From 1980 until the middle of the 1990s, I performed thousands of RK procedures for the correction of myopia, as well as astigmatic keratotomy for the correction of astigmatism. In general, the results with these procedures were quite satisfactory as long as the patients' preoperative myopia and astigmatism were in the moderate range. There were, however, some serious limitations to incisional keratotomy, including:1. RK weakened the entire cornea in order to produce an effect, which could cause patients' vision to fluctuate. The accuracy and stability of the RK result depended primarily upon intraocular pressure.
2. It was not uncommon for RK to induce corneal irregular astigmatism, especially with a small optical zone or the use of large arcuate incisions intended to correct greater than 2.50 D of astigmatism.
3. It was difficult to consistently set the blade length for performing RK.
4. The Russian RK technique (in to out) produced many cases in which an incision trespassed into the optical zone.
Now, It's PRK
In my hands, PRK has completely replaced RK. The advantages of PRK include a stable result, easy reoperation, and the capacity to correct mixed astigmatism. The disadvantages of PRK include increased cost and a longer recovery period (4 days with a therapeutic bandage contact lens). Mitomycin C has virtually eliminated corneal haze as a postoperative complication of PRK, so that it can now be used following LASIK and RK.
In my practice, astigmatic cataract/IOL patients are informed prior to undergoing phacoemulsification surgery that a minimal fee ($200) will be charged for PRK. Patients are willing to pay this amount to improve their uncorrected visual acuity. The surgeon can also correct residual myopia or hyperopia simultaneously with the astigmatism.
In the end, most arguments for RK instead of PRK will likely revolve around cost and convenience to the surgeon. However, if the arguments between the two procedures are those related to quality of vision and safety, then I believe that PRK is clearly superior to RK.
PRK and LASIK correct refractive error by altering the shape of the front of the cornea, as does RK. However, PRK and LASIK preserve the stability of the posterior cornea, whereas RK weakens and changes the shape of the entire cornea. Therefore, factors such as the patient's age, sleep patterns, and intraocular pressure (especially early chronic open-angle glaucoma), as well as inconsistencies in blade length and variables in surgical technique will have a deleterious effect on the accuracy and stability of RK. These factors do not affect PRK or LASIK.
Twenty-first Century Refractive Surgery
RK was instrumental in changing the ophthalmic profession's perspective from that of “refractive surgery-phobic” to keratorefractive surgery's current, positive standing. However, RK is a technology from the latter part of the 20th century—surgeons should enter the 21st century with laser keratorefractive surgery in the forefront, and with our eyes wide open for further advances in refractive surgery (probably in the form of anterior chamber devices).