LASIK Risks and Complications – Safety of Laser Eye Surgery
Like any surgery, LASIK and other vision correction procedures have some risks and possible complications. But serious complications from LASIK, PRK and other laser procedures are uncommon, and significant vision loss from these procedures is rare.
How Frequently Do LASIK Complications Occur?
Advances in LASIK technology and surgical techniques have improved outcomes and decreased risks and complications associated with the procedure. Experienced LASIK surgeons report that serious complications can be held well below one percent 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 during and after surgery.
As part of your LASIK consultation and pre-operative exam, your doctor will thoroughly evaluate the health of your eyes to rule out potential problems—including 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 did not 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 is difficult to determine the exact risk of LASIK complications. There is no centralized organization or agency that collects data about LASIK outcomes, 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 After LASIK
Nerves within the cornea 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 abate within a few weeks to a few months after LASIK, some people will have persistent dry eye problems following the procedure. Symptoms of dry eye include discomfort, a feeling something is "in" the eye (called a foreign body sensation) sensitivity to light and blurred vision.
In a recent study, 20 percent 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 LASIK dry eye usually involves frequent use of artificial tears. For more severe cases, medicated eye drops may be prescribed to help your body increase tear flow. Also, tiny silicone plugs may be inserted in the drainage ducts of your eyelids (a procedure called punctal occlusion) to keep more tears on your eyes and relieve dry eye symptoms. Nutritional supplements like flaxseed oil also may be helpful in relieving some dry eye conditions.
Due to the increased risk of dry eye problems after LASIK, people who have pre-existing dry eye are not good candidates for LASIK until the dry eye condition has been successfully treated.
Undercorrection and Overcorrection
Some peoples' eyes respond unpredictably to laser energy during LASIK surgery or heal in an unusual fashion after the procedure. These factors can cause a significant undercorrection or overcorrection of nearsightedness, farsightedness or astigmatism. Though undercorrections and overcorrections are disappointing to both patients and surgeons, they usually can be resolved with a LASIK re-treatment (also called a LASIK enhancement).
Retreatment rates for undercorrection and overcorrection appear to be falling in recent years. A 2004 study indicated that 15 percent of conventional LASIK patients required enhancements.2 More recent reports suggest fewer enhancements are needed when newer LASIK technology and techniques, such as wavefront LASIK, are used.
Your risk for undercorrection and overcorrection increases if you have a high degree of nearsightedness, farsightedness or astigmatism prior to LASIK.
Regression of Refractive Error
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, a mild loss of vision correction occurs over time. This return of some of the pre-operative refractive error is called regression.
One study found that 14 percent of people 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 percent.3
It is important to keep in mind that your eyes can change over time whether or not you have LASIK. Sometime after age 40, nearly everyone needs to wear bifocals or reading glasses due to a normal age-related loss of focusing ability called presbyopia. Also, many people develop cataracts and other eye conditions as they grow older. In addition to making vision less distinct, these conditions can cause nearsightedness, farsightedness and astigmatism to develop.
If you choose to have LASIK, at some point, perhaps years after surgery, it is likely you will need corrective eyewear for certain activities. Typically, the younger you are when you have LASIK surgery, the longer it will be before you experience this change.
Flap Complications
The first step of LASIK surgery is creating a flap of corneal tissue. In conventional LASIK, this is done with a bladed instrument called a microkeratome. In all-laser LASIK, the flap is created with a femtosecond laser.
Flap complications can include:
- Incomplete flaps. These partial flaps are usually caused by a malfunction of the microkeratome.
- Buttonhole flaps. This occurs when the flap is cut too thin, creating a hole in the center of the flap.
- Free caps. This is the term used to describe when the hinge of the flap is cut off and nothing remains to keep the flap attached to the eye.
Flap complications have been reported to occur in 0.3% to 5.7% of all LASIK procedures.4 The risk of most flap complications can be reduced if a laser, rather than a microkeratome, is used to create the flap.
Epithelial Ingrowth After LASIK
This complication occurs when fast-growing cells on the surface layer of the cornea—called the epithelial cells—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 it 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 to migrate under the flap. One recent study found that epithelial ingrowth occurs in 0.2 percent of primary LASIK procedures and in six percent of enhancements.5
Older patients appear to be at higher risk for epithelial ingrowth. Another recent study found that epithelial ingrowth occurs in 10 percent to 40 percent of 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 During LASIK Surgery
This complication is usually caused by the mechanism of the microkeratome during flap creation. It's estimated that corneal abrasions occur in five percent 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. In some cases, a bandage contact lens may be required until new epithelial cells grow over the abraded area.
Corneal abrasions can slow healing after LASIK and increase the risk of infection or inflammation. The risk of corneal abrasions is reduced in all-laser LASIK.
