LASIK Risks and Complications

By Marilyn Haddrill, with updates by Gary Heiting, OD;
reviewed by Brian S. Boxer Wachler, MD

If you are considering LASIK and are worried that something could go wrong, you might take comfort in knowing that sight-threatening complications from laser vision correction are rare. Also, many LASIK complications can be resolved with additional surgery or medical treatment.

Choosing the right eye surgeon probably is the single most important step you can take to decrease any risks associated with LASIK. An experienced, reputable surgeon will make sure you are properly screened and let you know up front if you aren't a good candidate for LASIK eye surgery.

Even if you are not qualified for LASIK, you still might be able to undergo vision correction surgery through other means such as PRK, LASEK, or implantable lenses. If you do decide to have LASIK, a responsible eye surgeon will work closely with you to resolve problems if they do develop. You can choose a LASIK surgeon by taking certain steps such as checking credentials.

How Common Are LASIK Complications?

Public confidence in LASIK has grown in recent years because of a solid success rate involving millions of successful procedures performed in the United States. With increasingly sophisticated technology being used for the procedure, most LASIK outcomes these days are very favorable.

The U.S. military also has adopted widespread use of refractive surgery including LASIK to decrease reliance of troops on corrective eyewear. This trend is particularly relevant because troops deployed for active duty are not allowed to wear contact lenses.

As of 2008, more than 224,000 military personnel had undergone laser vision correction. Since the procedure first was introduced in the military in 2000, researchers have conducted more than 45 studies regarding safety and effectiveness of LASIK and other procedures.

Outcomes have been overwhelmingly positive. Most soldiers see 20/20 or better after the procedure without corrective eyewear, and the rate of complications has been very low. According to one study, only one in 112,500 patients required medical disability retirement due to complications from laser vision correction during this eight-year period.

In a recent study of aviators from the U.S. Navy and U.S. Marine Corps who underwent wavefront-guided LASIK, all patients attained 20/20 uncorrected visual acuity (UCVA) within two weeks after surgery. When questioned about their satisfaction one month after surgery, 95 percent of the patients said the procedure was helpful to their effectiveness as an aviator, and 100 percent said they would recommend it to other aviators. Study results were presented at the 2008 annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS).

Retired U.S. Navy Capt. Steven C. Schallhorn, MD, a former fighter pilot and the first U.S. Department of Defense eye surgeon to perform refractive surgery, says he favors wavefront-guided LASIK because of outcomes producing superior night vision vital to the performance of fighter pilots.

LASIK Complication Rates Are Decreasing

The safety and effectiveness of LASIK continue to improve. Complications generally were more common in the early years of LASIK, when studies in the late 1990s indicated that up to 5 percent of people undergoing laser vision correction experienced some type of problem.

Experienced LASIK surgeons now report that serious complication rates can be held well below 1 percent, but only if surgical candidates are selected very carefully. For example, you may be eliminated as a LASIK candidate if you have certain pre-existing conditions, such as diabetes, that may affect how well your eye heals.

It's very important that you mention any health conditions you have and any medicines you take during your LASIK pre-operative exam and consultation. Your eye surgeon needs to know this information to properly assess your suitability for laser vision correction and your risk for complications. It is especially important to discuss any health condition you have that might hamper your ability to heal; this is one of the standard LASIK criteria used for assessment.

Also, you might want to take AllAboutVision.com's online LASIK screening quiz to help you anticipate what kinds of questions you may be asked to determine if you are a good candidate.

Make sure you mention any problem with dry eyes, which is one of the most common reasons you may be eliminated as a candidate. However, many people with mild to moderate dry eyes can be treated before LASIK or other laser vision correction is performed.

The Truth About LASIK Risks

 
Left: What someone with post-op starbursts might see at night. Right: Nighttime haloes.

While LASIK outcomes overwhelmingly are favorable, remember that — as with any surgery — risks of complications still exist. Fewer than 1 percent of patients still experience serious and ongoing vision problems following LASIK, because no surgical procedure is ever risk-free.

Even people who have excellent uncorrected visual acuity after LASIK based on eye chart testing still can have bothersome side effects. For example, it is rare but possible that you may see 20/20 or better after LASIK but still have symptoms such as double vision, unresolved dry eyes or difficulty seeing at night because of glare or halos around lights.

When you sign the LASIK consent form provided by your eye surgeon prior to surgery, you should do so with a full understanding that, even in the best of circumstances, a slight chance exists that something unintended could occur.

Thankfully, most cases of undesired outcomes after LASIK can be corrected with additional surgery (called an enhancement) or with medical treatment, such as in the case of dry eyes.

Common LASIK Complications

When LASIK complications occur, they may be associated with the creation of a hinged flap in the clear front covering of the eye (cornea), which is lifted for laser re-shaping of the eye. The flap then is replaced to form a type of natural bandage.

If the LASIK flap is not made correctly, it may fail to adhere correctly to the eye's surface. The flap also might be cut too thinly or thickly. After the flap is placed back on the eye's surface, it might begin to wrinkle. These microscopic wrinkles in the flap are called corneal striae.

