COVER STORIES | SEP 2005 ISSUE
Transitions in Refractive Surgery
Surgeons discuss their shift from RK, automated lamellar keratoplasty, and keratomileusis to excimer PRK/LASIK.
PERRY S. BINDER, MS, MD
I pushed my first microkeratome across a human eye in September 1977 in Bogotá, Colombia, with Professor José I. Barraquer, MD, and it was so exciting that I returned to the US to write my first 10-year grant to study refractive surgery procedures.1 There was little change in microkeratome technology for keratophakia and keratomileusis until Luis Ruiz, MD, of Bogotá, introduced the modified Steinway microkeratome for automated lamellar keratoplasty (ALK).
My colleagues and I implanted convex and concave hydrogels (and other polymers) under flaps in human eyes using the available microkeratomes,2 and, although the results were surprisingly good, they could have been much better had we had better instrumentation. With the advent of incisional keratotomy surgery, we incised our first corneas with fresh razor blade fragments, the extension of which was estimated on a metal guide in 1980,3 but it was the Prospective Evaluation of Radial Keratotomy (PERK) study that forced us to use ultrasonic pachymetry and diamond blades with accurate gauges.
During past decades, I have lived through variations in collagen shrinkage, including thermokeratoplasty, Los Alamos keratoplasty, the Fyodorov technique of radio thermokeratoplasty, Holmium:YAG technology,4 and now conductive keratoplasty. My first excimer laser in 1986 was a laboratory model that I aimed across a room to strike a rabbit cornea.5 I used the Visx 2020B (Visx, Incorporated, Santa Clara, CA) for my first clinical case in April 1990,6 and soon RK and ALK were replaced.
An explosion in microkeratome technology followed the introduction of LASIK, but very little has changed in how the cornea is mechanically cut, although blade quality and controlled microkeratome translation have improved.7,8 The introduction of femtosecond laser technology has given us the opportunity to further refine the predictability and safety of LASIK flap creation.9 Our diagnostic equipment has improved from hand-digitized keratoscopic pictures and optical pachymetry to high-frequency ultrasound, confocal imaging, Scheimpflug analysis, and enhanced topographers. Wavefront analysis and improved algorithms that combine wavefront analysis with topography promise to enhance our visual and refractive outcomes toward our goal of 20/10 in 2010.
STEVEN J. DELL, MD
My initial experience with refractive surgery began in residency in the early 1990s at Tulane University in New Orleans. At that time, having residents performing refractive surgery was considered somewhat heretical, but Miles Friedlander, MD, Professor of Ophthalmology at Tulane, insisted that the residents have a strong background in this discipline. Together, the residents and faculty set up a program to allow the indigent to receive refractive surgery, essentially at no charge. Delicate instruments were carried back and forth from the private clinic to Charity Hospital and the VA Hospital under the worried eyes of the faculty. Some diamond blades were never the same again.
While we learned all about the intricacies of RK, ALK, keratomileusus, and even epi-keratophakia, I knew that something profound was about to change. PRK trials were underway, and we were amazed by the postoperative results. It seems trivial now, but, at the time, our inability to tell at the slit lamp which eye had been treated was quite surprising.
In the years prior to the FDA's approval of an excimer laser, RK for low-to-moderate myopia constituted the vast majority of my refractive practice. When conservatively applied, RK was a successful procedure for these patients, particularly when slight residual myopia was targeted. Unfortunately, RK was eventually used in many inappropriate cases with poor postoperative results. The technical challenges and relatively poor quality of vision with ALK generally steered me away from this technology, particularly when the excimer laser's approval seemed close.
One of the practices our group acquired in the mid-1990s had treated more than 10,000 RK patients, and I have become more familiar with the long-term consequences of these cases than I would prefer. Treating the residual ametropia of these patients can be very rewarding, and customized wavefront-guided treatments have improved our ability to handle them. The postkeratorefractive IOL calculation puzzle has also been a challenge, and we need to develop better ways to determine the true corneal power in these adulterated corneas.
