SURVEY OF OPHTHALMOLOGY
VIEWPOINTS
VOLUME 28 - NUMBER 2 * SEPTEMBER-OCTOBER
1983
GEORGE 0. WARING III, EDITOR
Radial Keratotomy Editor’s Comment. Radial keratotomy
is a paradigm of modern ophthalmology in America, both scientifically and sociologically. Scientifically, it is one of the refractive keratoplasty procedures that have pushed ophthalmic surgery from the now commonplace world of microsurgery to the more accurate sphere of micronsurgery, and from the customary challenge of surgery on eyes that have pathologic abnormalities to the more novel surgery on eyes that are structurally normal. Sociologically, patients see radial keratotomy as part of omnipotent medicine’s brave new world. If the modern physicians can transplant hearts and keep man alive on the moon, surely they can devise operations that eliminate the need for spectacles and contact lenses. Many ophthalmologists perceive the procedure as part of the accelerating spiral of technical advancement that captures the physician on a breathless treadmill ofacquiring the latest skills and that breeds a subtle anxietey reflected in the unspoken feeling, “I missed out on phako; I missed out on IOL’s; I ain’t missin’ out on radial K.” While the principles underlying radial keratotomy have been known for almost a century, recent advances in refractive keratoplasty and instrumentation have made it an attractive procedure for treating nonprogressive myopia and some types of astigmatism. After the initial wave of enthusiasm, investigators have settled down to the exacting task of identifying and controlling the variables that could make radial keratotomy an accurate and predictable surgical procedure. In this pair of viewpoints articles, Dr. Bores who brought radial keratotomy to America, and Dr. Stark, who serves as Chairman of the Ophthalmic Devices Section of the Food and Drug Administration emphasize both the promises and problems of radial keratotomy. GEORCE 0. WARIN<; III (Surv Ophthalmol 28:101-l 11, 1983)
Key words.
I.
myopia
l
radial keratotomy
9 refractive keratoplasty
II. A Risky Procedure of Unproven Longterm Success
Safe, Efficacious Way to Correct a Handicap
LEO D. BORES, M.D., Scottsdale,
WALTER J. STARK, M.D., NEIL F. MARTIN, M.D., AND A. EDWARD MAUMENEE, M.D.,
Arizona
Wilmer Hospital,
A
Ophthalmological Baltimore,
Institute,
The Johns
Hopkins
Maryland
T
in the human existence has also changed. In the “early days,” the battle against disease was black and white. As medicine progressed, the subject of “preventative medicine” began to play a more important role. Now there is more emphasis on the “quality of life” and the human condition than ever before and procedures designed to modify human existence, such as genetic engineering, plastic reconstructive surgery, and refractive surgery of the eye are being developed. The justification for radial keratotomy and other
he fear of blindness is second only to fear of cancer as a public concern, according to surveys conducted by such organizations as the National Society to Prevent Blindness, and Research to Prevent Blindness, Inc. In response to public concern, there has often been considerable publicity in the lay press regarding marvelous or “miraculous” new techniques to replace time-honored forms of therapy for ocular problems. Some of these new methods may turn out to be worthwhile, while with others the risk may be too great. Recently, radial keratotomy has been proposed in press reports to the public as a “cure for myopia,”
(Continued on next page)
(continued on page 106)
s our medical and technological advanced, the place of medicine
skills
have
101
102
Surv Ophthalmol 28 (2) September-October
1983
refractive surgery is quite clear in my view. Myopia can truly be said to be a deviation from the norm. Many individuals have their myopia from birth; therefore, it is possible to classify myopia as a type of congenital anomaly. If one accepts the definition of “handicapped” to mean having a condition in which normal function is not possible without the aid of an external appliance, then these patients are indeed handicapped. The wearing of glasses seems so commonplace to all ofus that we pay no attention to it. Consequently, for years, the plight of the myope, and to a lesser extent the hyperope, has gone unnoticed and their problems unappreciated. Careful questioning of most myopes will reveal the same story - “I feel trapped with my glasses.” “I feel imprisoned by my vision. ” “I would like to escape, to be normal.” It is true that some individuals do not feel this way, but the fact of their handicap remains. Much like the person with paraplegia who “accepts” this handicap and functions within it as well as possible - perhaps even in good grace. This “acceptance” by some and the disregard of the problem by others does not alter the fact that the problem exists and is in need of solving.
