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LASIK Risks and Complications Apr 2, 2008
Like any surgery, LASIK and other vision correction procedures have some risks and possible complications. But since the first laser vision correction surgery was performed in the United States in 1988, serious complications from LASIK, PRK and other laser procedures have been uncommon, and serious vision loss from the procedures has been rare.
How frequently do LASIK complications occur? Advances in refractive surgery technology and techniques have improved outcomes and decreased risks and complications associated with LASIK. Experienced LASIK surgeons report that serious complications can be held well below 1% if surgical candidates are carefully screened and selected. During your LASIK consultation, be sure to mention any health problems you have, as certain conditions may increase your risk of complications after refractive surgery. As part of your LASIK consultation and pre-operative exam, your doctor will thoroughly evaluate the health of your eyes to rule out chronic dry eye, thin corneas, unusually large pupils and other factors that might affect your LASIK outcome. Prior to LASIK, you will be asked to sign a consent form, which will mention risks and possible complications. Read this document carefully. Your signature acknowledges that you are choosing to have LASIK with a full understanding that, even in the best of circumstances, there is a chance something unintended could occur. Though most complications or undesired outcomes can be successfully managed, there is still some risk that your vision after LASIK will be less clear than it was with glasses or contact lenses prior to the procedure – a condition called loss of best corrected visual acuity (BCVA) – and that this condition may be permanent. Also, you may experience permanent dry eye symptoms after LASIK that you didn’t have prior to the procedure. Be sure to discuss these risks with your surgeon prior to your decision to have LASIK or other laser vision correction surgery. Potential LASIK complications It’s difficult to accurately report the risk of LASIK complications. There is no centralized organization or agency that collects these data, so most statistics are gathered by independent surgeons or researchers. Also, the technology and techniques used in refractive surgery are constantly improving, so data gathered about LASIK performed in 2005 may overestimate the risk of complications in 2008, when newer surgical equipment or techniques may be employed. With this in mind, here is a list of some of the most common LASIK complications, in approximate order of how frequently they occur: Dry eye Nerves within the cornea (the clear front part of the eye that’s reshaped by the laser) play a role in your body’s ability to produce tears and keep your eyes moist and comfortable. Some of these nerves are damaged during LASIK, and this can cause dry eye problems. Though some corneal nerves regenerate over time and dry eye symptoms usually decrease within a few weeks to a few months after LASIK, some patients will have persistent dry eye problems. Symptoms of dry eye can include discomfort, sensitivity to light, and blurred vision. In one recent study, 20% of LASIK patients experienced chronic dry eye that persisted for six months or more after surgery. (1) A high degree of pre-operative nearsightedness appears to be a risk factor for dry eye after LASIK. Treatment for dry eye usually consists of frequent use of artificial tears. For more severe cases, medicated eye drops can often help your body increase tear flow. Also, tiny silicone plugs inserted in the drainage ducts of the eyelids can keep more tears on the eyes and relieve dry eye symptoms. Nutritional supplements like flaxseed oil have also shown to be helpful in relieving dry eye. Due to the increased risk of dry eye problems after LASIK, people who have pre-existing dry eye should have this condition addressed and successfully treated before considering the surgery. Undercorrection and overcorrection Some LASIK patients’ eyes may respond unpredictably to laser energy or may heal in an unusual fashion, leading to a significant undercorrection or overcorrection of their nearsightedness, farsightedness or astigmatism. Though this is disappointing to both the patient and the surgeon, undercorrection and overcorrection can usually be resolved with a re-treatment (enhancement). Retreatment rates for undercorrection and overcorrection appear to be falling. A 2004 study indicated that 15% of conventional LASIK patients required enhancements. (2) More recent reports suggest fewer enhancements are needed if newer LASIK technology and techniques are used. Your risk for undercorrection and overcorrection increases if you have a strong prescription. Regression Long-term studies with follow-up periods of 10 years or more have shown LASIK results to be very stable for most patients. However, in some cases there will be a mild loss of vision correction over time. One study found that 14% of patients who had LASIK to correct mild to moderate amounts of myopia (less than -6.00 D) needed an enhancement at some time during the 10-year follow-up period. The retreatment rate for higher amounts of myopia (-6.00 D to -10.00 D) was 25%. (3) It’s important to keep in mind that your eyes change over time whether or not you have LASIK. Sometime after age 40, nearly all of us need to wear reading glasses due to a normal age-related loss of focusing ability called presbyopia. And many of us will develop cataracts and other eye conditions as we age that may change our vision correction needs. So at some point, it’s likely you will still need corrective eyewear for certain activities after LASIK. Typically, the younger you are when you have LASIK surgery, the longer it will be before you need to worry about these changes. Flap complications The first step of LASIK is creating a flap of corneal tissue. This is done with a bladed instrument called a microkeratome or with a laser. Flap complications can include:
