The Correction of High Myopia
I submit that the plight of the high myopes is to the 1990s what the sufferings of the aphakics were to the 50s and 60s. Forty years ago, I could not understand why the profession as a whole mocked Harold Ridley's efforts to improve the lifestyle of cataract/aphakia patients. However, the battle has been won and it was proper for ASCRS to honor Ridley, Binkhorst, Epstein, Choyce, and Fyodorov in 1989 on the 40th Anniversary of Ridley's first operation. The fact that approximately 3 million intraocular lenses (IOLs) were inserted in 1991 is proof that we were correct and that the rest of the profession was unnecessarily cautious. That is how it is today with the high myopes. Their sufferings stem from the minification induced by high minus spectacle lenses and because contact lenses often fail them.
Their dependency on either spectacles or contact lenses inevitably lead to grave restrictions on their lifestyle, such as difficulties in holding a driving license, and problems in sporting and aquatic activities, all of which lead to a great sense of deprivation. Potentially extroverted characters become very introverted. As one of my patients said to me after liberation from 40 years of 20.00 diopters of myopia, "until now, I have always felt that there was a wall between myself and the outside world." Another patient, when asked if he was glad he had undergone the surgery, paused and then said "Mr Choyce, I cannot begin to tell you what these operations have * meant to me." Indeed, these patients are so elated by the results of the surgery that this in itself creates a problem of dealing with patient refusal should the surgeon, for any reason, advise removal of the device responsible for the happiness.
High myopia is a chronic degenerative disease. Many of the patients end up with very poor sight, and it is our professional duty, as ophthalmologists, - to maximize their visual potential during their active years. Let us now look at the ways in which this can be done.
There are two fathers of refractive surgery: Jose Barraquer of Bogota and Sato of Tokyo. Barraquer applied himself with great determination and expertise in sculpting the cornea in a way that became more and more complicated and, although successful in his hands, procedures such as keratomileusis are not ideally for the ordinary ophthalmic surgeon. One feels that, after 40 years, they would be more widely practiced to stand the test of time.
The next approach to be considered is extraction of the clear crystalline lens with insertion of a low-powered posterior chamber lens. This technique was pioneered by Verzella1 in Bologna, Italy, about 7 or 8 years ago. He has performed several thousand of these operations and claims excellent results with only a low incidence of serious problems such as retinal detachment (1%). The figures I have heard quoted are that Verzella has a personal series of seven thousand of which only about 2500 have actually been followed up (Neumann, personal communication, 1991). His colleagues in Italy suggest that the incidence of retinal detachment is perhaps rather higher than that claimed by Verzella. Be that as it may, this is a demanding technique requiring very considerable surgical expertise.
WHICH TECHNIQUES CAN WE RECOMMEND?
The use of corneal inlays made from high refractive index materials is a very tempting intellectual concept. This technology does not involve opening the eye, nor does it involve the use of the microkeratome. I pioneered the use of these devices in 1981, the material I chose being polysulfone which has a refractive index of 1.633. This was synthesized in 1965 by Union Carbide of New Jersey, was used quite widely in medical and paramedical spheres such as in orthopedic surgery, and as components of heart valves, in renal dialysis equipment, and as a shunt for the cerebro-spinal fluid in cases of hydrocephalus. Its optical properties were recognized by NASA when they selected polysulfone to be the material from which the visors of US astronauts were made (NASA, personal communication, 1976). I pioneered the use of polysulfone to correct aphakia with my Mark VQI-style lens. Ten implantations in 1980 caused no problems, so in 1981, I commenced using them as corneal inlays in high myopia.2 In the decade 1981-1990, 1 inserted 56 polysulfone corneal inlays made up of 41 for myopia ( - 7.00 to - 27.00 D) and 15 for cataract/aphakia (five primaries following intracapsular cataract extraction and 10 secondaries).3,4 I do not regard the use of polysulfone corneal inlays (PCIs) as being likely to take over from present-day techniques such as phacoemulsification/ ECCE and posterior chamber lenses for cataract, because such techniques are very successful but they might have a role to play in secondary correction of aphakia.
