|Radial and Astygmatic Keratotomy: Basic Information|
|What is Refractive Surgery?
Refractive surgery refers to a family of new surgical procedures designed to produce better eye focus with less dependence upon glasses or contact lenses for near-sighted, far-sighted, and astigmatic individuals. This field is one of the most exciting and intensively studied within modern ophthalmology, offering patients the realistic prospect of safe, effective and significant visual improvement.
Historically, ophthalmologists have long performed refractive surgery. Procedures which have an influence on either of the eye's natural focusing elements--the cornea or the internal crystalline lens, will have an impact on how well the eye can focus. Cataract surgery and corneal transplantation are therefore also members of the family of refractive surgical procedures performed routinely by ophthalmologists every day.
What is Radial Keratotomy?
Radial Keratotomy is the original and forefather of all incisional refractive surgical procedures. Originally described in the 1930's by Dr. Sato, a Japanese investigator who noted that he could obtain significant improvement for myopic (nearsighted) patients by placing a series of internal radial (spoke-like) corneal incisions extending outwards from a central clear optical zone. These incisions caused the central cornea to flatten hence reducing myopia. Unfortunately, it was later determined that incisions placed on the Interior surface of the cornea were damaging to its integrity and led to clouding. Dr. Sato is credited with observing that the amount of correction obtained increased with depth, number and length of incisions.
Dr. Sato's work took root in the Soviet Union in the 1960s where the persistence of Dr. Svyatoslav Fyodorov provided evidence that the procedure could be made significantly safer when the incisions were placed deeply on the external surface of the cornea extending from a central optical zone. Using a standardized formula and steel surgical blades, Dr. Fyodorov produced remarkably predictable results. Interest for the RK procedure in the United States developed in the late 1970's leading to a national controlled prospective investigation of the operation--the PERK study. This study sanctioned by the National Eye Institute, proved Radial Keratotomy as a safe and effective means of reducing myopic refractive errors.
Modern developments in RK technology have made this procedure safer and much more predictable. Ultra thin diamond micrometer cutting instruments with blade depths set under microscopic guidance and several computer generated data bases to guide surgical decisions are now routinely used by refractive surgeons who have embraced Radial Keratotomy and offer it as one of a number of choices that exist for the myopic patient.
Who is a good candidate for Radial Keratotomy surgery?
Generally, an individual over the age of eighteen years with myopia of -7.00 or less is considered eligible for RK surgery. With RK surgery, the lower the amount of the myopia, the easier it is to achieve complete correction. With the advent of the use of the Excimer laser to correct myopia (see PRK below) most surgeons will therefore limit the use of RK to those patients with myopia of -4.00 or less. Less surgery is required to correct a lower amount of myopia hence the procedure is even safer for the patient.
Candidates should have no past history of inflammatory, infectious or degenerative conditions of the cornea. Prospective patients should have no history of autoimmune disease or diabetic retinal disease.
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