Development
of Radial Keratotomy
In 1869, Snellen described methods for the correction of astigmatism and discussed the possibility of altering cornea1 curvature.16 It wasn’t until 1894, however, that Bates attempted to do just that by employing a method of unsutured wedge resections.’ In 1939, Sato reported a series of cases in which anterior and posterior cornea1 incisions for irregular astigmatism were performed.14 His work in this field culminated in his famous paper in 1953 in which radiating incisions, both anterior and posterior, designed to reduce spherical myopia were described.15 That he met with poor surgical results and unfortunate postoperative sequelae is well known;“’ that he met with partial success is generally overlooked. Others attempted to duplicate and improve on Sato’s work, especially Belyaev,6 Kio Tin,” and Yenaliev.” The first real breakthrough in the technique came with the work of Fyodorov6*’ and Durnev.4 They demonstrated, both in animal models and in humans, that significant changes of a permanent nature could be induced by performing partialpenetrating, radial cornea1 incisions externally. This work led to the present surgical procedure known as radial keratotomy. Radial keratotomy as it is performed today differs from the Sato operation in major respects. The Sato procedure was performed using surgical loupes for magnification. The incisions were made with special hand-honed knives designed for the purpose. The surgical technique required entry into the ante-
BORES rior chamber at three to four different sites. Incisions were then made through the endothelial surface from the edge of a constant 6 mm central optic zone to the periphery of the cornea. The knives were unguarded, necessitating that the incisions be made “free-handed” to an approximate depth of 50% of the cornea1 thickness. Additional incisions were then made from the exterior surface of the cornea for the same approximate depth. These were placed between the previously made internal incisions. There is no indication that pachymetry was performed. Yamaguchi et al” have estimated that 4050% of the endothelium was damaged at the time of the surgery. Slitlamp examination of these patients has shown that the depth of the cornea1 incisions is inconsistent and varies from 30-70% of the cornea1 thickness. In some cases, Descemet’s membrane is rolled up into “tubes” along the incisions.
Current Techniques
and Results
Fyodorov recognized the inadequacy of some of the early work and began in 1973 to apply some of his own thoughts to a surgical cure for myopia. Fyodorov’s procedure is performed using an operating microscope for magnification thereby providing better illumination as well as more precise optics. The blade used from the outset is a high carbon steel razor fragment held in a specially designed knife handle. The blade depth is set in reference to corneal pachymetry. The optical zone size is not an arbitrary 6 mm, but is varied in size (from 3 mm to 6 mm) depending upon certain factors. These factors are: 1) degree of spectacle myopia, 2) degree of corneal curvature, 3) cornea1 diameter, 4) cornea1 “rigidity,” 5) pachymetry, 6) intraocular tension, and 7) number of incisions. Deepening of the peripheral portion of the incisions is performed in some cases. Whereas 3.5 diopters (mean, 1.2 diopters) of myopia is the most correction obtained by the Sato procedure, with the Fyodorov technique 14 diopters have been corrected, with the mean correction approaching 6 diopters. 6 Whereas approximately 7580% of the 200 + patients undergoing the Sato procedure developed cornea1 edema an average of 20 years after the operation9 none of the estimated 30,000 patients who have had radial keratotomy to date have been reported to have developed this complication (some 347 having a follow-up period of at least seven years). Radial keratotomy has undergone significant changes since 1973. In 1979, I began to deepen the peripheral portions of the incisions in multi-steps, theorizing that this technique would result in an increase both in the degree of correction and permanency of the effect. The ultrasonic pachymeter was developed to increase the accuracy of the thickness
103
RADIAL KERATOTOMY TABLE Summary of Surgical
Results Group
Number
of eyes
Dates of surgery Eyes with final refraction + 0.50 D Eyes with final refraction 5 +0.75D Eyes with final refraction 2 -0.75D Average residual myopia Mean change in keratometry 3 mos post-op 12 mos post-op Change in keratometry/refraction Uncorrected visual acuity post-op 20/20-20125 20/3o-‘LO/40 20/50-20170 Less than 20170 Data taken from Bores Forum 1:24-27. 1982.
