Photorefractive Keratectomy (PRK)
Photorefractive keratectomy, or PRK, is a laser vision correction procedure that reshapes the cornea to correct mild to moderate conditions of:
- Nearsightedness, or myopia
- Farsightedness, or hyperopia
During the PRK procedure an excimer laser is used to remove a small amount of the front or anterior portion of the cornea to correct refractive errors . Unlike the LASIK procedure, where a flap is created to access the cornea, PRK removes the outer or epithelial layer of the cornea with the laser so that tissue can be removed from the surface. The process flattens the cornea and achieves the corneal steepening that is needed for vision correction.
Advantages of the PRK Procedure
PRK provides the surgeon with greater control over the location and amount of tissue being removed, which allows patients to achieve accurate results. PRK gently sculpts the cornea rather than cuts, allowing the surgeon to treat greater degrees of nearsightedness, as well as farsightedness and astigmatism.
Up to 95 percent of patients with a correction of up to -6.00 diopters achieved a vision of 20/40 or better after PRK, with up to 70 percent achieving 20/20.
Some of the advantages of the PRK procedure include:
- Less depth of laser treatment
- Patients with thin corneas are eligible for PRK
- No corneal flap complications
Candidates for the PRK Procedure
Before LASIK was available, PRK was the most commonly performed refractive surgery procedure. LASIK has several advantages over PRK, including:less discomfort, faster results and quicker recovery. PRK is still preferred for patients with larger pupils or thinner corneas who are not candidates for LASIK, because PRK maintains corneal strength while providing impressive vision correction.
The PRK Procedure
Before the PRK procedure begins, the eyes are numbed with anesthetic eye drops. The surgeon uses targeted laser energy to then shape the cornea. The surgeon will have complete control over the laser, throughout the procedure, for a highly precise and customized result designed to give each patient the best vision possible. The entire procedure takes only a few minutes to perform.
After the procedure, the eyes will be bandaged with a soft contact lens to protect the cornea. New cells, to replace the cells that were removed, will grow back over the next few days. The contact lens will be removed by the surgeon in a follow up examination.
Recovery After the PRK Procedure
After the PRK procedure is completed, patients will need to rest before returning to their home Patients may need to wear glasses after the procedure until their vision has stabilized. The surgeon will prescribe topical antibiotics to prevent infection and to keep the eyes moisturized.
While vision may seem to have improved initially, full results may take several days or weeks for full improvement to be seen. Patients may be able to return to work the next day, unless otherwise advised. Strenuous exercise should be avoided for at least a week, as this can affect the healing process. Patients will likely be able to see well enough to drive a car after two or three weeks.
Results After the PRK Procedure
The results of PRK are considered comparable to those of LASIK, although some patients may experience vision of only 20/40, and others may still need glasses or contact lenses after their procedure. PRK does not correct presbyopia, a natural change in the eyes that affects people over the age of 40, patients who need reading glasses will continue to need them after surgery. It is important for patients to maintain realistic expectations in order to be satisfied with the results of PRK.
Risks of PRK
As with any type of surgery, there are certain risks associated with the PRK procedure, including:
- Reaction to anesthesia
- Undercorrection or overcorrection
- Sensitivity to light
- Hazy vision
- National Institutes of Health
- Centers for Disease Control and Prevention
- Eunice Kennedy Shriver National Institute of Child Health and Human Development
- U.S. Department of Health & Human Services
- U.S. National Library of Medicine