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Free Laser Vision Screening
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Light is focused, or refracted, by the cornea, the clear front window of the eye, and the lens, a clear tissue that sits behind the colored part of your eye. Your vision is clear if the cornea and lens focus the image precisely on the retina, a layer of light sensitive cells that lines the back of the eye. When images are not properly focused onto the retina, but can be properly focused with glasses or a contact lens, you have a refractive error. When images are focused in front of the retina, distant objects appear blurry, but near ones appear sharper. This is called myopia or nearsightedness. When images are focused beyond the retina, nearby objects appear blurrier than distant objects. This condition is called hyperopia or farsightedness. If your cornea has unequal curves, images are distorted because light focuses on more than one point on the retina. This is known as astigmatism. Until recently, glasses and contact lenses were the only options available to correct refractive errors. Refractive surgery is now an option for some people with myopia (nearsightedness), hyperopia (farsightedness) and astigmatism. Refractive solutionsGlasses and contact lenses correct refractive errors by compensating for the wrong refractive power of the cornea and lens. Refractive surgery improves vision by changing the shape of the cornea. Common refractive surgery procedures include:
Radial keratotomy reduces myopia by changing the curvature of the cornea over the pupil. While this procedure was used frequently, its' shortcomings have been surpassed by other refractive procedures. A similar technique, astigmatic keratotomy (AK), is used to reduce astigmatism. In this procedure, the surgeon makes incisions in a curved rather than a radial pattern. AK does not have the shortcomings that RK had and is still widely used today. Complications at the time of surgery are rare but can be serious. After RK and AK, the cornea heals slowly, and concerns remain about the side effects of this delayed corneal healing. There may be:
Temporary pain. Photorefractive keratectomy and LASER assisted in-sity keratomileusis (PRK and LASIK)The excimer laser is used to reduce myopia in a procedure called photorefractive
keratectomy (PRK). Using an invisible, high-energy light, the laser precisely sculpts the
cornea. No surgical blades are used in PRK. Because the laser disrupts the center or optical zone of your cornea, hazy vision is a common but temporary side effect of PRK. It usually improves within several months. There are several thousand people in the United States who have had excimer laser surgery through research studies authorized and reviewed by the Food and Drug Administration (FDA). In a recent study conducted by the FDA, 95% of the operated eyes were corrected to 20/40 or better. The study also showed that up to 63% of the patients experienced blurry vision after surgery, and 10% of the patients reported haloes around lights. These symptoms subsided in most patients over a period of six months. LASIK is a modified version of PRK where the central skin covering of the cornea is preserved by using a specialized knife. A thin flap is created and folded back. The LASER is applied to the bed of the flap, and after lasering is completed, the flap is returned to its normal position. LASIK is superior because it allows for a more rapid recovery of vision, and less doctor visits. It is, however, a technically more difficult procedure. Complications at the time of surgery are rare but can be serious. After PRK and LASIK there may be:
Automated lamellar keratoplasty (ALK), Laser Thermal Keratoplasty (LTK), and Intracorneal Ring Segments (Intacs).These are less-widely used refractive procedures that are much more specialized and may not be appropriate for most patients. Specifically, ALK is only used for very nearsighted people, LTK is used for minimally farsighted people, and Intacs are used for minimally nearsighted people. Your ophthalmologist can discuss these procedures with you. Should you consider refractive surgery?You might consider refractive surgery if you:
While refractive surgery does offer many people an alternative to dependence on glasses
or contact lenses, it's certainly not for everyone. You may not be a good candidate for
refractive surgery if you are generally happy and comfortable with your current glasses or
contacts and you are not willing to accept the somewhat variable outcome or the risks of
currently available procedures. Even after refractive surgery, some people still need to
wear glasses or contacts in some situations. |
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