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.