I. A Practical Approach
LAWRENCE W. OOELL, MD AND PETER WYZINSKI, DSc, MD
Radial keratotomy is being considered by more and more teenage myopes who are unhappy with the pubescent worsening of their vision and are not satisfied by any kind of corrective lenses. Sawelson has operated on 19-year-old patients;1 Deitz, on 18year-olds;2 Shepard, on 17-year-olds;3 while Momose has performed radial keratotomy on patients as young as 5 years.4 We present our experience and opinions with radial keratotomy in teenagers. This is the first article that specifically considers this therapeutic option in this age group.
PATIENTS AND METHODS
From a population of approximately 5000 myopes operated on by a single surgeon (LO) from 1980 to 1988, every patient with adequate follow-up who was a teenager at the time of the first radial keratotomy was included in this study, a total of 27 individuals. The average patient was a 17-year-old-female who was using contact lenses for 4.25 diopters (D) of myopia. Age ranged from 14 to 19 years. Similar to the adult patients of the PERK study,5 our teenagers were 41% male, 89% white, and 60% contact lens users. Except for three patients, each teenager had 20/200 or worse uncorrected distance visual acuity when both eyes were open. All but one 14-year-old had bilateral surgery. Twelve other teenagers have had radial keratotomy here but they were not included in this report because of less than a 3 month follow-up period.
In these 53 eyes no pathology was present except for the refractive error, very mild amblyopia in two eyes, and the typical abnormalities secondary to contact lens wear. Preoperative visual acuity with correction was at least 20/25 in each eye. The spherical equivalent of the preoperative refractive error ranged from -1.75 to -16.88 D while the cylindrical component ranged from 0 to 4.25 D.
Reduction in Myopia Due to Initial Radial Keratotomy in 53 Eyes (diopters SE)
The goal was usually to eliminate all refractive error in both eyes to attain perfect distance vision, but not necessarily by a single operation. Operative parameters were chosen to correct about 90% of the refractive error in the first radial keratotomy so that overcorrection would be infrequent. During the 8 years of this retrospective study, improvements in instrumentation and surgical techniques were adopted as soon as they became available. The first case was done with a razor blade fragment adjusted to protrude 50 µp? less than the central corneal thickness. As confidence was gained, the blade was adjusted to protrude more. Deepening of incisions was usually done. For the most recently performed 66% of the eyes, a diamond blade was adjusted to protrude 30 or 40 µp? more than the central corneal thickness as measured by an optical pachometer.
All surgery was done on an out-patient basis in an operating suite using only topical anesthesia; teenagers were as cooperative as adults. The optical center of the cornea was marked with a ring while the patient fixated on the microscope light. The central surgery-free zone was 2.0 to 4.0 mm in diameter; no more than 16 radial incisions were performed on the eye at a sitting. All incisions were centrifugal. The cuts were irrigated with balanced salt solution containing gentamicin (Garamycin). Eleven patients elected to have bilateral radial keratotomy on the same day. Patching was not used. For the first postoperative week patients were instructed to use gentamicin 0.3% and fluorometholone 0.1% drops twice a day.
Touch-up operations were performed liberally for any patient desiring further improvement. Old incisions were not reopened; instead, new cuts were placed between the scars and frequently a smaller central clear zone was used. To determine the number of radial incisions and diameter of the central clear zone of a touch-up procedure, the amount of myopia reduction caused by previous operations was considered and age was disregarded. Forty-five touch-up surgeries were done on 28 eyes of 16 patients involving a total of 285 additional incisions.
Return visits were scheduled for the day after surgery, and at 3 weeks, 3 months, and annually, assuming no complications. To be included in this study, the time between a patient's last radial keratotomy and most recent examination had to be at least 3 months; follow-up averaged 22 months with a range of 3 to 54 months.
When we call to remind a patient of a follow-up visit, we are frequently told that he is seeing well and just too busy to come in for a check-up. If there is any suggestion of a problem, a limousine is sent or a doctor in another city is paid to examine the patient. There is never any fee for a follow-up examination or a secondary radial keratotomy.
