Health Letter, May 2013
Laser-assisted in situ keratomileusis, or LASIK surgery, is often promoted as an effective, low-risk way to regain 20/20 vision and avoid glasses or contacts. Unfortunately, these claims can be misleading. The truth is, while most people who receive LASIK surgery are happy with the results, the procedure is not always as effective as patients hope it will be. There also are a number of rare but serious risks from LASIK surgery that can lead to permanent loss of vision quality and, in extreme cases, irreversible blindness. These risks are higher for certain groups of patients, and people in such high-risk groups should not undergo the procedure.
If you are considering undergoing LASIK surgery, you should find a good doctor and work with her or him to obtain a careful assessment; make informed choices; and ensure proper care before, during and after surgery. Learn the facts about the procedure beforehand and understand the right questions to ask to make smart decisions and avoid putting your eyes at risk.
How LASIK surgery works
In LASIK surgery, a laser is used to permanently change the shape of the cornea, the clear covering of the front of the eye. A typical LASIK procedure involves using a mechanical blade or laser to cut a flap in the outer part of the cornea, leaving a small part attached at the edge of the flap to provide a hinge. That flap is then folded back, revealing the middle section of the cornea that focuses light onto the back of the eye. Pulses from a computer-controlled laser reshape the section, after which the front flap of the cornea is replaced.
LASIK surgery is the most common form of surgery used to modify the shape of the cornea, but other surgeries also are available that may be better for particular patients.
Effectiveness of LASIK surgery
LASIK and related surgeries can be used to improve vision in those who are nearsighted, farsighted or have astigmatism. Most LASIK surgeries are successful, and it is not uncommon for clinical trials to report that 95 percent of patients or more have 20/20 vision 12 months after surgery.
Most patients report being satisfied overall with their LASIK results, but many are disappointed to find that they still require glasses after surgery, at least some of the time. Additional surgery to further improve vision may not be possible, and patients may be forced to continue wearing glasses or contacts to correct vision even after surgery. In 2009, the Consumer Reports National Research Center surveyed almost 800 adults who had undergone laser vision-correcting surgery over the prior eight years. While most patients were satisfied with their results overall, nearly two-thirds said they still had to wear glasses or contact lenses at least occasionally.
A large number of patients will not see as well without glasses following LASIK surgery as they did with glasses before undergoing surgery. In one study of a recently approved LASIK device, out of 160 people with farsighted eyes receiving LASIK surgery, about half could see as well or better without glasses or contacts one year following surgery than they had seen when wearing glasses or contacts before the surgery. The remaining half had worse vision, and 1 in 10 had vision that was much worse.
Risks of LASIK surgery
LASIK surgery usually causes minimal pain and the healing time is short, about a week in most cases (although people should avoid contact sports and swimming for a month or more). It is common to feel burning, itching and discomfort in the first few days after surgery, and some experience sensitivity to light, glare, starbursts or halos around lights, and bloodshot eyes. For most people, these symptoms diminish over time and should be gone entirely within six months of surgery.
However, for a small number of people who undergo LASIK surgery, impairment to vision can be long-term or serious. If these complications occur, they may require another procedure or medical treatment, which may not resolve the problem. As a result of treatment, some people lose lines of vision on a vision chart that cannot be corrected with glasses, contact lenses or additional surgery. For example, in the recent trial described earlier, 3 percent of eyes that were treated lost the ability to see two or more lines on an eye chart, even when corrected with glasses or contacts.
People who can see well on an eye chart may still develop other eye issues. They could experience glare, halos and/or double vision that can seriously affect nighttime vision or the ability to see in low-contrast environments (such as low light or fog). This can interfere with important tasks, such as driving at night. LASIK surgery also can prevent a person’s eye from producing enough tears to keep the eye moist and comfortable. This condition, called “severe dry eye syndrome,” can permanently reduce visual quality by causing intermittent blurring and other symptoms.
Other problems with LASIK surgery can lead to temporary loss of vision or even, in extreme cases, blindness. One such complication involves damaging or severing the outer flap of the cornea. The rate of these problems varies depending on the patient population, procedure and surgeon’s level of expertise but is estimated to affect between 0.3 to 5.7 percent of participants in clinical trials. The flap of the cornea also can become detached or damaged after the surgery, something that occurs roughly 2 percent of the time. Also, the eye can become infected during or after surgery (which is estimated to have taken place in 0.03 percent of cases). Risks can be reduced by relying on a skilled surgeon, using only sterile products approved by the Food and Drug Administration (FDA), and ensuring proper eye care after surgery, but they cannot be eliminated.
