A new idea for a refractive surgical procedure emerges: sometimes as a modification of previous procedures (for example, hexagonal keratotomy), sometimes by serendipity (eg, deep lamellar keratotomy for hyperopia [hyperopic ALK]), sometimes as a technological improvement in a preexisting device (eg, phakic anterior chamber intraocular lenses), and sometimes as a new idea stemming from previous work (eg, epikeratoplasty).
Surgeons, often dubbed pioneers, enthusiastically describe this important advance at meetings, in ophthalmic newspapers, and in quickly prepared, colloquial books. Enamored of the idea, other surgeons learn to do the procedure and report their positive experience often based on informal data from nonconsecutive cases.
If the procedure is linked to new instrumentation, commercial firms promulgate the instruments and courses, usually brief 1- to 2-day seminars, taught by surgeon-consultants, some with recognizable reputations and others aspiring to build same.
The combined momentum of uncritical newspaper reporting, commercial advertising, positive spin by perceived experts, and articles in the literature with positive results creates a wave of popularity that surges forward, washing an increasing number of surgeons and patients with it. Sometimes the popularity is sustained simply because "We have no other procedure for that refractive disorder." However, a quiet undertow also develops as complications appear. Initially, the complications are given little public attention, for fear of lawsuits against the surgeon, to avoid tarnishing the growing reputation of the new procedure, or because of lack of understanding of the complications by practitioners, who sometimes behave like the crowd that extolled the beauty of the emperor's new clothes.
Finally, the procedure quietly disappears, sometimes because publications detail less-than-satisfactory results or a spate of complications, but more commonly because of unsatisfactory personal experience. Seldom do surgeons publish articles that detail their negative experiences and reasons for abandoning the technique.
Many refractive procedures have passed through this pattern. Let's look at three.
Hexagonal Keratotomy for Hyperopia
Probably the most infamous was hexagonal keratotomy, a procedure that proves the adage, "Those ignorant of history are doomed to repeat it." Hexagonal keratotomy was first done by Sato and Akiyama in the early 1950s.(1,2) In rabbits, the authors found a steepening of the central cornea, but observed variable results and the induction of large amounts of astigmatism, concluding it was an undesirable technique. Mendez revived it in Mexico in 1983, using intersecting incisions and a 6-mm diameter zone, and it attracted attention in the United States.
The wound healing problems of the intersecting incisions (which were already well known from the intersecting "T" incisions of Fyodorov and the intersecting trapezoidal incisions of Ruiz) led to the use of nonintersecting incisions by Mendez and Jensen. Because this pattern induced astigmatism, surgeons added transverse incisions outside the hexagon (the T-hex operation), which caused irregular astigmatism in many eyes. Casebeer reported results in 46 eyes,(3) vaguely alluding to the irregular astigmatism as an increase in corneal asphericity, observing that hexagonal keratotomy was in the stage of trial and error refinement and informal testing. In spite of these problems and continued modifications, the Casebeer-Chiron courses on refractive surgery taught hexagonal keratotomy to hundreds of ophthalmologists.
Nordan and Maxwell(4-6) published letters to the editor contending that hexagonal keratotomy should be abandoned because it induced irregular astigmatism and reduced quality of vision. Basuk and colleagues(7) (but none of hex's enthusiastic practitioners) documented complications. Most surgeons have stopped doing hexagonal keratotomy--but only after a few thousand patients had received it, many with poor results.
Myopic Epikeratoplasty
This modification of keratomileusis, which used cryolathed, lyophilized tissue as an onlay graft, was popularized by Kaufman and McDonald with the support of Allergan Medical Optics. It is a good example of a procedure promulgated in numerous courses even though the surgical techniques were changing frequently. One unique feature of the nationwide trial was that most of the 116 investigators each contributed a small number of cases, making the trial a "worst case" study of a learning curve. Early results for myopia(8) and modifications of the technique(9,10) were reported, but the procedure proved unpredictable and unstable because of the bending of the epikeratoplasty lenticule. The procedure fell under the auspices of the FDA; AMO stopped making the lenticules, and most surgeons abandoned it, without publication of the follow-up results and complications.
