|Radial and Astygmatic Keratotomy: How the Surgery is Performed|
How is the surgery performed?
A thorough routine evaluation including measurement of the uncorrected focusing error after contact lenses have been out for a minimum of one week is the first step in preparing for this procedure. Included in the work-up is a test called Corneal Topography. This is a computerized evaluation of the corneal surface which produces a two or three dimensional map to disclose any unsuspected irregularities. Such irregularity could have an impact on the predicted surgical outcome.
Following this evaluation, the surgeon will then consult one of a number of surgical databases that will help him to determine how many incisions will be required to correct the myopia and how long each incision should be. In general, young patients require more incisions of greater length to correct a similar amount of myopia than older candidates.
The procedure is usually performed upon one eye at a time: in a sterile surgical outpatient setting. Anesthesia is limited to topical numbing drops in combination with mild sedative (i.e., Valium) given by mouth one hour prior to surgery.
Under microscopic guidance, the surgeon will first measure the thickness of the cornea using an instrument called an ultrasonic pacchymeter. This instrument can record the crucial measurement of corneal thickness using sound waves. A diamond micrometer blade is then precisely set to this thickness measurement with a specially adapted micrometer microscope A desired optical zone is then marked concentric to the pupil and visual axis. It is from this optical zone that the desired number of incisions (either 4 or 8) are placed using the preset diamond blade. The procedure is painless and lasts approximately 5 to 10 minutes after which the eye is patched and antibiotic drops administered.
Is the surgery painful?
After the surgery is completed most patients report only mild discomfort easily relieved with presciption pain medications. In the days which follow there can be occasional foreign body sensation.
What is the expected outcome of surgery - the prognosis?
In a recent retrospective study 98% of Radial Keratotomy patients (-1.00 to -7.00) achieved uncorrected acuity of 20/40 or better (driving acuity). Of these 30% were 20/20 or better. Therefore a candidate can expect tremendous visual improvement, sufficient to obtain goals of excellent uncorrected visual function for most activities, however, many patients might occasionally require use of spectacles for best vision after surgery.
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