LASIK surgery is relatively new, so its long-term risks and benefits are still unknown. The first laser was approved for LASIK eye surgery in 1998, meaning that patients have only been receiving the procedure on a widespread scale for 15 years. Little is known about the effects the procedure might have beyond that time frame.
Who should avoid LASIK surgery?
People with either very poor vision or vision that is already very close to 20/20 may not be good candidates for LASIK surgery. The exact range of vision that is appropriate will vary according to the specific device being used to perform the operation and is described in the device’s “indications for use,” found on the product’s FDA-approved professional labeling. People whose vision falls outside of the specified range should avoid surgery with the device.
Even slight deviations from the indication can have significant consequences. For example, one LASIK device was recently approved to treat people with hyperopia (farsightedness) of less than 5 diopters (a unit of measure of optical power) as well as other features. After the device manufacturer tested the device on patients with slightly worse hyperopia, up to 6 diopters, it decided not to share the efficacy data for these additional subjects with the FDA. Instead, the manufacturer requested a narrower indication that excluded the people with the most severe hyperopia. Though the outcomes for the patients who fell outside the narrower indication remain secret, it is not unlikely that the risks of surgery outweighed the benefits for these patients.
It is the eye surgeon’s responsibility to become familiar with the approved indication for the device he or she uses. A surgeon should evaluate a patient’s eyes prior to surgery and ensure that his or her condition is appropriate for the device’s indication.
Other risk factors also can affect whether LASIK surgery is appropriate. Patients should not receive LASIK surgery if they have recently required changes in their glasses or contact prescription or in cases of:
- eye disease, including glaucoma and herpes or other infection in the eye;
- eye injury or previous eye surgery;
- dry eyes, large pupils or thin corneas;
- diseases that affect the immune system, such as AIDS, lupus or rheumatoid arthritis; or
- certain eye conditions, such as keratoconus or thin corneas.
People who take steroids or medications that affect the immune system also may be poor candidates for LASIK surgery, because these medications may affect healing after the surgery. Patients taking medications that can cause changes in vision should not undergo LASIK surgery.
Finally, pregnant or nursing women should wait to undergo LASIK surgery until their infants have been weaned. Hormones produced during pregnancy and lactation can affect eyesight, and LASIK devices are generally not tested on women who are pregnant or nursing.
Patients should be cautious about selecting a doctor for LASIK surgery. It is important to shop around and select a doctor who is experienced with LASIK surgery and has a low rate of complications. It is a good idea to avoid surgeons promising “20/20 vision or your money back” or who advertise promises of no-risk surgery.
The FDA has received numerous complaints about eye care professionals and surgery centers that fail to inform consumers of the indications, limitations and risks associated with the LASIK procedure. In 2009, 2011 and 2012, the FDA issued warning letters to eye care professionals urging them to eliminate deceptive or misleading advertising, but some providers continue to publish misleading advertising that fails to explain the risks of LASIK surgery.
Advice for patients
If you have decided to pursue LASIK surgery, you should first obtain a baseline evaluation by an ophthalmologist to determine if you are a good candidate. Ask the opthalmologist whether you fit the indication for the surgical device they will use, and discuss any medications you are on or conditions you have. Also discuss the type of vision improvement you can expect to experience after surgery, as well as what types of risks may be involved.
It may be a good idea to consult at least two opthalmologists before deciding whether to have the procedure. These visits can be time-consuming and may cost money, but remember that results of your surgery will be permanent and not all surgeons will provide you with an adequate and honest assessment.
Expertise is extremely important in surgery. When you visit an opthalmologist, ask questions to determine his or her level of experience, including whether he or she is using a new technique and is experienced working with people who have your condition. Also ask if the surgeon is board certified. Learn how the surgeon keeps track of short- and long-term results for patients, and find out what percentage of prior patients had successful outcomes or experienced risks such as vision loss.
Also, confirm with the opthalmologist that the products he or she will use are FDA-approved. There have been several recent outbreaks of infection caused by drugs used in eye procedures that were made at compounding pharmacies or manufacturers selling “sterile” eye products that were not FDA-approved and not actually sterile.
Your surgeon should be willing to discuss severe or permanent side effects, even if the risk of experiencing these effects is very low. He or she also should provide you with a patient information booklet from the LASIK device manufacturer that can explain the procedure, describe risks and benefits, and instruct you on how to prepare for surgery and care for your eyes afterwards to prevent complications. Read this booklet carefully, and also read through the consent form your doctor will give you before surgery. Do not be afraid to ask questions about anything you do not understand.
The FDA has a useful website providing more detail on the benefits and risks of LASIK surgery, as well as what to expect before and after the procedure. Visit www.fda.gov and type the word “LASIK” into the search box on the upper right-hand corner of the website.