LD: Radial
1
One Bar or More After Surgery 1
Group
303 11/79-12/80 179(59%) O(O%) 124(41%) - 1.18D
97 4179-10179 24(25%) 3(3%) 70( 72%) -3.12D 3.09D 1.74D 1.21
4.79D 4.23D 4.23
25% 4% 44% 27% keratotomy.
45% 20% 21% 16% A progress
measurements and thereby the accuracy and depth of the blade settings. Micrometer blade holders, allowing precise incremental blade settings, followed close on the heels of the ultrasonic pachymeter. The results of these and other modifications have been greater and lasting cornea1 flattening. In 198 1, I reported a series of cases whose myopia ranged from 2 to 11 diopters.3 A summary of the results appears in Tables 1 and 2. The three groups described are characterized as follows: Group I - Age range was 18-63 years with a mean age of 28. The blade used was a Beaver #76a. Sixteen single-depth incisions 75% of the paracentral optical pachymetry were made. Group II - Age range was 18-53 years with a mean age of 29. A Beaver #76a blade was used and 16 incisions were made. In this group, the incisional depth was selected by subtracting .05 mm from the paracentral optical pachymetry. In some cases, deepening of all incisions from the midperiphery was done. Group III -Age range was 20-5 1 with a mean of 29.5. In these cases, “Sputnik” brand razor fragment set by adding 10% to the paracentral ultrasonic pachymetry. Some of these cases had peripheral deepening as needed. All optical zone sizes were selected using the Fyodorov formulas themselves (or, in the case of early surgeries, from nomograms derived from the formulas). Approximately 70% of the patients reported obtained a postoperative unaided visual acuity of 201 40 (0.50) or better for most of the day. A significant percentage of the remainder had considerable re-
2
report
Group
3
150 l/81-7/81 96(64%)
1( I % ) 47(31%) - 0.88D
Tootal 550 299(54%) 4(0.05%) 241(44%)
6.32D 5.44D 5.44 54% 23% 15% 8% of the American
experience.
Ophthalmol
duction in their myopia, such that most patients reported an improvement in unaided visual acuity. Several of the patients in my most recent series (to be reported) have demonstrated up to a three-line improvement in visual acuity with spectacles after surgery. As with any surgical procedure, complications (both severe and mild) can and do occur. The major sequelum of the surgery seems to be increased night glare. This occurs in the majority of patients and lasts for a variable period of time. The severity of this glare diminishes markedly at three to four months and subsides gradually thereafter, with some patients still reporting noticeable “star tigures” after fourteen months. Most of the complaints of glare after three months is elicited rather than volunteered. Most patients describe it as being no worse than that from contact lenses. Ongoing work with the Miller-Nadler glare-tested is shedding some light (no pun intended) on this problem. The next most commonly heard postoperative complaint is that of fluctuating vision from dawn to dusk. This fluctuation has been measured in a number of cases. The highest cornea1 change recorded in my series was 3.37 diopters in a twelve-hour period. The mean is approximately 2 diopters. An occasional “normal” patient who has never worn contact lenses or undergone surgery has also shown fluctuations in vision. Several of these have also been measured. The highest cornea1 change recorded was 2.87 diopters in a twelve-hour period. For the most part, fluctuations of cornea1 keratometry from dawn to dusk never exceed 1 diopter in controls (the mean being .62 diopters). Hysteresis of the cornea
104
Surv Ophthalmol
28 (2) September-October
1983
BORES
TABLE 2 Postoperative
Visual Aruit_v Results
(% of Patients)
Group 1 Apr
1979-Ott
Preoperative refraction - 2.OC- - 4.00D (262 Pts) 20/20-20125 20/30-20140 20/50-20170 Less than 20170 Preoperative refraction -4.25--6.OOD (156 Pts) 20/2@20/25 20/30-20140 20/50-20170 Less than 20170 Preoperative refraction -6.25-10.00/D (132 Pts) 20/2c-2012.5 20/3~20/40 20/50-20170 Less than 20170 Data taken from Bores Forum 1:24-27, 1983
LD: Radial
Nov
1979-Dee
1980
Jan
Group 3 1981-July 1981
70 25 3 1
87 1 3 0
93 3 4 0
10 9 22 27
64 16 2 18
71 14 11 4
10 18 13 57
18 20 39 22
25 33 32 11
keratotomy.