I always recognized that it might be necessary to provide PCIs with some perforations if the layers of cornea in front of the inlay were not to be starved of fluid and metabolites working through from the anterior chamber. However, initially, there did not seem to be a problem of this nature but, eventually, around 1985, it became apparent that the inlays would have to be equipped with microperforations, at least the outer part of them. This was because of two complications which arose in my cases: One was the development of increasing hyperopia as the patients' day wore on. That is, a few woke up in the morning emmetropic, 20/20 unaided; by noon, they would require +3.00 D to see 20/20 and by midafternoon + 5.00 D. This happened in three patients and keratometer readings during the day showed that this phenomenon was accompanied by flattening of the cornea overlying the inlay. The other complication associated with solid nonperforated PCIs was the development of opacification in the central part of Bowman's membrane in six cases. In three of these, comparatively minor injuries to the cornea led to nonhealing corneal abrasions which were treated by removal of the inlay and lamellar keratoplasty, thus returning the eyes to their preinlay state, ie the same refraction and the same visual acuity.
Polysulfone, with a glass transition temperature of 36O0C is a difficult material to work with, and equipping these inlays with microperforations has proved difficult to accomplish and they are not as yet available on a commercial basis. But a number of companies are at work on this problem and other high refractive index thermo-plastics are also being studied. However, I would not hesitate to use a polysulfone corneal inlay today, equipped with crude perforations around a central imperforated 3 mm, if the situation required it. For example, it may be useful in a patient in need of neutralization of high myopia, but whose eyes were not suitable for the next technique which is going to be discussed.
High Minus Anterior Chamber Intraocular Lenses
In the first phase, from the mid-1950s until the mid-1960s, only the fixed length, noncompressible, angle-supported, anterior-chamber implants were used, ie of a modified Strampelli type. It was not Strampelli who popularized them but Joaquin Barraquer of Barcelona.5,6 He was very enthusiastic about their use, and a number of surgeons including myself also used them. My series comprised 46 cases from the years 1958 to 1965. Although the immediate results were reasonably satisfactory, I discontinued using them in 1965, but when I reviewed those 46 cases 20 years later, 16 out of the 46 had developed serious complications such as glaucoma, cataract, and, finally, corneal decompensation. I was, therefore, surprised when this approach was resurrected by Baikoff, in 1987,7 who was at that time working in Nantes, Brittany, and later transferred to Marseille. Baikoff used the Kelman multiflex Mark II design with open flexible loops, which depended on a 4-point angle fixation and had high minus optics (Domilens, Lyon, France). Many hundreds of these ZB lenses were used including 11 by me. The results were very good, but serial endothelial cell counts cast an ominous shadow, the suspect area being the midperiphery of the cornea close to the somewhat prominent rim of the hypernegative optic. Accordingly, in 1990, the ZB lens was modified in three respects: 1) increasing the optic diameter from 4.5 to 5.0 mm, 2) flattening out the prominent rim of the optic, and 3) reducing the angulation of the footplate from 25° to 20°. Since October 1990, they have been in use, and I have used 31 to date.
