging changes. When a nuclear cataract is first developing, it can bring a temporary improvement in your near vision, called "second sight". Unfortunately, the improved vision does not last long and will disappear as the cataract worsens. A cortical cataract forms in the lens cortex and gradually extends its spokes from the outside of the lens to the center. Many diabetic people develop cortical cataracts. Subcapular cataracts begin at the back of the lens. Meanwhile, a subcapsular cataract may not produce any symptoms until it's very well developed. People with diabetes, retinis pigmentosa, high farsightedness, or those taking high doses of steroids, may develop a subcapular cataract.
It’s not quite clear why the eye's lens changes as we age and form cataracts. Researchers are gradually identifying factors that may cause cataracts, and information that may help prevent them. Many studies suggest that exposure to ultraviolet light is associated with cataracts. This is why eye care practitioners recommend wearing sunglasses and a wide-brimmed hat to lessen your exposure. Other studies suggest that people with diabetes are at risk for developing a cataract. The same goes for users of diuretics, steroids, and major tranquilizers but more studies are needed to distinguish the effect of the disease from the consequences of the drugs themselves.
Some eye care practitioners believe a diet of high antioxidants, such as beta-carotene (Vitamin A), selenium, and Vitamins C and E, may prevent cataracts. Eating large amounts of salt may increase your risk. Other risk factors include air pollution, cigarette smoke, and heavy alcohol consumption. There was a small study that found exposure to lead to be a risk factor as well, but larger studies are needed to confirm whether or not lead can definitely put you at risk
When symptoms begin to appear, you might be able to improve your vision for a while by using strong bifocals, magnification, appropriate lighting, new glasses, or other visual aids. Many people consider poor vision a predictable fact of aging, but cataract surgery is a simple and relatively painless procedure to regain vision. Cataract surgery is usually very successful in restoring vision. In fact, this surgery is the most frequently performed surgery in the United States, with over 1.5 million procedures done each year. Nine out of the ten people who have cataract surgery, regain very good vision to somewhere in between 20/20 and 20/40.
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