begins to return toward normal levels at 30 to 45 days, with most being close to the normal range at four to six months postoperative. One patient in my series still shows significant cornea1 changes after three years. Because the goal during surgery is to bring the incisions as close to Descemet’s membrane as possible, concern for the endothelium has always been present. This concern was increased by the report of Hoffer et al who showed a mean cell loss of IO%.’ Bores et al3 reported a mean cell loss of 6.3% at one year. Rowsey corroborated this finding, reporting a mean loss of 6.9% with no evidence of progression at 12 months.13 Of the 30,000 plus cases estimated to have been performed in the Soviet Union and here in the United States to date, only nine major complications are known to have occurred. These are: 1) one case of endophthalmitis following microperforation of the cornea;8 2) three cases of cataract formation occurring under the same circumstances (one demonstrating frank capsule injury);* 3) four cases of deep stromal keratitis occurring in the central optic zone (all assumed to be related to previous herpetic keratitis and all responsive to steroid therapy);“: and 4) one case (not related to the surgical procedure itself) in which blindness occurred following a retrobulbar injection of an anesthetic. *Schachar R: Radial keratotomy. Paper presented refractive Society, New Orleans, 1981 :Dietz M: Personal communication
Group 2 1979
to the Kerato-
A progress
report
of the American
experience.
Ophthalmol
As the earlier dire predictions have withered and fallen by the wayside, the detractors have reached farther and farther afield for negative comments about the surgery - one of the commonly heard complaints being that the surgery is “not at all predictable.” While at the outset this argument may have had some merit, it too is beginning to fade in the light of recent work. Fyodorov and co-workers with a much longer experience and more cases have stated that by evaluating ten factors (the seven previousy mentioned plus age, sex, and the axial length of the eye), it is possible to predict the outcome in 92% of the cases.* Using seven factors, I have been able to predict the outcome in approximately 75% of the cases, plus or minus one diopter, in a dioptric range of 4 to 7 diopters. It should not be alarming to anyone that as many as 11 different factors may have to be considered in an effort to predict the outcome. After all, this is a new type of surgery which is truly “microsurgery,” and all of the answers are not in.
Opinion One continually hears the comment that radial keratotomy is not new. Furthermore, it’s been done before and it didn’t work. But then the wheel is not new either, its been done before, lo these many years. However, no one confuses the earlier product with our new and modern wheel and I doubt that anyone would care to return to the earlier design. I *Fyodorov
S: Personal
communication
105
RADIAL KEKATOTOMY would hope that this realization on the part of detractors, well-meaning and otherwise, would end the discussion and let us get on with the task at hand - namely, refining the “wheel.” It is a sad commentary on our human species that the “NIH” (“Not Invented Here”) syndrome is so pervasive. It seems that there is a tendency for those of the Homo sapien persuasion to look with suspicion upon anything not personally created. While in the past this attitude undoubtedly had great survival value, its usefulness has diminished in a cooperative society. Some have developed this tendency to a fine art and have carried it to the extreme of telling others how to order their lives (the Carrie Nations of the world). Such propensity is defended under the guise of “teaching” the “great unwashed” the error of their ways. Pronouncements by such individuals are taken by their fellows to be holy writ and are acted upon with religious zeal. The common denominator here is the profound belief that “They” are incapable of rational thought while “We, the Teachers” are the only possessors of the qualities of wisdom and truth. There are myopic individuals who, for whatever reason, are unable to function with the “crutches” they have been saddled with. Certain vocational positions in life are closed to them because of their aflliction and for some of these patients it’s a case of “Catch-22.” They have the myopia and therefore they are not qualified for the position, and if they have the myopia surgery they are not qualified either. The reason they are given, accompanied by a lot of doubletalk, is: “We don’t know what’s going to happen in the future.” I submit to you that I don’t know what is going to happen in the future either. My crystal ball is no better at predicting the future than anyone else’s (and I have two, one for consultation and the other for a second opinon). We have sufftcient experience with more severe cornea1 trauma than that produced under controlled circumstances by an experienced microsurgeon. We have, all of us, in our experience seen individuals who have sustained trauma, some twenty to thirty years prior to our examination. Many of these cases, even in the face of tissue loss, have corneas that have remained stable and clear and some vision is obtained through the use of contact lenses, or perhaps even spectacles. Once injured in these ways, these corneas retained their altered charcteristics. As a matter of fact if this were not the case these individuals would not need contact lenses to smooth out the irregular cornea1 surface; nature would have done it for them through “cornea1 memory.” If there was “cornea1 memory,” all of these corneas would have returned to normal. The fact is that incisions into the cornea of sufficient
depth allow internal pressure to remold the cornea1 surface, such that when scarring occurs the cornea1 curvature is, for the most part, permanently altered. Cornea1 refractive surgery is here to stay. Radial keratotomy, a form of refractive surgery, is a safe, simple, efficacious method of altering permanently - cornea1 curvature in the myope. It has been shown to be almost as effective, and certainly a lot safer, than other methods presently being employed. The technique has become more refined and the reported endothelial cell losses are very low. This surgery has an exciting potential both from a medical as well as a sociological standpoint. I would hope that all ophthalmic surgeons will join me in a cooperative effort to pool the data to study, to perfect, and to polish this most interesting “wheel.”
