EXCIMER LASER (PRK)

Now, we’ll do a similar analysis of Excimer Laser (PRK) correction of nearsightedness. This procedure has been approved in almost every country in the world and over 400,000 procedures have been performed worldwide. After extensive study, the FDA has now approved it in the U.S.

The procedure itself is quite different from radial keratotomy, though the final intent, to reduce nearsightedness, is the same. Unlike radial keratotomy, the Excimer laser procedure is performed by a highly sophisticated, computerized laser, rather than by hand.

In addition, the Excimer procedure is a "direct" method, whereas the RK procedure is an "indirect" method. The basic way both procedures correct nearsightedness is by flattening the cornea. RK does this indirectly by making incisions in the cornea, which cause weakening of the cornea and secondary flattening. This weakening is what causes the variable vision and the hyperopic shift, as well!

The Excimer laser, on the other hand, vaporizes superficial layers of the cornea to "directly" flatten it the amount needed to correct your level of nearsightedness. It’s more like peeling the top five sheets of paper off of a pad of paper. Since there are no deep cuts in the cornea, as in RK, there is no weakening of the cornea, and almost no variable vision.

Using the same criterion of 20/40 or better vision, as we did for RK, the success rates for the Excimer Laser Procedure in studies by Kim, Seiler, and Tengroth in three different countries were 91-92% in the low group, 92% in the middle group and 91% in the high group.

The U.S. FDA studies were even more impressive with over 95% of patients seeing 20/40 or better after a single Excimer laser procedure.

Complications consisted of slightly more pain than RK in the first 24 hours and mild starburst effect at night with headlights.

Studies on satisfaction rates for the two procedures have also been performed by Gimbel et al. They found that 98% of patients were happy with

Excimer results compared to 84% with RK. They also found that 90% of Excimer patients wore no corrective lenses compared to 60% with RK.

Based on the above results it would appear that the major differences in the two procedures are the higher success rates in the Excimer studies, especially in the middle and high groups, and the variable, progressive vision changes that occur with RK and do not seem to occur with the Excimer Laser.