My experience with anterior-chamber implants commenced in 1955 and can be summarized as follows. Although the fixed-length noncompressible Strampelli design required accurate sizing and a large inventory of lens implants had to be available at the time, I argued that they were likely to cause less disturbance in the angle than those with closedloop flexible supports (the Dannheim lens) which I never used. As of now, I have used over 5000 Choyce/Strampelli anterior-chamber implants, predominantly my eighth and ninth modification (the Mark VIII and Mark EX anterior-chamber implants [Rayner, Sussex, England; Coburn/Storz, Clearwater, Fia, USAI). I am still reviewing implantations performed in the 1950s and 1960s, as well as the 1970s and 1980s, with clear corneas and good vision (albeit with low <500 cells/mm2 endothelial cell counts). Previously, I warned the profession about the dangers of anterior-chamber implants with closed flexible loops because they permitted micromovement in the angle leading to chronic uveitis.8 Unfortunately, the profession - especially certain manufacturers - ignored my warnings, which were repeated in 198 1.9 Thus, the second generation of closed flexible looped anterior-chamber implants made their appearance commencing with the Leiske lens (Surgidev, Goleta, Calif) in 1977, the Azar 9 IZ (IOLAB, Claremont, CaHf) in 1981, the Stableflex lens (ORC, Azusa, Calif) in 1982, and several other examples which were responsible for a great deal of ocular pathology, notably the UGH syndrome, difficulty in explantation, the need for perforating keratoplasty, etc, all of which have been amply documented.10*13 Apart from the regrettable and unnecessary damage to patients' eyes (a bonus for corneal transplant surgeons and attorneys specializing in malpractice suits), a serious casualty was the profession's regard for safer anterior-chamber implants such as the Choyce Mark VIII and IX, the Standard Tennant Lens (Precision Cosmet) and more recently, open-looped implants with four footplate fixation, as exemplified in the Keimen Multiflex Mark II, from which is derived Baikoffs ZB and ZB5M lens.
All surgeons who have used the ZB and ZB5M lenses agree that the functional results are excellent and were it not for the suspicious cell-count findings, the technique would be regarded as eminently satisfactory. My opinion based on my experience of angle-supported, anterior-chamber lenses summarized above is that the concern over these declining cell counts is exaggerated.
In the 1940s and early 1950s, Sato in Japan did about 800 anterior and posterior radial keratotomies. Komura14 has reported that 70% of his patients subsequently developed corneal edema, presumably because of the trauma inflicted on the endothelium by the posterior incisions. Of considerable interest, however, is the fact that 30% did not develop corneal decompensation, although recent studies have shown very low cell counts of the order of 400 to 500 in most of those surviving with clear central corneas. Evidently, a low cell count is only one factor in the development of corneal decompensation and bullous keratopathy. The one insult that the endothelium will not tolerate without decompensating is movement within the anterior chamber of a device such as these lenses. There is no evidence to show that these lenses do move about once they have been inserted into the anterior chamber. Undoubtedly, in the original ZB lenses, the rim of the optic was undesirably close to the cornea endothelium, but this problem has been greatly lessened. I expect the vast majority of these lenses to last out the patients' lifetime. Also, if decompensation is threatened, it should be technically possible to remove the lenses, extract the crystalline lens, insert a low power posterior chamber IOL, and perform a penetrating keratoplasty either at the same time or subsequently, thus restoring the sight that would have been compromised by corneal decompensation.
Worst/Fechner Iris Claw Intraocular Lens
The second anterior-chamber implant with high minus optic which has been used, but not on quite such a large scale, is the Worst/Fechner iris claw (lobster claw) lens. Fechner, having inserted 123 of these, encountered cornea decompensation in four - two of these he considered was due to operative difficulties at the time of their insertion. Even so, he was sufficiently alarmed to discontinue their use. Another German surgeon, Krumeich, (personal communication, 1991) has used 70 of these lenses and is perfectly satisfied to date.
Silicone Disc Posterior Chamber Intraocular Lens
The third anterior-chamber implant to have been used in much smaller numbers is the silicone lens of Fyodorov, placed behind the iris in contact with the anterior lens capsule. Fyodorov himself seems content with the results, but Neumann (personal communication, 1991) who has inserted a few of these, experienced opacification of the anterior part of the crystalline lens in one and noted a tendency for the implant to become decentered. Clearly, more time is required before this approach can be put in the correct context.
There are welcome signs that the ophthalmic profession is at long last facing up to its responsibilities to those unfortunate enough to suffer from high myopia.
At this time, it is my opinion that the safest and most effective option is the use of the ZB5M anterior chamber implant inserted into phakic eyes, the updated technique devised by Baikoff and Domilens.
In the long term, the future probably lies with the use of corneal inlays using a high refractive index thermoplastic such as polysulfone.