Automated Lamellar Keratoplasty
Discussing ALK presents a more complex challenge, because many refractive surgeons still use it. Keratomileusis in situ (alias, ALK), in which a plano disc or flap of tissue is removed from the anterior cornea and the refractive cut is made with a microkeratome in the bed of the cornea, was popularized by Ruiz as a method of expanding the range of myopic correction and of simplifying the keratomileusis procedure.(11) Although the technique has been shown to reduce a wide range of myopia, it suffers from two fundamental flaws:
Nevertheless, the technique was imported to the United States and propagated widely in courses by Slade and Casebeer with Chiron Vision sponsorship before publication of results.
ALK has contributed to our knowledge of lamellar refractive surgery and has paved the way for excimer laser in-situ keratomileusis (LASIK), in which the refractive cut is spherocylindrical and the diameter of the refractive ablation is 6.0 mm or more.(14-16) Even though LASIK is more expensive and technologically more complex than ALK, I think its spherocylindrical ablation center, larger diameter, greater surgical simplicity and better predictability will cause it to replace ALK, an opinion that requires the proof of published results. In fact, I wonder whether surgeons should continue to do ALK at all.
ALK spawned surgical aberration, capless ALK, propagated by Hollis(17) after he observed that when a cap was lost, the corneal bed reepithelialized and the eye retained a refractive change. He reasoned that this approach was not completely different from excimer laser photorefractive keratectomy. Capless ALK was short-lived because it caused irregular astigmatism and corneal scarring in some eyes.
More Examples
Other procedures have been done in hundreds or thousands of eyes, before problems were detected:
All of the above procedures have increased our knowledge of refractive surgery but I think the clinical morbidity has been too great, as a result of free market madness and its fundamental flaws:
At the other end of the spectrum is regulatory rigor mortis, where surgeons and patients face inordinate delays by government regulatory bodies in the approval of devices used in refractive procedures. Delays in objective assessment of new procedures are sometimes prolonged by mindless resistance to innovation and change by overly conservative ophthalmic organizations and practitioners. Few would dispute that the US Food and Drug Administration provides needed protection for refractive surgery patients. The problem is the long time and the high cost required for approval of devices, such as the excimer laser for photorefractive keratectomy.
An example from the development of intraocular lenses for cataract surgery illustrates the important role of regulation.(18) When closed loop anterior chamber IOLs were being tested, the FDA had approved a core investigation of 500 eyes for each of the Azar, Surgidev, Leiske, Hessberg, and other styles. Had the number of eyes investigated remained at this level, the complications from these lenses (fibrosis of the loops in the angle, corneal edema, and in some eyes the uveitis-glaucoma-hemorrhage syndrome) would have occurred in a limited number of patients. However, in an attempt to meet the demands of surgeons and patients for the latest IOL technology, the FDA allowed the adjunct use of closed loop IOLs, which required minimal reporting. Free market madness emerged and hundreds of thousands of "adjunct" lenses were implanted that led to another peak in the 50-year epidemic of pseudophakic corneal edema,(18) before the lenses were removed from the market.
In terms of refractive surgery, the FDA faces the challenge of establishing guidance protocols, standards for investigation, and criteria for safe and effective outcomes. For excimer laser photorefractive keratectomy, the three-phase investigational protocol has required approximately 8 years for companies to complete. Developing outcomes criteria has further delayed approval and created the feeling of regulatory rigor mortis among US ophthalmologists.(19)
The FDA could decrease the time and expense of such trials by establishing specific "bare minimum" guidelines that cover the major variables of refraction, visual acuity, and complications. Limited substudies could then be done on the more expensive and complex tasks--especially those that do not have well-accepted outcome standards--such as contrast sensivity testing, glare testing, corneal topography, and endothelial specular microscopy. The current requirements for comprehensive prolonged testing on all patients discourage manufacturers from entering the field with new innovations, increase health care costs, exhaust investigators, erode the consistency of patient follow up, and ultimately slow the release of products in the United States.
How can refractive surgeons and commercial firms most responsibly introduce and evaluate new refractive surgical procedures, encourage innovation and early adaptors, and at the same time prevent complications in large numbers of patients? Consider 10 idealistic proposals:
Many surgeons and companies are developing new refractive surgery techniques in the general spirit of these precepts, although they have not completely escaped the influences of premarket madness and regulatory rigor mortis:
Vigorous investigation and honest disclosure of results coupled with personal restraint and a patient-as-partner philosophy allow us to evaluate new refractive surgery procedures without succumbing to either free market madness or regulatory rigor mortis.
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Copyright 1995, SLACK Incorporated. Revised 26 October 1995.
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