www.fda.gov//fdac/features/1998/498_eye.html
Food and Drug Administration This article originally appeared in the July-August 1998 issue of the FDA Consumer Magazine and contains revisions made in August 1998 and April 1999. Without her contact lenses she couldn't distinguish people, the scenes on television, the stars at night, and, generally, the world at large. Then, in March 1998, the 49-year-old California resident had eye surgery, and all that changed. Goldstein underwent refractive eye surgery, an elective procedure intended to correct common eye disorders, known as refractive errors, such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (distorted vision). Although there are several types of surgical techniques being performed today to correct refractive errors, laser refractive correction is fast becoming the most technologically advanced method available, according to the American Academy of Ophthalmology in San Francisco. Doctors say it allows for an unparalleled degree of precision and predictability. With that approval, the agency also restricted use of the laser to practitioners trained both in laser refractive surgery and in the calibration and operation of the laser. Currently, the excimer laser has been approved for use in a procedure called photorefractive keratectomy (PRK), and, as of November 1998, for a procedure called laser in situ Keratomileusis (LASIK). Precision Surgery PRK is an outpatient procedure generally performed with local anesthetic eye drops. This type of refractive surgery gently reshapes the cornea by removing microscopic amounts of tissue from the outer surface with a cool, computer-controlled ultraviolet beam of light. The beam is so precise it can cut notches in a strand of human hair without breaking it, and each pulse can remove 39 millionths of an inch of tissue in 12 billionths of a second. The procedure itself takes only a few minutes, and patients are typically back to daily routines in one to three days. Before the procedure begins, the patient's eye is measured to determine the degree of visual problem, and a map of the eye's surface is constructed. The required corneal change is calculated based on this information, and then entered into the laser's computer. Since 1995, a limited number of laser systems has been approved by FDA to treat various refractive errors, both with PRK and LASIK. According to FDA's Center for Devices and Radiological Health, clinical studies showed that about 5 percent of patients continued to always need glasses following PRK for distance, and up to 15 percent needed glasses occasionally, such as when driving. In addition, many patients experienced mild corneal haze following surgery, which is part of the normal healing process. The haze appeared to have little or no effect on final vision, and could only be seen by a doctor with a microscope. Some patients experienced glare and halos around lights. These conditions, however, diminished or disappeared in most patients in six months. For about 5 percent of patients, however, best-corrected vision without corrective lenses was slightly worse after surgery than before. In view of these findings, FDA and the Federal Trade Commission (which oversees advertising) issued a letter to the eye-care community in May 1996 warning that unrealistic advertising claims, such as "throw away your eyeglasses," and unsubstantiated claims about success rates could be misleading to consumers. The surgeon uses a knife called a microkeratome to cut a flap of corneal tissue, removes the targeted tissue beneath it with the laser, and then replaces the flap. But most uses are considered "off label" and are not regulated by FDA. They also say that there is generally a faster recovery time after LASIK than after PRK. In addition, LASIK patients can see well enough to drive immediately and have good vision within a week. After studying the options, Goldstein first decided on the LASIK procedure, but was surprised to learn that her doctor advised against it. Although routinely performing laser eye surgery, he still encourages a small percentage of his low to moderately nearsighted patients to undergo radial keratotomy, or RK, an earlier refractive correction procedure that does not require the excimer laser. With RK, incisions are made in a "radial" pattern along the outer portion of the cornea using a hand-held blade. These incisions are designed to help flatten the curvature of the cornea, thereby allowing light rays entering the eye to properly focus on the retina. The number and length of the incisions determines the degree of correction attained. Conversely, Crawford says that although he will mention RK as an option to his patients considering eye surgery, he is not in favor of this method. He says studies indicate that incisions made during this procedure, which penetrate approximately 90 percent of the cornea, appear to weaken the structure of the eye. Also, once you've had RK done you can't repeat it or have PRK done. For some, like Goldstein, laser surgery has been the ultimate freedom from the everyday hassles of contact lenses, and a second chance at having normal eyesight. Pregnant women should not have refractive surgery of any kind because the refraction of the eye may change during pregnancy. Looking Ahead At present, a number of other lasers for eye surgery are currently being tested in FDA-sanctioned studies to determine their safety and effectiveness. Investigational Device Exemptions (IDEs) filed with FDA allow for clinical studies involving the excimer laser and the correction of farsightedness. The IDE process is designed to investigate the safety and effectiveness of a device, or a new procedure with an already approved device, either to obtain information for publication or to generate the data needed to obtain marketing approval from FDA. You may be a good candidate for laser eye surgery if you: * are at least 21 years of age for a Summit laser or 18 years of age for a VISX laser, since the eyes are still growing to this point * have healthy eyes that are free from retinal problems, corneal scars, and any eye disease (refractive errors are considered eye disorders, not diseases) * have mild to moderate myopia (nearsightedness) within the range of treatment (see your doctor to determine your range) * have a way to pay for the treatment since laser procedures are costly and probably not covered by health insurance policies * are fully informed about the risks and benefits of laser surgery compared with other available treatments. Frequently Asked Questions About Laser Eye Surgery Is it painful? There is little if any discomfort during surgery because the cornea and eye are anesthetized by drops. Most people can return to work one to three days following surgery, but a rule of thumb is to wait until you feel up to it. Most return to normal activities as soon as the day after surgery. The most common side effects are a halo effect and some glare at night around lights.
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