PRK: The Original Laser Eye Surgery

It may be hard to believe these days, when everything is "LASIK this" and "LASIK that," but PRK (photorefractive keratectomy) used to be the most common refractive surgery procedure.

Both are grouped under the umbrella "laser eye surgery," but each is a little different when it comes to advantages and disadvantages.

LASIK patients have less discomfort and obtain good vision more quickly (with PRK improvement is gradual and over a few days or even months), but many surgeons prefer PRK for patients with larger pupils or thin corneas.

PRK was invented in the early 1980s. The first FDA approval of a laser for PRK was in 1995, but the procedure was practiced in other countries for years. In fact, many Americans had the surgery done in Canada before it was available in the United States.

PRK is performed with an excimer laser, which uses a cool ultraviolet light beam to precisely remove ("ablate") very tiny bits of tissue from the surface of the cornea in order to reshape it. When you reshape the cornea in the right way, it works better to focus light into the eye and onto the retina, providing clearer vision than before.

Both nearsighted and farsighted people can benefit from PRK. With nearsighted people, the goal is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. Also, excimer lasers can correct astigmatism, by smoothing an irregular cornea into a more normal shape.

How surgery improves vision. See animation.

Before Surgery

If you are considering PRK, your first step is to choose a surgeon. [Read our article on how to choose a surgeon for advice on this subject.]

Your doctor will examine your eyes to determine exactly what kind of vision correction you need and how much laser ablation is needed. A corneal topographer will be used; this is an instrument that photographs your eye and creates a kind of "map" of your cornea. No one has a perfectly rounded cornea, and the topographer will display the corneal irregularities and the actual steepness or flatness that the surgeon must address.

Also your eye doctor will ask about other medical conditions you have. Some conditions may disqualify you altogether as a PRK candidate; others may mean a postponement of the procedure or special care afterward. [For more information on disqualifiers for LASIK and PRK, please read LASIK Criteria for Success.]

During Surgery

PRK is an ambulatory procedure; you walk into the surgery center, have PRK, and walk out again. In fact, the actual surgery usually takes less than a minute, and you're awake the whole time. Occasionally, the doctor will give a mild oral sedative beforehand.

Most people don't feel pain during PRK. Your eyes are first anesthetized with special drops. The doctor will have you lie down, then make sure your eye is positioned directly under the laser. (One eye is operated on at a time.) A kind of retainer is placed over your eye to keep your eyelids open — normally, this is not uncomfortable. It has a suction ring that keeps your eye pressurized and immobile.

The doctor uses a computer to adjust the laser for your particular prescription. You will be asked to look at a target light for a short time while he or she watches your eye through a microscope to make sure it remains in the correct position while the laser sends pulses of light to your cornea that painlessly remove the tissue. It's important to keep your gaze fixated on that target light in order to get the best results.

The laser machine will make a steady clicking sound while the laser pulses are happening, and you may smell a faintly acrid odor during the tissue removal. Don't worry, that's normal.

The higher your prescription, the more time the surgery will take.

The doctor may prescribe medication for any postoperative pain, but many people feel no more than mild discomfort or "scratchiness" afterward.

The surgeon has full control of the laser and can turn it off at any time. After the procedure is finished, you will rest for a little while. If you're having both eyes done the same day, the surgeon will probably do the other eye after a short period of time. Many people choose to have their second eye done a week later.

Basics of vision correction surgery How to choose a LASIK surgeon How LASIK works Cost of LASIK What is LASEK? Presbyopia surgery

After PRK

As with any kind of eye surgery, it's important that you follow your doctor's instructions to the letter. Get proper rest, fill and use any necessary prescriptions, and call your doctor immediately if you suspect a problem. What occurs after the surgery can affect your vision just as much as the surgery itself.

Immediately after PRK, the doctor will have you rest for a bit, then you can go home (someone else must drive). At home, you should relax for at least a few hours.

You may be able to go to work the next day, but many doctors advise a couple of days of rest instead. They also recommend no strenuous exercise for up to a week, since this can traumatize the eye and affect healing.

Avoid rubbing your eye (your doctor will tell you how long). In fact, you will be examined just about every day to make sure the epithelium is healing properly. You will probably wear a special "bandage" contact lens, use antibiotic drops for a few days, and apply anti-inflammatory drops for several weeks.

Most people achieve 20/20 or better vision with PRK (also true of LASIK). Some may achieve only 20/40 or not quite as good. In fact, 20/40 is fairly good vision. In most states, it is good enough for driving. Some patients may still need glasses or contact lenses following laser vision correction, though their prescription level will be much lower than before. [Read about outcome statistics elsewhere in this section.]

Postoperative complications can include infection and/or night glare (starbursts or halos that are most noticeable when you're viewing lights at night, such as while you're driving).

Even if you see perfectly after laser eye surgery, you may still need reading glasses or bifocal contact lenses once you hit your 40s. This is because the eye's lens stiffens as you age, a condition called presbyopia. Your distance vision will probably remain crisp, but seeing up close will be more difficult. However, researchers are studying ways to correct presbyopia surgically. So it's possible that you could have one of those procedures later, once they are FDA-approved. [Read more about surgical correction of presbyopia.]

All of these are important topics to discuss with your surgeon before deciding on the surgery