|RADIAL KERATOTOMY SURGERY(historic interest only)|
A Japanese doctor by the name of Sato,first performed this procedure in the 1950's. Many successful cases were performed, but because of poor techniques, most cases eventually ended with a total loss of vision and the procedure was abandoned. In the late 1970’s the procedure was revived in Russia, with improvements in technique, and later brought to the United States with even further refinements.
Because of the lack of knowledge about the safety and the results of this technique, a large multicenter study was established called the "Perk" study at many University's around the country. The surgery was performed by well trained surgeons all using the same equipment and techniques. The basic technique consisted of making 8 incisions in "spokewheel" fashion in the cornea, the front surface of the eye. The incisions were made by hand with very sharp diamond knives. The incisions were made very deep to 95% of the depth of the cornea.
The data was collected and reviewed at 1, 3, 5, and recently 10 years. The results have been published and are controversial. The basic findings for each of the intervals published were basically the same. Only the percentages of success, failure, and complications changed. The statistics are based on reduction in nearsightedness to useful levels, which is considered to be 20/40 vision. This is the legal level for driving without glasses in all 50 states.
At 10 years after RK, results for low nearsightedness between 2 and 3 units, showed 92% were 20/40 or better. For middle nearsightedness between 3 and 4.5 units, 86% were 20/40 or better. For high nearsightedness between 4.5 and 8 units, 77% were 20/40 or better.
Twenty percent of cases needed second or third surgeries, referred to as enhancements.
The results don’t sound too bad. But what about the problems and complications? I find, as a physician, that most people ask the wrong questions about surgeries! People always ask about the success rates, which are important, but I want to know what the failure rate is and what problems comprise the failure rate! If I told you that an eye surgery procedure has a 98% success rate you would think that's really great! But, what if the 2% failure rate was total loss of vision! This is not the case, of course, for any of these procedures, but if you don’t ask the question, you can’t know the answer!
Most of the complications of radial Keratotomy are fairly low in incidence and include things we would expect in any eye surgery such as scarring, misplaced incisions, blurred vision, starburst effect, ineffectiveness of the surgery, perforation of the cornea, and infection. These complications have been shown to be fairly rare, but there is no way to predict who will have these problems.
The major and most controversial finding, however, and the biggest long term problem for radial Keratotomy is the finding that 43% of RK patients had unstable, variable vision for at least 10 years after surgery! Many showed what is called progressive hyperopia, which means that the vision slowly progressed from "corrected" nearsightedness to farsightedness over time, leading to the need for glasses!
This finding also put the success rate statistics into doubt, since perfect results at one year could be poor results at year 5 or 10!
SINCE THE ADVENT OF EXCIMER LASER VISION CORRECTION, RK HAS VIRTUALLY DISSAPPEARED AND IS OF HISTORICAL INTEREST ONLY!