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Radial Keratotomy NEW HELP FOR PATIENTS WITH MYOPIA Doris C. Dodge, RN
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yopia, or nearsightedness, is an abnormal eye condition in which light rays from distant objects are focused in front of the retina instead of on it, so that objects are not seen distinctly. A comparison of a myopic eye to a normal eye can be seen in Figs l a and lb. For the thousands of people who have this usually hereditary disease, myopia is a handicap. Radial keratotomy (RK) can now correct myopia and astigmatism-uneven curvature of the cornea or lens, causing horizontal and vertical rays to be focusedat two differentpoints on the retinafor many patients. The procedure consists of making precise incisions on the surface of the cornea at determined depths and lengths. The myopic eye, which is too long, is shortened as the central curvature of the eye is flattened.
Doris C. Dodge,RN,is the charge nurse, depariment of ophthalmology,Hillcrest Hospital Mayfleld Heights, Ohio. She has a diploma in nursing from Huron Road Hospital Shoo1 of Nursing, East Cleveland Ohio. 214
The RK procedure was conceived in Japan about 30 years ago, but evolved and was modified in the USSR by Dr S. N. Fyodorov in Moscow. This relatively new procedure in the US has met with controversy and criticism by some ophthalmologists. Before surgical procedures are accepted as safe and effective methods of treatment in the US, extensive study is required. The needed research for radial keratotomy was undertaken by the National Eye Institute, Bethesda, Md, who sponsored the “Prospective Evaluation of Radial Keratotomy,” or PERK study, and who in part sponsored the “Analysis of Radial Keratotomy,” or ARK study. At our institution, the surgeon involved participated in the Kerato-Refractive Society research group. These groups devised specific methods of data collection and analysis to give surgeons protocols and methods to report results.’ Results of the PERK study were released late in 1984. The most frequently reported complication of the radial keratotomy procedure was undercorrection or overcorrectionof myopia. The appearance of epithelial cysts or abraded incisions has also been reported, although infrequently, and may have resulted from vigorous wound irrigation during surgery. Debris of red blood cells in the wound could occur as a result of incising into the sclera. In addition, astigmatism can result from asymmetry of the incisions or interaction with existing astigmatism. I think it is important to note that the success of this operation lies in the skill and ability of the surgeons.
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Fig l a Myopic eye. Light rays focus in front of the retina, resulting in blurred distance vision. I
Fig Ib. Emmetropic (normal) eye. Light rays focus on the retina.
Since 1981, I have assisted Martin A. Markowitz, MD, on approximately 700 radial keratotomy procedures at our hospital. For our patients, scarring has not been a problem. The incisions cannot be seen with the naked eye one day after surgery and can only be detected through a microscope. In the current literature, I found no reports of potentially vision-threatening complications such as bacterial keratitis, endophthalmitis, cataract development, or traumatic rupture of the globe.
Patient Selection
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he physician bases patient selection on factors such as the patient’s age (not younger than 18), degree of myopia, amount of astigmatism, stability of the myopia, and the absence of other ocular pathology. Results of routine tests performed in the office also influence patient selection and include visual acuity, refraction, keratometry to measure the corneal curvature, and pachymetry to measure
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thickness. Radial keratotomy can correct vision of between 20/80 and 20/1600 to 20120. The degree of. myopia is measured in negative diopters. A correction of 6 diopters is the amount generally achieved with the procedure and therefore, a patient with myopia measuring -6 diopters can expect excellent results. Some patients achieve even greater correction; one patient measured -12 diopters, but because she could not get enough correction with contact lenses and was forced to wear thick glasses, she decided to have the surgery. After RK, she was able to wear extended-wear contact lenses. Moderate degrees of astigmatism between one and 2.5 diopters can also be corrected with RK.