Analysis of Data
Pertinent data from the charts was compiled in a computer database. The amount of myopia was taken as the spherical equivalent of the manifest refractive error measured subjectively using the cross-cylinder method in a dim lane. All patients had a noncycloplegic and a cycloplegic refraction preoperatively. All postoperative refractions are noncycloplegic because refractions through dilated pupils after radial keratotomy are not germane and are inaccurate.
Figure. Scattergram shows preoperative and postoperative spherical equivalents in 53 eyes. Open diamonds represent eyes in which astigmatism stayed the same or was reduced by surgery. Small closed diamonds represent eyes where astigmatism increased 0.75 - 1.00 D, Large black squares represent eyes where the astigmatism increased by more than 1.00 D.
Myopia was reduced an average of 3.69 D and cylindrical refractive error by 0.08 D. For the six eyes with more than 7 D of refractive error preoperatively, the average reduction in myopia and cylindrical refractive error were 9.19 and 0.04 D, respectively. For those eyes with less than 3 D of preoperative myopia, the figures were 2.15 D and 0.15 D, respectively. The results for individual eyes are shown in the Figure. Uncorrected binocular visual acuity was at least 20/60 in all patients and 20/25 or better in 85%. No patient wore contact lenses postoperatively. With centrifugal incisions, these reductions in myopia were achieved by the initial radial keratotomy: 1.98 D from six cuts at 3.5 mm; 2.70 D from eight cuts at 3.5 mm; and 5.37 D from 16 cuts at 3.0 mm. In the PERK study of older patients, four cuts at 3.5 mm reduced myopia by 3.66 D while eight cuts at 3.0 mm reduced myopia by 4.69 mm. There have been no infections, no lawsuits, no ruptured globes. Follow-up and treatment whenever indicated are continuing for all patients.
The worst overcorrection. The worst overcorrection was in a patient with a preoperative uncorrected visual acuity of 20/600 and refraction of: OD, - 5.25 -0.50 × 130 = 20/20; OS, -5.75 = 20/20. Because of undercorrection after the first radial keratotomies, each eye had a second operation consisting of eight radial incisions at 3 mm giving this result: OD, -2.00 -0.25 × 70 = 20/20; OS, -1.75 = 20/20.
Over the next 2 years refraction changed to: OD, +5.25 -4.75 × 102 = 20/15; OS, +2.25 -1.75 × 90 = 20/15. The patient reported monocular diplopia in the right eye and the uncorrected visual acuity in this eye was 20/50. The patient was surprisingly satisfied, but we anticipate that an additional operation may be necessary in the future (LW O'Dell, P Wyzinski, unpublished data, 1989). Uncorrected vision with both eyes open was 20/20 at the most recent examination.
Case TWo: Astigmatism.
Difficulty in controlling astigmatism was noted in a patient whose initial refraction was: OD: -4.25 -4.25 × 15 = 20/25; OS, -5.25 -3.25 × 166 = 20/25. A doctor in another city reported to us that she was getting along without glasses or contact lenses although her binocular vision was only 20/50 and her refraction was: OD, -1.00 -5.00 × 13 = 20/25; OS, -1.75 -2.00 × 150 = 20/30. We believe that this patient could benefit from touch-up procedures but she got married, moved, and has been impossible to locate.
Case Three: Use of Glasses Postoperatively.
The patient with the highest myopia in this series had the following preoperative refraction: OD, -14.25 -1.75 × 2 = 20/20; OS, -16.00 -1.75 × 175 = 20/25. Two keratotomies on each eye using a 2.0 mm diameter central surgery-free zone for the touchups eventually gave this result: OD, - 1.50 - 0.50 × 115 = 20/30; OS, -1.25 -0.50 × 35 = 20/40. In spite of glare at night and some fluctuation of vision, this patient was very pleased with her result; she was the only one requiring corrective lenses postoperatively and she wore them only at night.
