PRK was the Forerunner to LASIK.
PRK was first FDA approved in 1995. It was performed earlier in many other countries. Other countries are not as strict on new technologies.
PRK Different from LASIK
It is performed without making a flap. The epithelium is the outer layer of the cornea just like the outer cells of the skin. The central portion of the epithelium is removed prior to the laser being used. This is done with a blade or rotary brush to remove the central 8 or 9 mm.
Laser Portion of the Surgery
The Excimer laser is then used to remove or ablate the tissue on the cornea in a precise manner to change the shape of the cornea. This change in shape of the cornea results in correcting a person’s glass prescription.
Healing After PRK
The disadvantage of PRK is that the epithelium has to regenerate and cover back over the cornea where the laser procedure was performed. This can cause a significant amount of pain for 4 or 5 days until the epithelium has healed. The cells gradually cover back over the defect and the surface becomes smooth again. This also results in a longer time period until the vision improves. It may take up to 2 weeks or longer to gain good vision. The vision will gradually continue to improve for a few months depending on the amount of surgery needed to correct the vision. Most doctors will insert an extended wear soft contact lens to help with the comfort and healing. The contact lens is usually left in place for 4 or 5 days until the epithelium has healed and the eye is feeling comfortable.
In the beginning time period of PRK surgery, corneal haze or clouding of the cornea could occur. This may result in blurred vision due to this clouding of the cornea. The more surgery required to correct the vision and the younger the patient, makes the clouding of the cornea more likely. Newer lasers have decreased the incidence of corneal haze. Also some doctors use a drug called Mitomycin C for people with large refractive errors and younger age patients. It is applied to the cornea after the laser is performed. This drug helps in reducing the chance of corneal haze. The vision results with PRK are excellent.