The cornea is the transparent front outer layer of the eye that covers the pupil and the iris. The cornea accounts for approximately two thirds of the eye’s total optical power, but unlike the adjustable curvature of the eye’s lens, the amplification provided by the cornea is fixed, or constant. The cornea has multiple layers, and typically holds a uniform shape. But various conditions can affect the shape of your corneas and, consequently, your vision.

    Astigmatism is an optical defect that causes blurred vision due to the eye’s inability to properly focus an image on the retina. This impairment may be due to a number of factors, including an irregular shape of the cornea. Usually, in eyes with astigmatism, the corneas are shaped somewhat like an American football, which makes prolonged focusing of the lenses difficult or painful. Mild cases of astigmatism can sometimes be corrected with glasses, but sometimes contact lenses are necessary. Refractive surgery is also a potential solution.

    Another condition that affects the cornea is called keratoconus: a degenerative affliction in which the normally round corneal layer thins and develops into a conical bulge. While the cause of keratoconus has not been scientifically proven, some studies suggest that the weakening of corneal tissue is linked to an imbalance of enzymes. Other research indicates a correlation between keratoconus and frequent physical contact with the eyes such as eye rubbing, or a history of poorly fitting contact lenses. Although keratoconus is far less common than astigmatism, its symptoms are much more severe, and cannot be corrected by eyeglasses. It is not uncommon for individuals with keratoconus to correct their vision with scleral lenses, which have roughly the same diameter as a quarter, and rest on the less-sensitive parts of the eye.

    When conventional methods are unable to compensate for misshapen corneas, however, corneal transplant surgery may be necessary. During corneal transplant surgery, the surgeon removes the central portion of the damaged or cloudy cornea and replaces it with a clear cornea, usually donated from an eye bank. A trephine, an instrument similar to a cookie cutter, is used to remove the cloudy cornea. The surgeon then places the new cornea into the opening and sews it shut with a fine thread. The process may seem painful and invasive, but the procedure is perfectly safe, and has a very high rate of success in the United States.

    Your cornea is a vital part of your vision, and the shape and health of your corneas should be routinely monitored. If you suspect that you may have an issue with the size of shape of your cornea, contact Silverstein Eye Care Centers. Call us today at (816) 358-3600 or request an appointment online. We can serve you at our convenient location in Independence/Kansas City.

    Posted August 20, 2015 by Silverstein Eye Centers
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