Rochester, Minnesota - It is not typical for a person’s vision to regress after LASIK. Although the procedure may lead to some side effects and complications, they are uncommon. A thorough evaluation before surgery often can help avoid many of the potential problems that can happen after LASIK.

LASIK stands for laser-assisted in-situ keratomileusis. It is a type of refractive surgery - surgery that changes the shape of the transparent tissue, called the cornea, at the front of your eye. The surgery corrects vision problems such as nearsightedness, farsightedness and astigmatism, reducing or eliminating the need for eyeglasses or contact lenses.

LASIK is performed using a laser that removes tissue from your cornea to reshape it. To gain access to the cornea, a surgeon cuts a hinged flap about the size of a contact lens away from the front of the eye. After reshaping the cornea, the surgeon lays the flap back into place.

Vision is often very good right after surgery, but it can take up to several weeks for it to stabilize. In some cases, the first surgery may result in under-correction. This is more common in people who have higher prescriptions. If under-correction happens, another surgery may be needed to achieve the proper correction.

Long-term results from LASIK tend to be best in people who are carefully evaluated before surgery to ensure that they are good candidates for the procedure. Medical history, family history and other existing medical conditions can have an impact on the success of LASIK. The shape and thickness of your cornea also need to be thoroughly assessed to make sure you can undergo the procedure safely.

Potential side effects from LASIK include seeing glare and halos around lights, particularly at night. This generally lasts a few days to a few weeks. Some people experience more dryness in their eyes after surgery. Rarely, dry eyes may become a chronic problem following LASIK. People who have dry eyes before LASIK are at higher risk for chronic dry eyes after surgery than those who have not had that condition.

More serious complications of LASIK include eye infections that lead to scarring of the cornea, an irregular surface of the cornea from the laser, and problems with the LASIK flap during or after surgery. All of these are uncommon.

The most serious and the rarest complication is an eye disorder called post-LASIK ectasia. This condition changes the shape of your cornea years after surgery. In people who have ectasia, it may seem as if their vision has regressed. But it is much more serious than that. In some cases, ectasia may require a cornea transplant. The main risk factor for post-LASIK ectasia is an eye disease called keratoconus. If you have this disorder, or if you have a family history of it, you should not get LASIK.

Another eye problem that can mimic vision regression after LASIK is a cataract - clouding of the eye lens. As a cataract develops, some people who have had refractive surgery become nearsighted again. This problem requires cataract surgery and not further LASIK.

Because several serious eye issues can masquerade as vision regression, it is important to have your eye care professional investigate any change in vision after LASIK to find the underlying cause.

Overall, complications from LASIK are uncommon, especially when people are screened and evaluated carefully to confirm that they are good candidates for the procedure. The vast majority of people have positive results and are satisfied with the outcome of the surgery. As you consider if LASIK is right for you, talk to your eye care professional about the pros and cons of the surgery based on your individual situation. - Sanjay V. Patel, M.D., Ophthalmology, Mayo Clinic, Rochester, Minnesota.