In a few cases, one eye was left purposely 1 to 2 D undercorrected by the first operation to ensure permanent good near vision without correction. In young and adult patients "monovision" was generally well accepted. "Monovision" is a misnomer. The brain only suppresses foveal cones that cause a subjective sense of blurriness and stereopsis remains normal if the nondominant myopic eye is -2.00 D and the dominant eye is - 1.00 to +0.50 D. The symptoms of anisometropia are negligible until glasses are placed. Then, anisophoria and image size disparity do cause symptoms.
It is not always necessary to operate on both eyes during the teen years: sometimes a single conservative operation on the worst eye can permit a patient to function well for years. However, should the myopia worsen as time goes on, additional operations can be done as needed. Touch-up radial keratotomies work better than is generally appreciated. The judicious use of touch-up procedures can minimize the occurrence of overcorrection.
In the PERK study, 19-year-olds were rejected, but 21-year-olds were accepted.6 The young appreciate the freedom that normal vision gives. The case in this series with the most follow-up shows no sign of any problem (and happens to be LO's daughter). Refraction 5 1/2 years after her first radial keratotomy is: OD, 0 = 20/15 (dominant eye); OS, -1.25 = 20/15 (nondominant eye). For all teenage patients we required informed parental approval. Many of these parents were engineers who had personally experienced radial keratotomy themselves. Informed consent under these circumstances means that the surgeon feels comfortable with the whole family unit. Operating on both eyes at the same time eliminates the period of anisometropia, shortens the morbidity, and caused no serious side effects in this series.
Whether or not the cornea is more at risk from rupture after radial keratotomy is an open question. Teenagers probably heal more rapidly and better than older patients. If a rupture must occur, then an anterior break might have better chances of salvage than a posterior tear. One of our teenagers fractured her orbit in a motor vehicle accident without causing any damage to her eye. In over 12 000 radial keratotomies in patients of all ages over 9 years at this clinic, not one single globe has ruptured so far and no corneal transplants have been necessary.
Most myopes experience an insidious onset of the disease between ages 5 and 12, a relentless progression during their teen years, and an eventual stabilization of refractive error by the end of their 20s.7 Few teenagers enjoy wearing glasses and practically none of them look forward to the seasonal introduction of new eyewear styles. Reports from parents indicated that several of our patients became more extroverted and more active in sports, which is not unheard of, after radial keratotomy.8
Large numbers of teenage myopes use contact lenses9 and some even try orthokeratology.10 About 30% of new fits are in teenagers.11 The practical problems with contact lens wear are well known. Some teenagers cannot tolerate the chemical preservatives in the various soaking, cleansing, and wetting solutions. Then there are the life-long expenses of replacement lenses, insurance, pharmaceuticals, back-up glasses, and of course, the recommended regular visits to an eyecare professional. The cosmetic advantage is somewhat reduced by queer head positions, abnormal blinking, and eternally red eyes.
Contact lenses have a multitude of undesirable effects on the cornea,12 even in young and otherwise healthy patients.13 In addition to irreversible pathologic changes in the endothelial cells which may contribute to corneal decompensation at some future date,14 infectious keratitis is an immediate danger. Contamination of the contact lens care system caused a Bacillus subtilis corneal ulcer in a 19-year-old.15 Poor dispensing was blamed for a bacterial corneal ulcer in a 13-year-old16 and the use of disposable contact lenses may not be a panacea.17 Of the 208 cases of acanthamoeba keratitis reported to the Centers for Disease Control to June 1988, 25 occurred in teenagers (J Stehr-Green, May 1989, personal communication) and every one of them wore contact lenses! Acanthamoeba keratitis in four teenage contact lens wearers was treated by penetrating keratoplasty resulting in 20/200 or worse vision in two eyes.18 Clearly, a lifetime of contact lens wear beginning in the teen years has risks. Do the various eyecare professionals who promote contact lenses point out these hazards in the course of obtaining informed consent? We believe there are some teenagers for whom radial keratotomy would be a better solution.