1. Verzella F. High myopia: refractive lensectomy and posterior chamber implants. Cataract. 1985;2:25-27.
2. Choyce DP. Semi-rigid corneal inlays used in the management of albinism, aniridia, and ametropia. Acta XXTV International Congress of Ophthalmology, San Francisco, Calif, 1982. Vol 2, 1230-1234.
3. Choyce DP. The correction of refractive errors with polysulfone corneal inlays; a new frontier to be explored? Transactions of the Ophthalmologic Society of the United Kingdom. 1985;104:332-342.
4. Choyce DP. Highlights of Ophthalmology. 30th Anniversary Edition. 1988; 224-234.
5. Barraquer J. The use of plastic lenses in the anterior chamber: indications - technique - personal results. Transactions of the Ophthalmologic Society of the United Kingdom. 1956;76:537-549.
6. Barraquer J. Anterior chamber plastic lenses. Results of and conclusions from five years' experience. Transactions of the Ophthalmologic Society of the United Kingdom. 1959;76:303424.
7. Baikoff G. A Colour Atlas of Lens Implantation. Wolfe Pubfishing Ltd; 1991:chap 33:211-213.
8. Choyce P. Intraocular Lenses and Implants. London: Aft, HK Lewis & Co Ltd; 1964;chap 2:4-15.
9. Choyce P. The VIth Binkhorst medal lecture. Anterior chamber implants - past, present, and future. Journal of the American Intraocular Implant Society. 1982;8:42-50.
10. Hagan JC III. Complications while removing the IOLAB 91Z lens for the UGH-UGH + syndrome. Journal of the American Intraocular Implant Society. 1984;10:209-213.
11. Hagan JC III. A comparative study of the 9 IZ and other anterior chamber intraocular lenses. Journal of the American Intraocular Implant Society. 1984;10:324-328.
12. Hagan JC III. Comparative study of the 91Z and other anterior chamber intraocular lenses. Implants in Ophthalmology. 1988;2:148-150.
13. Apple DJ. Intraocular Lenses, Evolution, Designs, Complications, and Pathology. Baltimore, Md: Williams & Wilkins; Chaps 4 and 7. In press.
14. Komura A. J Cataract Refract Surg. In press.
D. Peter Choyce, MS, FRCS, FCOphth
From the Old Court Hospital, London, England.
The author has no proprietary interest in any research or materials presented within this article.
Reprint request should be addressed to D. Peter Choyce, MS, FRCS, FCOphth, 45 Wimpole Street, London WIM 7DG, England.
Received: May 13, 1991
Accepted: November 2, 1991
Comment: Paul U. Fechner, MD, Hannover, Germany
Peter Choyce states in his elegant article that I discontinued the Worst/Fechner iris claw lens with hypernegative optic in myopic phakic eyes for fear of inducing bullous keratopathy. This statement is only partially correct and needs qualification:
* I will not implant the lens unless the anterior chamber has a depth of approximately 3.6 mm or over.
* I did indeed not implant the lens since November of 1991. The reason was that I had only two cases (three eyes) requesting this surgery and into these eyes I intended to implant silicon lenses developed by Professor Fyodorov in Moscow, once they became available to me (1 did so recently).
* My interest in the Moscow lens had a good reason: In 1990, I saw a patient with this lens 1 ½ years past operation. Although this lens sitting behind the iris was in contact with the crystalline lens, the latter was completely clear. In May 1991, 1 went to Moscow to see more patients and was assured by Professor Fyodorov and his staff that since starting in 1985, over 725 lenses had been implanted and that cataract was not a complication. In consequence of my visit, early in June 1991, I implanted three lenses myself in Hannover in the presence and under the guidance of Professor Zuev, director of myopia services in Professor Fyodorov's institute in Moscow. The technique was not difficult and the results were excellent (follow up now almost 1 year).
* My present opinion is as follows: I consider the Russian lens an interesting alternative to the anterior-chamber-based hypernegative lenses. It is as yet uncertain which of the three types (anglesupported, iris-fixed, posterior-chamber) is superior and will then become the lens of choice.