If you are not be a good candidate for LASIK you may be a candidate for a procedure known as photorefractive keratectomy, or PRK. PRK offers the same visual outcomes as LASIK and has dramatically improved the vision of millions of people who were unable to have LASIK.
PRK is also known as LASEK (pronounced LAS-ECK), epi-LASIK, and surface ablation.
What is PRK?
Like LASIK, PRK is refractive surgery which uses the same excimer laser to reshape the cornea. Instead of creating a flap and then reshaping the deeper corneal layers, PRK works directly on the surface layers of the cornea. Consider it as LASIK without the flap.
For mild to moderate myopia, only 5% to 10% of the corneal thickness is removed. For extreme myopia, about 30% is removed. If you were to measure this tissue, its thickness would be that of one to three human hairs. The major advantage of PRK is that it retains the structure of the corneal dome.
History of PRK
First introduced in 1987, PRK was approved by the U.S. FDA in 1995. No microkeratome is used to create a corneal flap. Instead, the eye surgeon uses the laser to reshape the cornea one microscopic layer at a time. As public awareness of LASIK grew, PRK lost popularity because of the greater comfort and faster recovery of vision offered by LASIK.
Over the past decade, a newer generation of excimer lasers and more refined techniques have reduced the risks of PRK. Today PRK patients have an easier recovery. This has made PRK a viable option for many patients whose needs would not be met by LASIK.
Who Is a Candidate for PRK?
Most people who are candidates for LASIK are also candidates for PRK. The PRK procedure is an especially good fit for people with mild to moderate nearsightedness, farsightedness, and/or astigmatism. Individuals with thin corneas may be better candidates for PRK than for LASIK. As with any laser surgery, your corneas should be healthy and your vision should be stable for at least a year prior to the procedure. Also, except in certain situations, you need to be at least eighteen years of age to undergo this procedure.
Who Is Not a Candidate for PRK?
Anyone with an active outbreak of herpes simplex of the eye cannot have PRK. If you go six months without a recurrence of it, some doctors will do PR, giving you prophylactic medications before and after the procedure to lower the risk of a herpes simplex recurrence during recovery.
In general, pregnant women should avoid PRK and all vision correction procedures because pregnancy sometimes destabilizes one’s prescription during the third trimester. If your pregnancy is in an early stage and your vision hasn’t changed, you may be able to have PRK.
If you suffer from any major medical conditions, for example diabetes, or an autoimmune disease such as lupus or rheumatoid arthritis, it does not automatically disqualify you for PRK. You can talk with us about taking some specific steps to make PRK as safe as possible for you.
As with LASIK surgery, an experienced, board-certified ophthalmologist is preferable.
Preparing for PRK
To give your eyes time to return to their natural shape and thus allow for a more accurate vision correction, we will ask you not to wear contact lenses for up to a week before the date of your eye measurements. If you wear rigid, gas-permeable contact lenses, we may ask that you not wear them for up to three weeks before your measurements, for the same reason.
Whether to treat both eyes the same day, or to treat each eye on different days is a decision you and Dr. Davidorf can make together. Because the return of functional vision is delayed after PRK, some surgeons prefer to wait at least a week before treating the second eye. The main drawback of that is the inconvenience of going through two recovery periods, each 24 to 48 hours of pain or discomfort and with postoperative office visits.
Travel arrangements following PRK surgery are necessary, as you will be given a mild sedative prior to surgery.
Laser Epithelial Keratomileusis (LASEK) is similar to PRK because it doesn’t involve the creation of a corneal flap like LASIK, but instead of removing the epithelium, the thin layer of protective skin that covers the cornea, the epithelium is loosened with a diluted alcohol solution and moved aside. An excimer laser is then used to reshape the cornea during the procedure, and the epithelial flap is returned to its original position. Using this layer as a natural bandage, as opposed to removing it with PRK, may improve healing. The healing time for LASEK is longer than LASIK because the treatment is performed on the surface of the eye. A contact lens is placed in thhe eye to help begin the healing process. Even though LASEK has a long recovery time than LASIK, the post-operative results are essentially the same. Patients may choose to have LASEK rather than LASIK for a variety of reasons. The difference between LASEK and PRK is that the epithelial layer is removed during PRK. After the procedure new corneal cells will replace the ones removed during the surgery.