1. Sawelson H, Marks RG. Three-year results of radial keratotomy. Arch Ophthalmol. 1987; 105:81-85.
2. Deitz MR, Sanders DR, Marks RG. Radial keratotomy: an overview of the Kansas City study. Ophthalmology. 1984; 91:467-478.
3. Shepard DD. Radial keratotomy: analysis of efficacy and predictability in 1,058 consecutive cases. Part I: efficacy. J Cataract Refract Surg. 1986; 12:632-643.
4. Momose A. Treatment of anisometropia with radial keratotomy. The Journal of the Kerato-Refractive Society. 1986; 2:14-16.
5. Bourque LB, Rubenstein R, Cosand B, et al. Psychosocial characteristics of candidates for the prospective evaluation of radial keratotomy (PERK) study. Arch Ophthalmol. 1984; 102:1187-1192.
6. Waring GO III, Lynn MJ, Culbertson W, et al. Three-year results of the prospective evaluation of radial keratotomy (PERK) study. Ophthalmology. 1987; 94:1339-1354.
7. Curtin BC. The Myopias. Philadelphia, Pa: Harper & Row; 1985:40-44.
8. Shaffer J. Refractive surgery: emotional aspects. In: Nordan LT, ed. Current Status of Refractive Surgery. San Diego, Calif: CL Printing; 1983:66-68.
9. Hales RH. Cosmetic CL fitting in the young patient. Contact Lens Forum. 1987; 8:36-37.
10. Paige N. Why ortho-K? Contact Lens Forum. 1985; 11:65-67.
11 . Bennett I. Survey shows RGP's gain ground, extended wear use is still low. Contact Lens Forum. 1989; 1:75-78.
12. Schoessler JP. Contact lens wear and the corneal endothelium. J Am Optom Assoc. 1987; 58:804-810.
13. Orsborn GN, Schoessler JP. Corneal endothelial polymegathism after the extended wear of rigid gas-permeable contact lenses. Am J Optom & Physiol Optics. 1988; 65:84-90.
14. MacRae SM, Matsuda M, Shellans S, Rich LF. The effects of hard and soft contact lenses on the corneal endothelium. Am J Ophthalmol. 1986; 102:50-57.
15. Donzis PB, Mondino BJ, Weissman BA. Bacillus keratitis associated with contaminated contact lens care systems. Am J Ophthalmol. 1988; 105:195-197.
16. Spindel GP, Perry HD. Serious corneal complications associated with extended-wear soft contact lenses for myopia. Ann Ophthalmol. 1986; 18:141-143.
17. Parker WT, Wong SK Keratitis associated with disposable soft contact lenses. Am J Ophthalmol. 1989; 107:195.
18. Cohen EJ, Parlato CJ, Arentsen JJ, et al. Medical and surgical treatment of Acanthamoeba keratitis. Am J Ophthalmol. 1987; 103:615-625.
From the Northwest Eye Center, Eugene, Ore.
Reprint requests: Peter Wyzinski, DSc, MD, Northwest Eye Center, 1700 Valley River Dr, Eugene, OR 97401.
Received: January 25, 1989
Accepted: August 2, 1989
II. A Dubious Idea
RICHARD S. SMITH, MD
Since its beginnings in the United States in 1978, radial keratotomy has survived major controversies and critical studies by many centers. While many valid questions remain, the operation continues to be performed. The PERK study, as well as others1'4 substantiate that: 1) this is an effective operation for moderate myopia; 2) in the hands of a careful surgeon it is quite safe, although complications have been reported5,6; and 3) endothelial cell loss, a major early concern, is acute, minimal, and non-progressive. The principal remaining objections are the lack of predictability in individual patients and the argument that alternative methods for the correction of ametropia are inherently more safe.
Another issue is raised by the suggestion of Wyzinski that this operation may reasonably be performed on patients in their early teenage years. Many radial keratotomy surgeons would disagree with this position. There are a number of reasons for such objections, including the following: 1) issues of informed consent, 2) medical-legal questions, 3) rationalization of the need for surgery at an early age, 4) problems related to maturity of the eye and wound healing, and 5) changes in the stability of corneal and lenticular refraction and increases in axial length which occur during teenage years. Briefly stated, it is our contention that all of these objections make performance of radial keratotomy inadvisable in this age group.