Preoperative Care
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f test results indicate the patient is a good candidate for surgery, he is given information about the desired outcome of the operation. Our surgeon uses pamphlets to explain this, as
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Fig 2. Instruments used for radial keratotomy procedure: (a) 25-gauge, 518 in needle, (b) optical center marker, (c) double fixation forceps, (d) depth gauge, (e) cellulose sponges, (jl balanced salt solution with 30-gauge imgating cannula, (g) imgating needle, (h) speculum, (i) diamond micrometer blade, 69 micrometer coin
gauge. well as an audiovisual tape that explains the details of the informed consent. Candidates for radial keratotomy are different from the typical cataract and retinalophthalmic patients; they are younger, totally dependent on eyeglasses or contacts, and are excited and highly motivated at the thought of being able to see without constant visual aids. Nursing care begins when the patient arrives in the walk-in-surgery department. After receiving a three-minute facial wash with chlorhexidine gluconate skin cleanser, the patient is usually given diazepam (Valium), the dosage of which depends on his level of anxiety and body weight. The OR nurse provides physical comfort and emotional support to the patient in a short period of time. The circulating nurse is aware that the patient cannot see without his glasses, so she explains in detail what she is doing. Holding the patient’s hand can be comforting and reassuring, and because he is usually anxious about the elective eye procedure, I also find it helpful to make a positive statement about living without glasses. Apprehension dissipates when I say, “Won’t it be wonderful to walk outside in the winter without fogging up?“ Or, for female patients, “Just think how nice it will be to be able to shave your legs 218
in the shower and not have to wear glasses.”
Intraoperative Care
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n preparing to assist on a radial keratotomy procedure, the operating microscope is positioned, the instrument set readied, and tetracaine 112% drops must be available for instillation. The instrument set includes various optical zone markers, a 30-gauge irrigating cannula tip, fixation forceps, speculum, a 25-gauge needle for marking the patient’s visual center, and a diamond knife (Fig 2). The diamond knife is extremely delicate, and great care must be taken in handling and cleaning it. The knife contains a retractable blade that has been honed from an industrial diamond. It has calibrations to set the desired blade length to deliver a cut at the depth that the surgeon has calculated. Precision is of the utmost concern in this procedure. The operating table is positioned with some flexion, with the backrest slightly elevated and the foot lowered to resemble a chaise lounge. A doughnut is used to stabilize the patient’s head. This position enhances relaxation and makes the patient comfortable. The majority of our patients require only local
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Fig 3. Marking of the clear zone, which will not be
incised.
and topical anesthesia, and the circulating nurse monitors their vital signs. At the surgeon’s discretion, a patient who has displayed considerable anxiety or who has requested an intravenous supplementary medication may be scheduled for local stand-by anesthesia. In this case, the anesthesiologist monitors the patient’s vital signs and starts an intravenous line for the administration of diazepam. The circulating nurse preps the patient with povidone iodine, and the scrub nurse drapes him for minor ocular surgery. The surgeon instills tetracaine 1/2% into the eye, and a lid speculum is put in place. If the patient tends to squeeze the speculum with his lid, the surgeon may inject a lid block. There are several things the nurse can do to facilitate this three-minute to eight-minute operation. If the patient is unable to relax, I ask him to take a few slow deep breaths and initiate another positive thought, or sometimes I divert his attention to the radio. The patient’s cooperation is essential when the surgeon is preparing to mark the optical center. He will ask the patient to focus on the filament in the light of the microscope. The nurse can describe the filament as looking like a comb or a coil. When the pupil constricts, the clear zone, which will not be incised, is marked first with a 25gauge needle, and then the zone marker is aligned
Fig 4. Diagram of marking of the clear zone.
with this dot and pressed onto the cornea with enough pressure to leave an indentation on the corneal epithelium (Figs 3 and 4). The clear zone is visible throughout the procedure. The globe is then grasped with a fixation forcep. Should the patient find this uncomfortable, the surgeon can inject a small amount of local anesthetic subconjunctivelywith a 30-gauge needle. For most Cases, we do an eight-cut procedure (Fig 5a), but depending on the patient’s age and degree of myopia, a 16cut procedure may be required. With the diamond knife seated at the optical zone mark, the surgeon makes the incisions in a radial fashion outward from the central clear zone (Figs 5b, 6, and 7). Another variance would be in the treatment of the astigmatic eye, where other combinations of numbers of cuts, as well as their placements, 219
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Fig 5u Diagram of 8cut procedure. Fig 5b. Side view of eye. Globe is grasped with fixation forcep, and diamond knife is drawn toward periphery of cornea.
