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 Topics on this page include: |
| What is LASIK? | Excimer laser | Procedure | Candidate requirements | Side effects | Advantages |
Laser assisted in situ keratomileusis (LASIK) uses a combination of surgery and a laser to treat nearsightedness and astigmatism as well as moderate levels of farsightedness. The surgeon surgically creates a flap of tissue on the front surface of the cornea. The flap is folded back and a laser is used to reshape the surface under the flap. For myopic or nearsighted eyes, the surgeon makes the surface flatter. For hyperopic or farsighted eyes, surgeons use the laser to remove peripheral tissue to make a steeper surface. For patients who suffer from astigmatism, tissue is removed from specific areas of the cornea to create a more spherical shape.
The excimer laser is used in LASIK surgery. It is a "cold" laser that doesn't burn tissue. It sculpts the surface of the cornea by removing small amounts of surface tissue one layer at a time. This process is known as ablation.
The operation normally takes five to fifteen minutes. The surgeon can do one or both eyes at one appointment. No injection needed, eyedrops are used to anesthetize the eye. There is a minimal amount of pain, but the patient will usually feel a pressure sensation during the procedure itself .
The surgeon uses a precise motorized instrument called a microkeratome to create a hinged flap of skin on the center of the cornea . After the flap is lifted, the excimer laser sculpts the surface under the flap . It reshapes only the top five to ten percent of the cornea. The amount of correction needed is programmed into the computer which controls the laser. It is accurate to a level of .25 microns. After the sculpting is complete, the flap is replaced.
It sticks to the surface of the cornea without requiring any stitches. The natural healing power of the cornea bonds the replaced portion without scarring. In the majority of cases, the patient can see better immediately. The surface of the eye heals in twenty-four to seventy-two hours, and the patient can then resume normal activities. The patient is usually able to return to work the day after surgery.
A plastic protective patch is worn over the eye for twenty-four hours and shields are worn at night for one week. There may be some discomfort for twelve to twenty-four hours. Generally, the only pain medication needed is oral medication normally used for pain or sleep.
Candidates for LASIK surgery must be eighteen years old. Their vision should be stable and they should have no abnormalities of the cornea or the external eye.
Some patients experience sensitivity to light or see halos around lights. These symptoms are usually short term. In some instances, undercorrection or overcorrection may require the patient to use glasses. The patient may also require a "touch-up" procedure several months later to achieve maximum results. The patient's vision may fluctuate during the healing process. Older people may still require reading glasses to correct presbyopia.
LASIK surgery has a number of advantages over wearing corrective lenses. There is a permanent improvement in the patient's vision. They can see clearly without glasses or contacts. LASIK doesn't deprive the cornea of oxygen like contacts can, and it doesn't cause allergies or red eyes.