Although the age of maturity varies in different states and for different issues, unemancipated minors cannot give informed consent for surgical procedures. Children are not expected to have the knowledge and long-term perspective of adults, so their perceived short-term needs are often in conflict with wise decision making. The issue is also complicated by parental desires and perceptions. During the 9 years that I have performed radial keratotomy, I have seen a considerable number of children in their midteens brought in by parents whose motivation to have radial keratotomy performed on their child centered around cosmetics, self-image and social status. In such a situation, the parents' concerns may keep them from making a reasonable decision, based on medical facts.
I have been asked to do radial keratotomy in order to give uncorrected vision that will allow a teenager to meet the vision standards of the armed forces, particularly the Air Force. At this time, a prior radial keratotomy is an absolute disqualifier as far as the Department of Defense is concerned. In two cases I have been unsuccessful in appealing this rule in individuals who had radial keratotomy performed elsewhere.
Another important issue is the medical-legal problem related to surgery in teenagers. There are cases on record in which children have brought suit against their parents and their surgeon for surgery performed. A much larger concern, however, is the issue of community standards. The law has greatly expanded the definition of what constitutes community standards in recent years, to represent what is really a national standard.
Surgeons should be cautioned by the fact that nearly all articles in the medical literature refer to 18 as the minimum age. In the PERK study design, one of the major eligibility standards is an age of 21 or older. The PERK standards note that 21 is equal to or over the age of maturity in all states, and that individuals at this age are less likely to show progression of their myopia. Ophthalmologists who ignore these well-established community standards would place themselves in legal jeopardy.
MOTIVATION FOR RADIAL KERATOTOMY
What is the rationale for doing radial keratotomy in the first place? Generally accepted reasons include a desire to be free from dependence on corrective lenses for normal visual function, occupational needs, contact lens intolerance, restricted visual field for optical reasons in higher degrees of myopia, spectacle discomfort, and a desire to change perceived personal image. If we are to do radial keratotomy in teenagers, we must apply the same criteria for surgical selection as we do for adults. Only the last of these reasons provides much of a rationale for doing the surgery in this young age group. Occupational needs are not a consideration.
While the issues of lens and spectacle problems occur in teenagers, these are certainly not strong reasons to rush into surgery for the sake of a few years of potential good uncorrected vision. Self image is a problem of paramount importance to teenagers. However, this is an insufficient reason for proceeding in the face of other objections. All of us who have teenage children know how difficult it is for them to wait for anything. A wise parent knows that there are times when such urgency must receive no for an answer. The surgeon should be guided by the same precepts.
CORNEAL WOUND HEALING IN TEENAGERS
The eyes of children and young teenagers do not react to accidental and surgical trauma in the same fashion as the adult eye. Corneal surgeons are well aware that wound healing progresses more quickly and that corneal vascularization is more prone to occur in the young. The more rapid healing of wounds might well result in a lesser effect from surgery. This is reflected in the well-known fact that the effect of a given amount of radial keratotomy surgery tends to increase with age.
In accidental trauma, penetrating keratoplasty, and epikeratoplasty the rapid healing and neovascularization lead to earlier suture removal in teenagers than in adults with a similar problem. Some authors have reported incision vascularization following radial keratotomy. The risk of this occurring in children is probably higher.
ANESTHESIA IN TEENAGERS
An ancillary surgical problem in children is that of anesthesia. In adults, I have been able to do over 700 radial keratotomy operations using only topical anesthesia. This is possible because adults tend to be wellmotivated and cooperative. The risk of movement during surgery might encourage some surgeons to consider general anesthesia in children, with all its attendant risks - another reason to avoid this elective surgery in teenagers.
