Photorefractive Keratectomy (PRK), like LASIK, is a form of laser refractive surgery.
This means that a laser is used to reshape the cornea, correcting refractive errors such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. PRK was the first laser refractive procedure performed in the United States and the first to gain final FDA approval. While LASIK is more commonly performed than PRK today, PRK still represents a great option for patients who may not be ideal LASIK candidates due to thin or irregularly shaped corneas.
Let’s examine the steps in PRK and how they differ from LASIK. In LASIK, the first step is the creation of a thin flap of corneal tissue, either with a microkeratome blade in traditional LASIK or with a femtosecond laser in the modern blade-free LASIK procedure. That flap is then carefully folded back so that the excimer laser can reshape the central layer of the cornea, known as the stroma, correcting the patient’s refractive error. The flap is then folded back into place. PRK is similar to LASIK in that an excimer laser is used to reshape the stroma. The primary difference between LASIK and PRK is that in PRK, there is no flap created.
FLAP IS MADE
Numbing drops are administered so that the surgeon can operate on the eye without the patient feeling any pain.
The surgeon removes the outermost layer of cells, the epithelium, using a diluted alcohol solution.
Once the epithelial cells are removed, the excimer laser treatment is performed in the same way as LASIK. For LASIK as well as PRK, Hoopes Vision uses the Wavelight EX500 excimer laser, the newest, fastest and most precise vision correction laser in the United States. We have owned and used seven different treatment lasers since 1995. The EX500 is nearly ten times faster than the most commonly used excimer laser in the U.S.
This means you’ll receive laser vision correction with the highest caliber of safety and accuracy. Your eye’s individual reshaping is pre-determined and carefully calculated by measurements taken at your pre-operative appointment. Laser treatment of the cornea takes only a few seconds.
After the excimer laser treatment, the surgeon places a clear, soft contact lens, called a bandage contact lens, on the eye. These special bandage contact lenses do not contain any prescription correction, but simply protect the eye and keep the patient comfortable while the epithelial cells grow back.
The epithelium regenerates in approximately 72 to 96 hours; the bandage contact lens is typically removed by the doctor at a postoperative visit approximately five days after PRK.
LASIK and PRK both have similarly excellent long-term results. For the patient, the primary differences between PRK and LASIK have to do with recovery time and comfort. The great majority of LASIK patients report little or no discomfort and are able to return to most normal activities, including driving, as quickly as the day after surgery.
Recovery from PRK surgery is a little longer. For the first few days, while the corneal epithelium regenerates, PRK patients usually report hazy vision, some soreness, and light sensitivity. This typically clears up after the first few days, and most PRK patients are able to drive and return to work four or five days after surgery. Vision continues to improve over the course of the first few weeks after surgery, and by approximately the fourth week, vision is similar between PRK and LASIK patients. One technique doesn’t give better vision than the other.
BEFORE YOU GET LASIK
Frequent Asked Questions
Ideal candidates for PRK eye surgery are healthy and have realistic expectations of the results. Additionally, candidates must have a refractive error that is stable (has not changed for at least a year) and between +5.00 to -12.00 diopters. Patients with pre-existing conditions including collagen vascular disease, diabetes, rheumatoid arthritis, keratoconus, or glaucoma may not be good candidates for PRK. Patients should notify our surgeons of previous steroid use as this may also make them ineligible for PRK.
PRK, the earliest form of laser refractive surgery, is similar to LASIK. The main difference between these treatments is that PRK eye surgery does not involve the use of a laser to create a flap in the top layer of corneal tissue. Instead, a section of the outer, top layer of the cornea – the epithelium – is gently removed during the procedure.
Numbing drops are administered so that the surgeon can operate on the eye without the patient feeling any pain. While LASIK surgery requires the surgeon to create a corneal flap and fold it back to access the inner cornea, PRK requires the surgeon to remove a section of the surface layer (one to two cells thick) of the cornea called the epithelium.
After the section of epithelium has been removed, the surgeon reshapes the cornea with an excimer laser to correct the anomaly that has been causing vision problems. Once the cornea has been reshaped, the area is “bandaged” with a special contact lens that helps the eye feel more comfortable and allows the epithelium to heal.
It is important to take it easy and get plenty of rest during the first few days after the procedure. You may return to work and/or drive when you are confident with your vision and your comfort allows.
After surgery, the eye can feel as if it has experienced a scrape or abrasion. To minimize discomfort, a soft “bandage” contact lens is placed on the eye for four to five days to smooth and cover the surface until the epithelium has healed underneath. Vision is usually a little blurry at first but improves after the epithelium or surface has healed. Studies have shown that after three weeks, visual acuity of PRK patients generally matches that of LASIK patients.
PRK is primarily recommended for patients who have thin corneas, have irregularities show up on their topography scans (e.g. irregular astigmatism), or are in professions that are not allowed to have LASIK.
“My vision was very poor, and coupled with my astigmatism I did not think I would even be a candidate. The knowledgeable and friendly staff at Hoopes Vision put me through the most thorough exam I have ever experienced and determined that I would benefit best with the PRK procedure.”