Inflammation After LASIK
Inflammation is a normal response to cellular damage and is the first step in our body's healing response to an injury. But if inflammation of the eye after LASIK is uncontrolled or is caused by a contaminated wound, it can interfere with healing, cause corneal haze, and result in permanent vision loss.
Symptoms of inflammation after LASIK are eye redness, pain and a burning sensation. The most common type of inflammation of the cornea after LASIK is diffuse lamellar keratitis, or DLK.
Treatment of DLK 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 percent and 5.3 percent.8
Infection After LASIK
Infection is rare after LASIK, provided you follow your doctor's 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 eye infections after LASIK surgery is 0.03 percent, or 3 out of every 10,000 surgeries.4
Corneal Ectasia After LASIK
Corneal post-LASIK ectasia is a rare complication characterized by thinning and bulging of the cornea. In many ways, corneal ectasia after LASIK resembles an eye disease called keratoconus.
The cause of ectasia after LASIK is unknown, but the removal of too much tissue from the cornea during the procedure appears to be a risk factor.
The incidence of ectasia after LASIK has been estimated to be 3 cases per 1,000 surgeries.9
Most experts believe careful screening of patients can reduce the risk of ectasia further. For example, individuals with unusual pre-operative corneal topography or a family history of keratoconus should be disqualified from LASIK surgery, say many surgeons. These patients should seek keratoconus treatment before undergoing any other vision correction procedure.
The primary symptom of ectasia after LASIK is blurred or distorted vision that cannot be corrected with eyeglasses. High astigmatism may also develop. Estimating the true risk of post-LASIK ectasia is especially challenging, because sometimes it can take two to five years after surgery before signs and symptoms appear.
A new treatment for ectasia that shows promise is corneal collagen cross-linking with riboflavin (C3-R), which can strengthen and stabilize the cornea. This procedure is also being used for the treatment of keratoconus.
Communicate with Your LASIK Surgeon
No surgery should be taken lightly, and anyone considering LASIK should be aware of all risks involved. The best way to do this is to ask your LASIK surgeon plenty of questions during your pre-operative consultation. Be sure to discuss all concerns you have with your surgeon or other eye doctor(s) involved in your decision.
Many factors are taken into account to determine if you are a good candidate for LASIK surgery. 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 most people who have LASIK enjoy 20/20 eyesight without corrective lenses after surgery, this does not mean your vision will be perfect after the procedure.
Some people who see 20/20 after LASIK notice glare or halos at night. And while some say their vision after LASIK is sharper than it ever was with eyeglasses or contact lenses, others will have the opposite experience, and feel their vision after LASIK lacks the definition it had prior to surgery—even if they can read the 20/20 line on the eye chart in their doctor's office.
The best way to think about LASIK or any vision correction surgery is to expect it to improve your vision, but also to be aware that it may not completely eliminate your need for eyeglasses. It is 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 right choice for you. Be sure to discuss your expectations with your eye doctor prior to deciding to have LASIK or other vision correction surgery.
LASIK Alternatives
If you and your LASIK surgeon decide you are not a good candidate for LASIK, there are other vision correction procedures that may be a better fit. Ask your doctor to discuss these options, which include PRK, LASEK, Epi-LASIK, and lens-based surgeries, including phakic IOLs such as the Visian and Verisyse implantable lenses, and refractive IOLs for a procedure called refractive lens exchange.
If you are over age 40 and have presbyopia, you may want to consider a presbyopia correction surgery such as conductive keratoplasty (CK) or refractive lens exchange with an accommodating IOL such as the Crystalens implant or a multifocal IOL like the ReSTOR or ReZoom lens. If you have cataracts, these lenses can also be used during cataract surgery to give you greater independence from reading glasses after surgery.
Each of the above procedures has risks and potential complications as well. Be sure you fully understand the rewards and risks of any vision correction procedure before you sign the consent to proceed with surgery.
Sources:
1. Dry eye after LASIK for myopia: Incidence and risk factors. European Journal of Ophthalmology. Jan 2007.
2. Tracking CustomCornea's early clinical outcomes. Optometric Management. Feb 2004.
3. PRK, LASIK stable at 10 years in large series. Ocular Surgery News. Jan 1, 2007.
4. LASIK risks justify consideration of surface ablation techniques. Ocular Surgery News. Apr 15, 2007.
5. Epithelial ingrowth is primary LASIK complication. Ophthalmology Times. April 1, 2007.
6. Epithelial ingrowth seen increasing in older population. Ophthalmology Times. Sep 1, 2007.
7. A new generation of LASIK. Optometric Management. Sep 2007.
8. Determining DLK after LASIK. Contact Lens Spectrum. Dec 2007.
9. Numerous risk factors found for corneal ectasia after LASIK. Ophthalmology Times. Aug 1, 2007.
Note: This information is for general education purposes only. It is not to be used as a substitute for medical advice from your eye doctor or refractive surgeon.
