Home > Laser Vision Correction

Topics on this page include:

Introduction | Excimer laser | Procedure | Candidate requirements | Who can't have PRK | Common side effects

Introduction

Laser vision correction has replaced radial keratotomy as the preferred technique to correct vision problems because it can better predict the amount of refractive change that will occur as a result of the surgery. PRK can reduce or eliminate moderate nearsightedness or astigmatism. It is not a solution for cataracts or glaucoma.

The excimer laser is used to alter the shape of the cornea by removing a thin layer of tissue from the center of the cornea. PRK takes about five minutes to perform. The patient will need to wear a bandage contact lens for a few days until the corneal surface heals. Five to fifteen percent of patients still need corrective lenses after surgery.

Excimer laser

The excimer laser is used in PRK 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.

Procedure

Before the surgery, a corneal topography is taken of the eyes to measure the amount of correction needed. This procedure takes about ten minutes. No flap is created during PRK; the laser treatment is done on the surface of the cornea. The epithelial layer is removed with a scrubber or blade, which leaves a raw surface on the cornea. This may cause pain for a few days.

The laser produces a concentrated beam of high-energy ultraviolet light that is focused precisely on the cornea. The excimer laser delivers a series of cool, ultraviolet light pulses to vaporize the corneal tissue precisely. It removes 0.00025 millimeter per pulse. During the procedure, the laser's light energy is converted into chemical energy, which evaporates molecules of corneal tissue precisely. The epithelium regenerates over the cornea and the eye heals in three to five days. The patient's vision may take a few months to return to normal.

Candidate requirements

Candidates for PRK must be eighteen years old, have stable vision, and have no abnormalities of the cornea or external eye.

Who can't have PRK

There are a number of people who shouldn't have PRK. They include:

• Pregnant women.
• People whose vision has changed in the last twelve months.
• People who wear pacemakers.
• People who have difficulty healing.
• People with exceptional cases of myopia or hyperopia.

Common side effects

Common side effects for PRK include pain, light sensitivity, overcorrection, glare, and induced astigmatism.