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Correcting or Improving Vision Problems
Clear vision depends on how well the cornea and lens permit light rays to fall onto the retina. Light rays must be refracted (bent) to focus on the retina. The retina is the light-sensitive nerve layer that lines the back of the eye, which creates impulses from the light rays that are sent through the optic nerve to the brain. If the cornea or eye shape is abnormal, vision can become blurry because light does not fall properly on the retina. Called a refractive error, an abnormal cornea shape can often be corrected by refractive eye surgery, which, in turn, corrects the vision problem. Refractive errors can include myopia (nearsightedness), hyperopia (farsightedness), astigmatism (an irregularly shaped cornea which causes blurring), and presbyopia (similar to hyperopia, a condition which causes the lens to harden). The goal of most refractive eye surgeries is to reduce or eliminate a person’s dependency on eyeglasses or contact lenses. Refractive eye surgery is not for everyone. One type of surgery may be more suitable for one person than another. Always consult your physician for a diagnosis and to discuss which type of surgery, if any, may be appropriate for you. In the Northwest, Casey Vision Correction Center has been an innovator in laser vision correction surgery. The internationally recognized Casey team performed the first PRK in the Northwest in December 1994 and the first LASIK in the area in October 1996. Learn more about Casey Vision Correction Center. There are several types of corrective surgical procedures for refractive errors, including, but not limited to laser in-situ keratomileusis surgery (LASIK) and photorefractive keratectomy (PRK). What is LASIK surgery? LASIK, or laser in-situ keratomileusis, surgery is used to correct nearsightedness. When a person is nearsighted (myopic), his or her eye is too long or the cornea is too steep, resulting in too much focusing power. The light rays entering the eye come in focus before hitting the retina, resulting in blurry vision when looking in the distance. The procedure, which should be performed by a skilled eye surgeon, involves reshaping the cornea using an excimer laser. LASIK is replacing many of the other refractive eye surgery techniques. What is an excimer laser? An excimer laser is controlled by a computer, allowing for precise cutting of the cornea. The excimer laser emits an ultraviolet, non-thermal (cold), invisible beam, which is so precise it can remove 39 millionth of an inch of tissue in 12 billionth of a second, according to the US Food and Drug Administration (FDA). The excimer laser has been used in photorefractive keratectomy (PRK) and was approved for use in LASIK surgery by the FDA in 1998. How is LASIK surgery performed? Although each procedure varies slightly, in general, LASIK surgery involves using a computer-controlled excimer laser (a cold, ultraviolet laser) and a microkeratome (a surgical instrument). With these instruments, the surgeon cuts a flap in the center of the cornea to remove a thin layer of tissue. By removing the tissue, the cornea flattens, reducing the myopia. The flap, which is replaced without using sutures, adheres back to the cornea within minutes. Recovery after LASIK surgery In most cases, recovery from LASIK surgery is fast and involves minimal discomfort. Mild pain relievers may be recommended by your surgeon to relieve discomfort during the first day after surgery. Patients typically take eyedrops for a week after the procedure. Possible side effects of LASIK surgery Generally, LASIK has a high success rate. However, side effects do occur. The following are the most common side effects and complications. Each individual may experience side effects differently. Side effects may include:
For most candidates, LASIK surgery usually involves little pain and recovery is rapid. Other benefits may include:
What is photorefractive keratectomy (PRK) surgery? Photorefractive keratectomy, or PRK, uses the same excimer laser used in LASIK surgery and is performed to reshape the cornea in an attempt to correct mild to moderate myopia (nearsightedness). According to the US Food and Drug Administration (FDA), PRK has a 95 percent success rate. Only about 15 percent of patients need glasses, occasionally, following surgery. How is PRK surgery performed? Although each procedure varies slightly, in general, PRK surgery involves an excimer laser beam reshaping the cornea by removing microscopic amounts of tissue from the outer surface. The procedure, which generally only takes a few minutes, uses a computer which maps the eye’s surface and calculates the required corneal change. Possible side effects of PRK surgery Generally, PRK surgery has a high success rate. However, side effects do occur. Because the corneal surface is cut, it takes several weeks to heal. In addition, there is some eye discomfort following the surgery that may last for several weeks. The following are the most common side effects and complications. Each individual may experience side effects differently. Side effects may include:
According to the US Food and Drug Administration (FDA), potential candidates for corrective laser eye surgery must meet the following criteria. However, it is advised that potential candidates consult his/her physician before undergoing any type of corrective eye surgery. The criteria include:
How to prepare for refractive eye surgery Most refractive eye surgeries are performed on an outpatient basis, with most procedures lasting less than an hour. In preparation for surgery, you may be asked to:
Although each procedure varies slightly, in general, refractive eye surgery involves minimal discomfort. The eye is usually numbed with eye drops prior to surgery. While in surgery, you may also:
Recovering from surgery Recovery times vary depending on the surgery, but can last anywhere from a couple of days to a couple of months. The following are some common symptoms following surgery. However, each individual may experience symptoms differently. Symptoms following surgery may include:
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