January 22, 2010
Dear Mayo Clinic:
Is LASIK surgery considered safe? Is it always effective? I don't want to risk my vision since it's not terrible but would love to get rid of my contacts.
LASIK (short for laser-assisted in-situ keratomileusis) eye surgery is approved by the Food and Drug Administration (FDA). The procedure has been widely used for many years to correct vision problems, and the surgery is often successful. But it's not for everyone. The effectiveness and safety of the procedure depends on selecting the right candidates for LASIK, based on a person's medical history and a careful evaluation of the eyes before surgery. Proper evaluation requires a skilled ophthalmologist who has considerable experience performing LASIK.
LASIK is a form of refractive surgery. Refractive surgery changes the shape of the cornea — the transparent membrane that arcs over the pupil and the colored part of the eye (iris) — to bend (refract) light rays, so they focus more precisely on the retina rather than at some point beyond or short of the retina. This produces clearer, sharper vision, reducing or eliminating the need for eyeglasses or contact lenses. LASIK can be used to correct nearsightedness (myopia), farsightedness (hyperopia) and astigmatism.
To perform LASIK, a surgeon uses a special instrument called a microkeratome to cut a hinged flap of the top layer of the cornea and lift it away from the front of the eye. Then a laser is used to reshape the middle layer of the cornea called the stroma. Once that's completed, the cornea flap is repositioned. Within minutes, the flap adheres back to its natural position and heals without any additional treatment, allowing for rapid recovery. It's not uncommon for a patient's vision to achieve the intended correction within a few days following LASIK.
Although LASIK is a low-risk procedure, as with any medical procedure, some risks are involved. Possible complications include undercorrection, overcorrection and astigmatism, which may result in vision that isn't as clear as possible. Undercorrection can often be remedied with another refractive surgery to remove additional tissue. Overcorrection — when too much tissue is removed — is more difficult to fix. Astigmatism caused by uneven tissue removal during LASIK may require additional surgery to correct. Dry eyes and difficulty seeing at night are also possible complications from LASIK.
Some factors can increase the risk of complications associated with LASIK surgery. For example, if you have dry eyes, LASIK tends to make this condition worse. An autoimmune disease, such as rheumatoid arthritis, or an immunodeficiency disease, such as HIV, can increase the risk of incomplete healing and infection following LASIK.
Certain eye characteristics, such as thin corneas or extremely uneven corneal surfaces, may make the surgery more difficult to perform. People who have large pupils are prone to experiencing symptoms such as glare, halos, starbursts and double vision following LASIK. And, LASIK isn't recommended for people whose prescriptions are unstable. The general rule is that — to ensure the best results — a person's prescription for eyeglasses or contact lenses should remain unchanged for at least a year prior to refractive surgery.
LASIK is excellent for patients who depend on glasses throughout the day. However, LASIK doesn't effectively manage presbyopia — a common refractive error that develops as people age and causes difficulty reading small print or performing other close-up tasks. So even if you have LASIK, you may eventually still require reading glasses because of aging's effect on your eyes.
Overall, if you are keen on removing or eliminating your dependence on glasses and contacts, LASIK is a safe, reasonable procedure to consider. In particular, if you wear contact lenses all day, every day — 12 to 14 hours a day, for example — I would definitely encourage you to discuss the option of refractive surgery with an ophthalmologist. Contact lens wear isn't risk-free, and the possibility of complications from contact lenses increases with daily wearing time. The limited one-time risk of LASIK may actually be less than the day-to-day risk of extensive contact lens wear.
To find out if you're a good candidate for LASIK surgery, talk with an ophthalmologist who has training and experience in refractive surgery. The ophthalmologist can discuss the pros and cons with you in detail and help you decide if LASIK could be an appropriate choice.
—Dave Patel, M.D., Ophthamology, Mayo Clinic, Scottsdale, Ariz.