Photo-Refractive Keratectomy (PRK) is the oldest laser vision correction procedure. It became popular worldwide in the early 1990s and in the USA in 1995 when the excimer laser was first approved by the FDA for laser vision correction (LVC). The excimer laser brought tremendous advancements to the specialty known as “refractive surgery.” Prior to 1995 the predominate form of refractive surgery was Radial Keratotomy (RK), which involved making a series of incisions to change the shape of the cornea.
With PRK, surgeons utilized state-of-the-art computer technology combined with the accuracy and precision of the excimer laser to treat a much wider range of nearsightedness, farsightedness, and astigmatism than was possible with incisional reshaping of the cornea. PRK proved to be extremely successful, with the vast majority of patients having visual results of 20/20 to 20/40, which reduced or eliminated their dependence on glasses or contact lenses.
Refractive surgery continued to evolve over the years with improvements in excimer laser technology, diagnostic technology and surgical techniques. One of the major changes was the introduction (in the late 1990s) of Laser Assisted In-Situ Keratomileusis (LASIK). The primary difference between PRK and LASIK is that the surface of the cornea is treated in PRK while the inner tissue of the cornea is treated in LASIK. Both have similar success rates but LASIK offers patients less post-operative discomfort and a quicker return to functional vision. These patient benefits contributed to the explosion in popularity of laser vision correction with over a million procedures performed each year.
In spite of the popularity of LASIK, refractive surgeons have come to realize that not everyone is a good candidate for this procedure. LASIK requires a cornea of sufficient thickness to allow the surgeon to make a surgical flap and remove the proper amount of inner tissue. Therefore, patients with thin corneas could encounter complications and more visual side effects with LASIK. Some patients also have pre-existing problems such as dry eye, large pupils, and problems with the protective surface cells of the cornea (epithelium). Because of these factors and others, an increasing number of patients seeking LASIK are discovering that they may actually be better candidates for PRK.
The complication rates for LASIK and PRK are relatively the same. Both require the skill, knowledge and experience of an accomplished refractive surgeon. However, the potential complications of PRK are considered to be less severe than the potential complications of LASIK.
PRK is performed in the comfort and convenience of an outpatient, excimer laser suite. First, very powerful eye drops completely numb the eye. Next, the clear, protective surface layer (epithelium) of the cornea is loosened from the underlying layers of the cornea and is then either removed completely or moved to the side. Then, in a matter of seconds, the excimer laser is applied to the cornea, reshaping it to the correct focusing power. Unlike LASIK, the PRK patient experiences no heavy pressure sensation nor loss of vision during the procedure.
Some surgeons prefer to replace the epithelium after the laser treatment as sort of a natural protective bandage while the new epithelium takes hold. This variation to PRK is sometimes called LASEK or Advanced Surface Ablation. After the procedure, a protective contact lens bandage will be placed on the eye to make it more comfortable during the healing process. With PRK or any of its variations, it usually takes 3-5 days for the epithelium to fully heal.
You should expect some moderate discomfort for the first 24-48 hours after PRK. You will be given instructions on how to manage the discomfort as well as eye drops to speed healing and prevent infection. Most PRK patients notice an improvement in their vision immediately after surgery. However, the vision usually is somewhat blurred during the epithelial healing process. Your functional vision should return in 3 to 7 days while the full visual results may not be recognized for three weeks to several months. Because the return to functional vision is longer than with LASIK, many PRK patients prefer to have one eye treated at a time. If you prefer to have both eyes treated at the same session, you should make plans to accommodate your slightly blurred vision for the first week after surgery.
The decision to have laser vision correction is an important one that only you can make. It is important that you have realistic expectations and that your decision is based on facts, not hopes or misconceptions. The goal of any refractive procedure is to reduce your dependence on corrective lenses. Laser vision correction does not always create 20/20 or even 20/40 vision. Even if you have an excellent result, the quality of your vision may not be as good as it was with glasses or contact lenses. Your doctor will provide you with additional information about the procedure, possible side effects and complication, postoperative healing course and possible alternatives that will allow you to make a fully informed decision. Be sure to have all your questions answered before you have the procedure.
Finding our about the health of your eyes is your first step towards visual freedom. This is accomplished by calling your doctor to schedule a personal consultation. Should your refractive error fall within the corrective range of laser vision correction, more extensive tests will be necessary. This information will help you and your doctor determine if laser vision correction is in your best interest and, if so, which procedure will best suit your individual needs.