Seeing Stars: What is the difference between PRK and Epi-LASIK?

By Christopher J. Rapuano, MD

Published on September 22, 2007

Both PRK (photorefractive keratectomy) and Epi-LASIK are surface ablation refractive surgery procedures. PRK was the original excimer laser refractive surgery, developed in the early 1990s. Epi-LASIK is a new variant, which has gained popularity within the last 5 years. Both procedures involve removal of the surface layer of the cornea (the epithelium) which creates a corneal “abrasion.” The excimer laser treatment is then applied to the underlying cornea to reshape the eye to treat nearsightedness, farsightedness, and/or astigmatism.

PRK procedure

In the PRK procedure the epithelium is removed with a blade to expose the underlying cornea. Some surgeons place dilute alcohol on the corneal surface to loosen the epithelium, making it easier to remove. The resulting corneal “abrasion” is often somewhat large and irregular and takes 3-5 days to heal.

Epi-LASIK procedure

In the Epi-LASIK procedure the epithelium is removed with an Epi-Tome. This is a device which applies pressure on the eye with a suction ring and uses an oscillating blade to remove the epithelium. The original Epi-LASIK procedure separated the epithelial layer, moved it to the side, and replaced it after the laser treatment was performed in hopes of reducing pain and speeding visual recovery. However, most surgeons now feel that not replacing the epithelium provides better results.

Advantages and disadvantages

Advantages of PRK include no need for specialized equipment and no suction applied to the eye. Disadvantages include slightly longer healing time. Advantages of Epi-LASIK include slightly shorter healing time, with potentially less pain, faster recovery of vision, and less haze. Disadvantages include the need for specialized equipment, increased cost for the blade, raising the eye pressure with the suction ring, and the theoretical risk of making a cut that extends into the body of the cornea.

Both PRK and Epi-LASIK are excellent procedures, in terms of safety and efficacy. However, some patients may be better candidates for one rather than the other. You should discuss your specific examination results and your expectations with your surgeon before deciding which procedure is best for you.