The cornea and lens combine to focus visual images on the back of the eye.

A normal image is focused on the Retina

When the overall length of the eye is too long, too short or if the cornea is not perfectly round, a refractive error occurs and the visual images are not in focus.

A blurred image forms when there is a refractive error

The cornea accounts for approximately two third of the focusing power of the eye. By surgically changing the corneal shape or curvature, most or all of the entire blur can be eliminated.
Laser In Situ Keratomileusis (LASIK) and Photo-Refractive Keratectomy (PRK) are two surgical techniques which utilize lasers to reshape or change the curvature of the cornea.

LASIK

LASIK had its origins about thirty years ago and was originally developed to treat patients who had poor vision due to corneal disease and scarring. It has now evolved into a successful technique for correcting refractive errors. The current procedure, done on an outpatient basis, involves both the use of conventional and custom laser surgery to correct nearsightedness, farsightedness and astigmatism. LASIK can correct a high degree of nearsightedness with or without astigmatism with excellent results (95% of patients achieve 20/40 vision or better).

In performing LASIK, anesthetic eye drops are used to numb the eye. The surgeon then uses a special instrument or laser to create a thin flap with a hinge in the cornea.

A flap is created with an instrument or a special laser

The flap is lifted back and the underlying cornea surface is prepared for laser treatment. The area of this surface and the depth of the remaining cornea tissue are precisely measured before the procedure to ensure proper treatment and patient's safety.

The flap is lifted back and a treatment surface is prepared

The eye is then positioned under the excimer laser which has been computer programmed to remove a precise and microscopic amounts of the internal cornea tissue. Removal of the tissue changes the curvature of the cornea. If the patient is nearsighted, tissue closer to the central part of the cornea is removed to decrease the curvature or flatten the cornea. If a patient is farsighted, tissue in the peripheral part of the cornea is removed to increase the curvature of the cornea.

Excimer laser is used to reshape the cornea

To correct for astigmatism, certain amount of cornea tissues at specific angles are removed to create a round and even cornea in all directions.

Astigmatism can also be corrected during the laser treatment

After the laser has been used, the flap is returned to its original position. The cornea tissue has extraordinary natural bonding qualities that allow effective healing without the use of stitches.

The flap is placed back and allowed to sealed down

Since only local anesthetic is used, patients remain awake during the procedure. The entire procedure takes only a few minutes. Improved vision is often possible on the day following the surgery. Eye drops and night protection are necessary for designated periods of time.

Advantages of LASIK include:

• Faster healing time
• Rapid visual recovery
• Less risk of scarring
• Less risk of corneal haze
• Less post-op discomfort
• Both eyes are usually performed at the same time
• Treatment of a wider range of nearsightedness

PRK

Photo-Refractive Keratectomy, PRK, is another method of surgically reshaping the cornea using the excimer laser. The difference between LASIK and PRK is that for PRK, the corneal flap is not created before the laser treatment.

The outer layer of the cornea remains in place and the
laser removes tissue directly from this outer layer.

PRK is used for low to moderate amounts of nearsightedness.

Just as in LASIK, the laser treatment requires less than a minute. But unlike LASIK, the healing period time is longer and there may be slightly more discomfort during the first few days after surgery. The correction for nearsightedness, farsightedness and astigmatism is the same as in LASIK. The corneal curvature is changed so that the visual images are properly focused on the back of the eye. PRK is often performed when patient's natural inner cornea layer is too thin to remove for LASIK surgery.

Refractive surgery decrease the glasses need for most patients, but if you are in your forties and older, you may still need reading glasses after surgery. The vast majority of patients are happy with their vision after refractive surgery. Like any surgical procedures, there are some risks, but these are low and should be discuss and thoroughly reviewed before any procedure.