These flap complications can lead to an irregularly shaped eye surface. Most such problems can be resolved through re-treatment of the eye with enhancement surgery.

Studies indicate that flap complications occur in from 0.3 percent to 5.7 percent of LASIK procedures, according to the April 2006 issue of American Journal of Ophthalmology. But inexperienced surgeons definitely contribute to the higher rates of flap complications. Again, remember that you can reduce your risk of LASIK complications by choosing a reputable, experienced eye surgeon.

Some problems associated with LASIK flap complications include:

Irregular astigmatism can result from a less than smooth corneal surface. Irregular astigmatism also can occur from laser correction that is not centered properly on the eye. Resulting symptoms may include double vision (diplopia) or "ghost images." In these cases, the eye may need re-treatment or an enhancement.

Diffuse Lamellar Keratitis (DLK), nicknamed "Sands of the Sahara," is inflammation under the LASIK flap that may have several causes. Some inflammation of the cornea after LASIK surgery is normal. But if it is uncontrolled, as in DLK, it can interfere with healing and cause vision loss. If DLK occurs, it usually responds to therapies such as antibiotics and topical steroids. The flap also might need to be lifted and rinsed for removal of inflammatory cells and to prevent tissue damage.

Keratectasia or keratoconus is bulging of the eye's surface that can result from a flap that is cut too deeply, when too much tissue is removed from the cornea during LASIK or when the cornea initially was weakened as evidenced from cornea topography mapping prior to LASIK. Resulting distorted vision likely cannot be corrected with laser enhancement, and gas permeable contact lenses or corneal implants (Intacs) may be prescribed to hold the cornea in place.

A promising new treatment for keratectasia (also called "ectasia") is corneal collagen cross-linking with riboflavin (C3-R). In this non-invasive procedure, eye drops containing riboflavin (vitamin B2) are placed on the cornea and then are activated with ultraviolet (UV) light. This strengthens the links between the collagen connective tissue fibers within the cornea to halt the bulging of the eye's surface.

In some cases, it may be possible to perform a laser enhancement of the eye after collagen cross-linking treatment to restore vision loss caused by post-LASIK ectasia or keratoconus.

Other, more commonly reported complications that can result from LASIK eye surgery include:

• Dry Eye After LASIK: Almost half of all patients reported problems with dry eyes after LASIK within the first six months, according to the April 2006 issue of American Journal of Ophthalmology. These complaints appear related to reduced sensitivity of the eye's surface immediately following the procedure. If you have this problem, temporary remedies such as artificial tears or prescription dry eye medication may be needed along with oral flaxseed oil capsules.
   
  After about six months to a year, however, most dry eye complaints disappear when healing of the eye is complete. People who already have severe dry eye usually are eliminated as LASIK candidates.
• Significant Undercorrection, Overcorrection, or Regression: This means that your outcome is less than optimal and makes it difficult to function in certain situations. There are various reasons for these problems. In many cases, the cause is simply that a patient's eyes did not respond to laser eye surgery in a predictable fashion. But it's also possible that results are related to an inaccurate diagnosis or incorrect settings programmed into software guiding the laser during eye surgery.
   
  Regression from "over-healing" occurs when your eyesight is optimal at first, but then begins to deteriorate over time. In most cases, a significant undercorrection or regression can be treated with additional laser vision correction or other refractive surgery methods such as conductive keratoplasty, once it is certain that the refractive error is stable.
• Eye Infection or Irritation: These problems are rare and may require treatment with eye drops containing antibiotics or anti-inflammatory medication such as steroids.
   
  When bacterial infection occurs after LASIK, it appears to be related increasingly to an antibiotic-resistant form of Staphylococcus aureus. Survey results indicating a growing problem with this type of infection were reported at the 2008 annual meeting of ASCRS.
   
  LASIK surgeons also reported that infections occurred more frequently with surface ablations such as PRK and when bladed instruments called microkeratomes are used to create the flap during LASIK surgery. ASCRS reports indicate that flaps that are lifted and replaced on the eye during LASIK, serving as a type of "natural" bandage, appear to create a more sterile surgical environment than PRK and other surface ablation procedures.

A Note About Presbyopia and Cataracts

If you are under age 40 when you undergo LASIK, remember that your reading vision naturally will change when you are older, due to presbyopia. Normal age-related changes in the flexibility of your eye's natural lens will cause you to slowly lose the ability to focus at closer distances. If you are nearsighted, you will lose your near vision when you wear your glasses but may be able to read comfortably by removing them.

Presbyopia is not caused by LASIK and will occur whether or not you have refractive surgery. You also might want to review options for eye surgery to correct presbyopia.

As you grow older, you also might develop cataracts. Again, this problem is unrelated to LASIK surgery. If you develop cataracts after LASIK, this is purely coincidental. Having LASIK will not limit your ability to have cataract surgery in the future, if that becomes necessary.

Other Resources:

*Satisfaction, success reported with laser vision correction in naval aviators. Ocular Surgery News. 4/9/2008.

[Page updated May 2009]