STABILITY OF REFRACTION
The final issue to be considered is that of changes in corneal and lenticular refractive power and in axial length as the eye grows toward maturity. The reason for selecting age 18 to 21 years as the lower cutoff for case selection is the fact that many eyes have not reached their mature state before this age. A study of 628 boys between the ages of 3 and 15 demonstrated a decline in hyperopia, a decrease in mean corneal power, a considerable decrease in mean lenticular power and an increase in axial length. 7 None of these changes had ceased by the end of this study. While changes are conceded to be greatest before the age of 10, it is most important to realize that these changes continue into the teenage years. Duke-Elder8 notes that in many cases final maturity does not occur until age 21.
Sorsby9 found that only 35% of myopes remain stable prior to age 20, while the remainder continue to progress during growth and maturity. So-called progressive myopia may continue to show changes beyond the age of 20.
What are the implications of these well-documented changes in refraction that occur during the teenage years? While it might be safe to operate in some instances, say at age 15, there is no way of predicting whether there will be progression of myopia after surgery.
If this occurs, it might be necessary to subject the child to further surgery. Depending on the initial amount of surgery, progression of myopia might leave the surgeon without the surgical latitude to do the amount of surgery needed to recoup emmetropia. Thus, the opportunity to give the patient the desired effect might be irretrievably lost.
CONTACT LENS RISKS
The question may be asked as to the relative risks of radial keratotomy versus contact lenses. It is an accepted fact that there is an active risk of infection by bacteria, fungi, and amoebae in contact lens wearers. The risk appears higher in those who use extended wear lenses. However, the problems already noted with regard to radial keratotomy in teenagers do not recommend it as a substitute for contact lenses in teenagers.
My constant policy has been to refuse to do radial keratotomy on patients younger than the age of 18. In the 18 to 22 year age group, my first question to the patent and parents has been whether a change of glasses has been necessary in the preceding 18 months. If the answer to this question is yes, then I advise waiting for an additional 9 to 12 months before proceeding with radial keratotomy. I feel that the ethical, legal and biological reasons for caution are cogent. Nothing is lost by waiting; the safety and ultimate satisfaction of the patient may be gained.
1 . Waring GO, Lynn MJ, Culbertson W, et al. Three-year results of the prospective evaluation of radial keratotomy (PERK) study. Ophthalmology. 1987; 94:1339-1354.
2. Smith RS, Cutro J. Computer analysis of radial keratotomy. CLAO J. 1984; 10:241-248.
3. Neumann AC, Osher RH, Fenzl RE. Radial keratotomy: a comprehensive evaluation. Doc Ophthalmol. 1984; 56:275-301.
4. Sawelson H, Marks RG. Five-year results of radial keratotomy. Refractive and Corneal Surgery. 1989; 5:8-20.
5. Binder PS, Waring GO III, Arrowsmith PN, Wang C. Histopathology of traumatic corneal rupture after radial keratotomy. Arch Ophthalmol. 1988; 106:1584-1590.
6. Glasgow BJ, Brown HH, Aizuss DH, Mondino BJ, Foos RY. Traumatic dehiscence of incisions seven years after radial keratotomy. Am J Ophthalmol. 1988; 106:703-707.
7. Sorsby A, Sheridan M, Leary GA. Refraction and its components in twins. Med Res Counc Spec Rep Ser. 1962; 303:1.
8. Duke-Elder S. The Practice of Refraction. St Louis, Mo: CV Mosby Co; 1954:82-83.
9. Duke-Elder S. System of Ophthalmology. St Louis, Mo: CV Mosby Co; 1970; 5:267-268.
From the Department of Ophthalmology, Albany Medical Center, Albany, NY.
Supported in part by an unrestricted grant from Research to Prevent Blindness Ine, New York, NY.
Reprint requests: Richard S. Smith, MD, Department of Ophthalmology, Albany Medical Center, Albany, NY 12208.
Received: June 14, 1989
Accepted: July 28, 1989
Reduction in Myopia Due to Initial Radial Keratotomy in 53 Eyes (diopters SE)