Fig 6. Incision being made on the cornea in
a radial fashion.
may be used. These calculations are all made by the surgeon before surgery, and he reviews them before starting the case. Antibiotic drops are instilled in the eye after surgery, and then the closed eyelid is covered with three sterile pads secured firmly to prevent opening and closing of the eyelid for several hours. This is done to keep the patient comfortable after the operation.
Postoperative Care
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11 patients done under local anesthesia are returned to the walk-in surgery department after surgery. Those patients who have received standy-by anesthesia with intravenous sedation are taken to the recovery room, 220
Fig 7. Incisions are made outward from the clear zone.
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where they stay about one hour. They are then returned to the walk-in surgery department and discharged. The patient is given prescriptions for pain and sleep medications and is advised to take the medication and go to bed when he amves at home. This is recommended so that the patient will sleep through any discomfort he might experience in the immediate postoperative period. The patient is reminded to review the postoperative instruction sheet given to him at the physician’s office when the surgery was scheduled. Instructions include instilling eye drops, which are a combination of neomycin, polymyxin sulfate, and dexamethasone(Maxitrol), three to four times per day for the first month. The sheet also informs the patient that he may experience light sensitivity and glaring with night lights for between two weeks and two months, until his eyes have healed. Five hours after surgery, patients are permitted to remove the eye patch and can resume their normal activities. Some patients report discomfort while the eye is patched similar to having a piece of dirt under a contact lens, but most patients describe the feeling as only a scratchy, itching sensation. Once the patch is removed, discomfort subsides except for a dull ache which may persist
for as long as 24 hours postoperatively. There will only be serous drainage on the pad from tearing, which is normal. The patient’s eyeglass lens on the operative side should be removed from the frame.
One Week Later
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pproximately one week after the first eye surgery, the patient returns to have the other eye done. Many patients who had local stand-by anesthesia for the first eye elect not to have it with the second surgery. Anxiety is far less a factor after the first operation. In dealing with radial keratotomy patients, I have developed a great appreciation for their handicap. Intraoperative nursing care should include communication through careful, calm explanations and touch. A patient who is also my nursing colleague in the operating room describes her experience with the radial keratotomy procedure in the following article. 0 Note 1. D R Sanders et al, Radial Keratotomy (Thorofare, NJ: Slack, Inc, 1984).
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PERSONAL CASESTUDY Nancy R.Benjamin, RN
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hen I first heard about the radial keratotomy procedure in 1980, my first thought was, “It’s not for me!” Even though I had been wearing glasses or contact lenses since I was seven years old, I was satisfied with my hard lenses and saw no reason to have surgery on “healthy” eyes. Then things began to change. My hard lenses began to cause corneal edema, and I was advised to switch to soft lenses. The soft lenses were never a satisfactory option for me because they did not adequately improve my vision, and they were extremely fragile. I gave up the soft lenses in 1982, and after 20 years of wearing contact lenses, I returned to glasses. As anyone who works in surgery can attest,
glasses were quite a problem. They steamed up when I was scrubbed, slid down my nose, and were always in the way. Radial keratotomy began to seem more appealing. I knew of the wonderful results some of our first patients had gotten, so I began to investigate further. The physician explained the procedure and the chance of complications. My biggest worry was the short history of the procedure in this country. I also wanted to know what would happen 20 or 40 years from now. The physician explained that only 90% of the thickness of the cornea is cut (to the membrane of Descemet). Because the endothelial cells are not cut and there is no loss of aqueous humor, the globe of the eye remains intact, leaving little chance for permanent damage.
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