LASIK (Laser in Situ Keratomileusis)

What is LASIK?

LASIK is a type of eye surgery to reduce nearsightedness and sometimes astigmatism and farsightedness. LASIK is the abbreviation for laser in situ keratomileusis. In this procedure an eye doctor removes very thin layers of tissue from the cornea. The cornea is the clear outer layer on the front of the eye.

Nearsightedness is when you have trouble seeing distant objects clearly. In farsightedness, it is difficult to see nearby objects clearly. Astigmatism is blurry vision that occurs when the cornea is uneven.

LASIK corrects only focusing problems, that is, problems that can also be corrected by glasses or contact lenses.

How does it work?

If you have perfect vision, light passes through your cornea and lens and reaches a focus point on the back of your eye (the retina). Nearsightedness occurs when your eye is too long and the focus point is in front of the retina. Farsightedness is when the eye is too short or your cornea is too flat, causing the focus point to be behind the retina. In astigmatism, the cornea is uneven and your eye cannot focus light rays sharply at any distance.

During LASIK, the surgeon uses a laser or surgical tool to remove the top layer of the cornea (the epithelium) as a flap. The surgeon then uses the laser to remove thin layers of tissue from the deeper layer of the cornea (the stroma). The removal of tissue changes the shape of the cornea so that light rays can focus on or closer to the retina, which improves your vision. At the end of the procedure, the surgeon replaces the flap of epithelium.

When is it used?

LASIK may correct your vision and reduce your need for glasses or contact lenses. It can be used to improve mild to moderately severe nearsightedness, mild farsightedness, and astigmatism. Be sure to talk to your doctor about your chances for improved vision.

Often both eyes are done at the same time. However, your doctor may prefer to do one at a time.

How do I prepare for the procedure?

Do not wear rigid contact lenses for 3 weeks before the surgery or soft contact lenses for 2 weeks before your appointment for evaluation for surgery. Contact lenses can change the shape of the cornea and prevent the accurate measurements that are needed for LASIK.

You will need to arrange for someone to take you home about an hour after the surgery. Allow for time to rest at home while your eyes heal.

Do not wear any makeup the day of surgery.

What happens during the procedure?

The surgery is done in a special office with laser equipment. The doctor numbs your eyes with eyedrops. Then he or she uses an instrument to cut part way into the cornea. The doctor leaves one edge of this tissue attached to your eye, forming a flap. The flap is then opened, like a door on a hinge. Your doctor uses the laser to remove thin layers of the inside of the cornea (the stroma) until it is the right shape to improve your vision. The doctor then closes the flap, which stays in place without stitches.

What happens after the procedure?

Usually you will be able to see well in a few hours. You will have little or no pain. Your eyes may feel dry for a few days or weeks. Your doctor can prescribe eyedrops to reduce the dryness.

What are the risks of LASIK?

As with any surgery, the results are not guaranteed. Some possible risks include:

• Your eyes may be over-corrected, and you may become farsighted.
• You may not get enough correction and still need glasses for distance vision.
• You may have scarring that causes glare or an irregular astigmatism.
• You may need reading glasses for close vision. After LASIK some people need to begin using reading glasses sooner than they would have without it. (Most people need reading glasses after about age 40 because of normal changes in their eyes.)
• Rarely, the cornea gets inflamed and may need treatment with eyedrops or more surgery.
• Very rarely, you may get an infection, which can cause your vision to be worse than it was before the procedure.

What are the benefits of LASIK?

Many people (90% or more) have at least 20/40 vision after LASIK. They do not need glasses or contacts for driving and many other activities.

Healing after LASIK surgery is usually faster than recovery after other types of refractive surgery because the flap (outer part of the cornea) is put back on the eye. This step also reduces the chance of infection.

LASIK can correct for greater degrees of nearsightedness than can some other types of refractive surgery.

If needed, your surgeon can repeat the procedure to fine-tune your vision.

When should I call my doctor?

Call right away if you have:

• unusual pain
• a sudden loss of vision
• a lot of drainage from your eye.