Epithelial ingrowth This complication occurs when fast-growing cells on the surface layer of the cornea – called the epithelium – migrate under the flap margin and start growing under the flap after surgery. Depending on its severity, epithelial ingrowth can cause blurred vision, discomfort and other problems or it can cause no problems at all. Epithelial ingrowth occurs infrequently after initial LASIK procedures but is more common after retreatments. This is because the original flap must be lifted during an enhancement, which can give epithelial cells a greater chance of ending up under the flap. A recent study conducted at George Washington University (Washington DC) found that epithelial ingrowth occurs in 0.2% of primary LASIK procedures and in 6.0% of enhancement surgeries. (5) Older patients appear to be at higher risk for epithelial ingrowth. Another recent study found that epithelial ingrowth occurs in 10% to 40% of patients undergoing a LASIK enhancement procedures, depending on the surgical techniques used. The average age of those in the study who developed epithelial ingrowth after a retreatment was 53 years. The average age of those who did not was 44 years. (6) Treatment of epithelial ingrowth involves lifting the flap, removing the epithelial cells from under the flap, and treating the flap interface with a dilute alcohol solution to discourage regrowth of epithelial cells. After treatment, a risk of recurrence of epithelial ingrowth remains. Corneal abrasion This complication is usually caused by the mechanism of the microkeratome during flap creation. It’s estimated that corneal abrasions occur in 5% of LASIK procedures in which the surgeon uses a microkeratome to create the flap. (7) Depending on their severity, corneal abrasions may heal without treatment or a bandage contact lens may be required until new epithelial cells form over the abraded area. Corneal abrasions can slow healing after LASIK and increase the risk of infection or inflammation. Using a laser to create the corneal flap reduces the risk of corneal abrasions during LASIK surgery. Inflammation Inflammation is a normal response to cellular damage and is the first step in tissue repair. But if inflammation is uncontrolled or is caused by a contaminated wound, it can interfere with healing and cause corneal haze that can result in permanent vision loss. Symptoms of inflammation after LASIK are eye redness, pain and a burning sensation. The most common type of corneal inflammation after LASIK is called diffuse lamellar keratitis, or DLK. Treatment of inflammation after LASIK usually consists of aggressive use of steroid eye drops. In some cases, the surgeon may need to lift the flap and remove inflammatory cells under the flap to prevent tissue damage and scarring. Prompt treatment will usually resolve the problem with little or no loss of visual acuity. The incidence of clinically significant inflammation after LASIK has been reported to range between 0.2% and 5.3%. (8) Infection Infection is rare after LASIK, provided you follow your doctors instructions. Your surgeon will prescribe antibiotic eye drops for you to use for several days after your surgery to help prevent infections. The reported rate of corneal infections after LASIK surgery is 0.03%. (4) Corneal shape changes Corneal ectasia is a rare complication of LASIK that is characterized by thinning and bulging of the cornea, in a process that resembles an eye disease called keratoconus. Though no one knows for sure what causes ectasia after LASIK, removing too much tissue from the cornea appears to be a risk factor. The incidence of ectasia after LASIK has been estimated at approximately 3 cases per 1,000 surgeries, (9) and most experts agree the risk of ectasia can be reduced further by careful screening of patients. Individuals with unusual corneal topography (a mapping of the shape and thickness measurements across the entire cornea) or a family history of keratoconus should be disqualified from LASIK surgery, say many surgeons. The primary symptom of ectasia after LASIK is blurred or distorted vision that cannot be corrected with eyeglasses. High astigmatism may also develop. A challenge in detecting and estimating the risk of ectasia is that can sometimes take 2 to 5 years after LASIK surgery for the condition to appear. A new treatment option for ectasia that is showing promise is a process called corneal collagen cross-linking with riboflavin (C3-R), which can strengthen and stabilize the cornea. Communicate with your surgeon No surgery should be taken lightly, and you should be aware of all risks involved. The best way to do this is to ask plenty of questions during your LASIK consultation, and discuss any and all concerns you have with your surgeon or other eye doctor(s) involved in your decision. Each LASIK surgery candidate is unique. The doctors helping you make this important decision should be able to discuss the risks and rewards of LASIK in terms that are specific to you. Keep your expectations realistic Though LASIK can usually provide 20/20 eyesight for most patients, that doesn’t mean your vision will be perfect after the procedure. Some people who see 20/20 after LASIK will still notice glare or halos at night. And though some people report their vision is sharper after LASIK than it ever was with eyeglasses or contact lenses, others will have the opposite experience, and feel their vision lacks the definition it had prior to surgery – even if they can read the 20/20 line in the doctor’s office. The best way to think about LASIK or any vision correction surgery is that it is capable of reducing your dependence on eyeglasses, but perhaps may not eliminate your need for eyewear completely. It’s possible you still may need glasses for certain tasks, like driving at night. And nearly everyone needs reading glasses once they reach a certain age after LASIK. If you expect nothing short of “perfect vision,” LASIK may not be the answer you’re looking for. Be sure to discuss your visual expectations with your eye doctor prior to deciding to have LASIK or other vision correction surgery. Sources:
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