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LASIK Risks and Complications

By Brian S. Boxer Wachler, MD

LASIK and other types of laser eye surgery, such as PRK and LASEK, have an excellent safety profile and a very high success rate. They are designed to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism, and can allow you to lead a life without glasses or contacts.

Sight-threatening complications such as complete or partial loss of vision from LASIK surgery are extremely rare, and many side effects and laser eye surgery complications can be resolved with additional surgery or medical treatment.

Like any other surgery, however, there are potential risks, side effects and limitations you should be fully aware of before electing to undergo the procedure. Choosing a skilled and experienced LASIK eye surgeon can help mitigate these risks and enable you to achieve the best possible results from laser eye surgery.

One of the most important aspects of successful vision correction is that you're a suitable candidate. Your eye doctor will perform an advanced diagnostic eye exam to determine your suitability for LASIK surgery. He or she will evaluate: the shape and thickness of your cornea; pupil size; refractive errors; the moistness of your eyes (to check for dry eye syndrome; general health and medical history; and any medications you are taking.

Even if you are not a good candidate for LASIK, you might still be able to benefit from other vision correction surgery such as PRK, LASEK or implantable lenses.

LASIK Eye Surgery Risk Factors and Limitations

Not everyone is a suitable candidate for LASIK eye surgery. Certain conditions and anatomical factors can put you at an increased risk of an undesirable outcome or limit optimal LASIK results.

These include: thin or irregular corneas; large pupil size; your degree of refractive error; whether you suffer from dry eyes; your age; whether your vision is stable; whether you are pregnant; and if you have certain degenerative or autoimmune disorders.

For a full checklist on LASIK risk factors and whether or not you are an appropriate candidate, read our LASIK Criteria for Success.

LASIK Side Effects and Complications

LASIK eye surgery has been performed on millions of people in the United States over the past 15 years or so, and experienced LASIK surgeons report that serious complication rates can be held below 1 percent. Common LASIK complications and side effects are listed below and most can be resolved with medical treatment or additional "enhancement" surgery.

Temporary discomfort and vision disturbances. Discomfort during the first few days following LASIK surgery, such as mild irritation and light sensitivity, is normal and to be expected. During the first few weeks or months you also may experience: halos, glare and starbursts in low vision, especially at night; dry eye symptoms; hazy vision; and reduced sharpness of vision. In the vast majority of cases, these problems are temporary and disappear completely within three to six months.

Flap complications. The LASIK procedure involves the creation of a thin hinged flap on the front surface of the cornea. This is lifted during surgery for laser reshaping of the eye. The flap is then replaced to form a natural bandage.

If the LASIK flap is not made correctly, it may fail to adhere properly to the eye's surface or cause microscopic wrinkles in the flap called corneal striae (STRIE-ee). These flap complications can lead to an irregularly shaped eye surface and distorted vision.

Studies indicate that flap complications occur in from 0.3 to 5.7 percent of LASIK procedures, according to the April 2006 issue of American Journal of Ophthalmology. In a study of 3,009 consecutive LASIK surgeries performed August 2002 through July 2009 using a femtosecond laser for flap creation, flap complications occurred in fewer than one-half of 1 percent (0.37 percent) of these procedures, and all complications were successfully managed within the same surgical session.

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. This is caused by an unequally curved corneal surface. Irregular astigmatism also can occur from laser correction that is not centered properly on the eye or from irregular healing. Resulting symptoms may include double vision (diplopia) or "ghost images." In these cases, the eye may need re-treatment or enhancement surgery.
• Epithelial ingrowth. This is when cells from the outer layer of the cornea (epithelium) grow under the flap after LASIK surgery. In most cases, epithelial ingrowth is self-limiting and causes no problems. But in some cases (reported to be 1 to 2 percent of LASIK procedures), symptoms of discomfort and/or blurred vision can occur, and additional surgery is needed to lift the flap and remove the epithelial cells.
• Diffuse lamellar keratitis (DLK). Nicknamed "Sands of the Sahara," this 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. Also, the flap might need to be lifted and cleaned for removal of inflammatory cells and to prevent tissue damage.
• Keratectasia or keratoconus. This is a very uncommon bulging of the eye's surface that can result when too much tissue is removed from the cornea during LASIK or when the cornea prior to LASIK is weak as evidenced from corneal topography mapping. Rarely does keratoconus develop after LASIK with no known risk factors.
  
  Enhancement laser surgery is usually not suitable, and gas permeable contact lenses or corneal implants (Intacs) may be prescribed to hold the cornea in place, or a treatment called corneal collagen crosslinking may be performed to strengthen the cornea.

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

Dry eyes after LASIK. LASIK surgery can cause a decrease in tear production and cause your eyes to feel scratchy and blurry. Almost half of all patients experience some degree of temporary dry eye syndrome, according to the April 2006 issue of American Journal of Ophthalmology.

Dry eyes caused by LASIK typically is a temporary condition and can be alleviated using topical and oral treatments.

Most complaints of dry eyes disappear when healing of the eye is complete, which usually takes about six months. People who already have severe dry eye usually are eliminated as LASIK candidates.

Significant undercorrection, overcorrection or regression. Not everyone will achieve 20/20 vision after LASIK eye surgery, and contacts or eyeglasses for some or all activities may still be required in rare cases. If the laser removes too much or too little corneal tissue, or your eye's healing response was not typical, your best vision outcome will be less than optimal. In addition, if the laser removes tissue in an uneven manner or your eye heals unevenly, astigmatism can result.

In many cases, the cause of a less-than-perfect outcome is that your eyes did not respond to laser eye surgery in a predictable manner. Another possible cause is that your eyesight may be optimal at first but regress over time due to "over-healing."

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. While rare, LASIK surgeons report that infections occur more frequently with surface ablations such as PRK. At the 2008 annual meeting of the American Society of Cataract and Refractive Surgery (ASCRS), researchers reported that the LASIK flap, which is lifted during surgery and then replaced to serve as a type of natural "bandage," seemed to create a more sterile surgical environment than PRK and other surface ablation procedures.

Eye infections after LASIK surgery typically are temporary, and can be treated with antibiotic eye drops or anti-inflammatory medication such as steroids.

How Common Are LASIK Complications?

The safety and effectiveness of LASIK surgery continues to improve, thanks to increasingly sophisticated technology and optimal patient selection.

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. These days, this number is under 1 percent for serious complications.

A worldwide review of LASIK published in 2009 showed that more than 95 percent of people who had LASIK surgery between 1995 and 2003 were satisfied with their outcome.

Public confidence in LASIK has grown in recent years due to the solid success rate of LASIK surgery outcomes. The U.S. military also has adopted widespread use of laser eye surgery to decrease reliance of troops on corrective eyewear. 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.

LASIK outcomes have been overwhelmingly positive. Most military patients 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 another study, all the aviators from the U.S. Navy and U.S. Marine Corps who underwent custom or wavefront-guided LASIK attained 20/20 uncorrected visual acuity 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 ASCRS annual meeting.

A new study by the FDA, in conjunction with the National Eye Institute and U.S. Department of Defense, currently is underway. The "LASIK Quality of Life Collaboration" will determine the percentage of patients with significant quality of life problems after LASIK surgery and identify predictors of these problems.

A national multi-center clinical study also will be conducted to assess outcomes of the LASIK procedure in a general patient population. The project is expected to be completed in 2012.

Laser eye surgery has successfully treated millions of patients and has high patient satisfaction rates. However, as with any surgery, LASIK involves potential complications. It is important for you to weigh the benefits and risks before choosing to go ahead with surgery.

[Page updated May 17, 2013]