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RK is still a less expensive option for low myopia
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SCRANTON, Pa. — Although laser surgery is usually preferred over incisional surgery – by both patients and doctors – those patients with low myopia who want less expense may choose radial keratotomy (RK). "For someone who is looking for something relatively less expensive and quick, RK is something to consider for myopia less than 2.5 D," said Joseph P. Shovlin, OD, FAAO, of Northeastern Eye Institute here.
While incisional surgery techniques of the late 1970s are much improved, Dr. Shovlin believes laser surgeries are the better alternative.
Screening considerations
Dr. Shovlin noted that the preop work-ups for RK, laser in situ keratomileusis and photorefractive keratectomy are similar. The greatest difference between RK and other refractive surgeries is the greater need for an accurate measurement of the pupil with RK patients.
Dry eye and basement membrane disease are screened for as carefully as possible. "Sometimes, when we are not sure whether we might have a ‘leaky’ epithelium or basement membrane problem, we will swipe the anesthetized cornea with a twisted wisp from a cotton-tipped applicator to see how loose the epithelial attachment is," Dr. Shovlin said. "If it is loose, we steer the patient toward PRK."
Another effective technique may be using sequential fluorescein staining and watching for areas that gradually take up more stain.
Corneal topography is useful for detecting subtle presentations of keratoconus and similar disorders that would contraindicate surgical procedures.
The preoperative refraction is carefully performed. "We use 1% cyclopentolate either sequentially or in combination with 1% tropicamide," he said.
Dr. Shovlin emphasizes that RK outcome is influenced by age and gender. "This should be taken into account in the preoperative phase," he said. "There is less effect from the incisions as men age. Women’s healing responses may vary according to their hormonal life stage."
Healing response
After the surgery, bandage lenses are used only if there is a significant wound gape, Dr. Shovlin said. "That was more common in astigmatic corrections, but these wound gapes are less common now. Some of the healing responses to RK will be quite different. The chances of immediate postop infection are probably low if you’re using the right antibiotic," he said.
"The industry standard right now is fluoroquinolone until re-epithelialization. We typically use fluorometholone four times daily, at least initially."
He explains that he is a "strong believer in artificial tears in any refractive surgery. You’ve essentially wounded the cornea significantly, and it is releasing an inflammatory response," he said. Dr. Shovlin’s practice uses nonpreserved artificial tears.
Follow-up visits
"The surgeon or an optometric director will see the patient 1 day postop, then the referring optometrist sees the patient at 1 to 2 weeks postop. Then, patients are seen at 1 month, 3 months and then 1 year," he said. "On the first day postop, with the use of the steroids and minimal surgery, the eye looks relatively quiet. We want to see less epithelial involvement with time, and certainly by the 1-week visit the structural integrity should look pretty good. The incisions should be free of any significant debris, and no infiltrative process should be present at that 1-week visit. From there the eyes look pretty good."
With RK, there is no problem with haze forming over the visual axis. The central clear zone is kept no smaller than 3.5 mm.
When acuity is below expectations, corneal topography may be useful in identifying irregular astigmatism or the location of the optic zone in relation to the visual axis. Dr. Shovlin explains that, because of the fear of overcorrection, his practice’s protocol requires a repeat cycloplegic refraction prior to any enhancements.
There are several alternatives for avoiding or treating under- or overcorrections. "You can count on a greater number of enhancements with RK or incisional surgery," Dr. Shovlin said. "In fact, we often do it in a titrated or step-like fashion, because the worst thing you can have is consecutive hyperopia where a consistent overcorrection is found after the surgery."
Surgeons often use only four incisions or will perform an "RK-lite" or a mini-RK. "It’s just a few short incisions, and we would not correct more than 2.5 D of myopia or 2.5 D of astigmatism," Dr. Shovlin explained.
Dr. Shovlin feels strongly that ODs should look at outcomes analysis data. "We’re making a big push in our practice to be able to share this with our referring optometrists and potential patients."
For Your Information:
- Joseph P. Shovlin, OD, FAAO, may be reached at Northeastern Eye Institute, 200 Mifflin Ave., Scranton, PA 18503; (717) 342-3145; fax: (717) 344-1309; e-mail: JShovlin@aol.com. Dr. Shovlin has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.