References 1. Bates WH: Suggestion 2.
3. 4.
5.
6. 7.
8.
9. 10.
11. 12. 13. 14. 15. 16.
17.
18.
of an operation to correct astigmatism. Arch Ophthalmol 23:%13, 1894 Belyaev V: Some Possibilities of Treatment of Hish Myopia: Thesis of Reports of the Third All-Russian Congress of Ophthalmologists, Moscow 1975. Bores L, Myers W, Cowden J: Radial keratotomy: An analysis of the American experience. Ann Ophthalmol 13:941-948, 1981 Durnev V: Decrease of cornea1 refraction by anterior keratotomy method with the purpose ofsurgical correction ofmyopia of mild to moderate degree. Proceedings of the First Congress of Ophthalmology of Transcaucasia, Tbilisi, 1976, pp 12%132 Durnev V, Ermoshin A: Determination of dependence between length of anterior radial nonperforating incisions of cornea and their elTectiveness. Transactions of the Fiflh All-Union Conference of Ophthnlmolou. Moscow, 1976, pp 106-108 Fyodorov SN, Agronovsky AA: Longterm results of anterior radial keratotomy. J Ocul Ther Surg 1:217-223, 1982 Fyodorov SN, Durnev VV: Operation of dosaged dissection of cornea1 circular ligament in cases of myopia of mild degree. Ann Ophthalmol 11:1885, 1979 Gelender H. Flynn H, Mandelbaum S: Bacterial endophthalmitis resulting from radial keratotomy. AmJ Ophthalmol93:323, 1982 Hoffer K, Darin J, et al: UCLA clinical trial of radial keratotomy. Ophthalmology 88:72%736, 1981 Kanai A, Yamaguchi T, Yajima Y, et al: The fine structure of bullous keratopathy after anteroposterior incision of the cornea for myopia. Folia Ophthalmol Jpn 30:841, 1979 Kio Tin M: Scleral keratoplasty in treatment of progressive myopia. Vestn Oftalmol3:24, 1976 Nirankari V, Katzen L, et al: Prospective clinical study ofradial keratotomy. Ophthalmology 89:677-683, 1982 Rowsey J, Balyeat H: Radial keratotomy: Preliminary report of complications. Ophthal Surg 13:27-35, 1982 Sato T: Treatment of conical cornea (incision of Descemet’s membrane). Nippon Gankn Gakkni Zasshi 433:541, 1939 Sato T, Akiyama K, Shibata H: A new surgical approach to myopia. Am I Obhthalmol 36:823. 1953 Snelien H: 6ie’Richtunge des Hayptheridiana des astigmatishen auges. Albrecht eon Graefes Arch Klin Ophthalmol 15:199207, 1869 Yamaguchi T, Kanai A, Tanaka M, Ishii R: Bullous keratopathy after anterior-posterior radial keratotomy for myopia. Am J Ophthalmol 93:600, 1982 Yenaliev: Experience in surgical treatment of myopia. Vestn Optalmol 3:52. 1978
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