The early shift from PRK to LASIK demonstrated that patients highly value a rapid visual recovery from surgery. As the pendulum swings back a bit toward surface ablation, we will undoubtedly find an equilibrium that maximizes the benefits of each procedure.
In the past decade, the technological shifts in the precision and accuracy of refractive surgery have allowed it to move from the fringe to mainstream, modern ophthalmic practice. Most graduating residents now have some training in refractive surgery. Although the subspecialty's market penetration has increased dramatically, there is still enormous room for growth as it becomes more widely accepted by patients. As we deliver better results, this trend will continue.
LEE T. NORDAN, MD
The advent of the excimer laser for performing PRK and then LASIK was a landmark in refractive surgery. For me, it was an exciting and enjoyable transition, not only because I had been performing refractive surgery for 12 years prior to the start of the US PRK trials in 1991, but also mainly because I believed that refractive surgery was going to become a major factor in the future of eye care.
In 1978, I met Professor Barraquer during my corneal fellowship at the Jules Stein Eye Institute of UCLA, and, by 1979, I was studying keratomileusis under his tutelage in Bogotá. Most importantly, Professor Barraquer's attitude that eyes with a refractive error had a disease that surgery could correct was a revelation that I quickly embraced. I shared his belief that most members of society strongly desired to function without glasses or contact lenses.
Subsequently, I met Dr. Ruiz, and had the pleasure of naming his trapezoidal keratotomy for the correction of astigmatism. From my exposure to corneal transplantation, I knew early on that the correction of astigmatism would play a vital role in determining the success of any refractive surgery procedure.
Awed by Professor Barraquer's intellectual ability and his practical solutions to correct ametropia (keratomileusis involves creating a corneal flap with a microkeratome, freezing this corneal disc, adjusting the cryolathe's settings, lathing a new shape in the frozen cornea, and suturing the corneal flap back into position, all in 15 minutes), I began my journey into refractive surgery. Along the way, RK would come and go along with epikeratophakia. After performing keratomileusis regularly, transitioning to the Visx S2 laser (Visx, Incorporated) was truly an enjoyable and rather simple experience. My only concern about the excimer laser was that it would create a corneal surface that was slightly less smooth than that created by the lathing tool during keratomileusis. A pristine refractive surface of the cornea depends mainly on the epithelium, not the stromal surface, and this important principle has been reaffirmed by PRK and LASIK.
Excimer laser refractive surgery was a wonderful and enjoyable experience for me along the path of improved refractive surgery. Most importantly, the excimer laser re-emphasized to me that a surgeon's attitude is the most important aspect of refractive surgery, no matter how advanced the technology, and that a true refractive surgeon should be willing to use a combination of all available technology to achieve the best possible results. The road to improved results in refractive surgery continues, and I salute the contributions made by the developers and users of excimer laser technology.
STEPHEN G. SLADE, MD, FACS
Early on, I got involved with many new technologies. I would like to think my participation was always due to my own wise choices, but talented, gracious mentors and luck were more important.
For example, myopic keratomileusis was not the easiest way to start refractive surgery. I learned the technique from the masters, Lee Nordan and Eric Weinberg, in 1983. It was the hardest surgery I ever performed, so it is no wonder it taught me the most.
After myopic keratomileusis, I learned RK, ALK, and PRK. In 1991, through the kind mentorship of Steve Brint, MD, of New Orleans, I began performing LASIK in the US as part of the Summit-sponsored FDA trial. These were the first cases in the US, again organized by Steve Brint.
Since LASIK, I have seen keratophakia, phakic IOLs, refractive lens exchange, conductive keratoplasty, Intacs (Addition Technology, Inc., Des Plaines, IL), LASEK, and epi-LASIK come along and make an impact (or not). I have learned several guiding truths through this experience. Few procedures live completely up to their hype. Many surgeons will push an operation past its limits and hang on to tested options. It is best to have as many valuable options available as possible to match the procedure to the patient. Additionally, knowing when to stop and when to start using a technique is important.
Patients will choose the better operation. Surgeons, as well, will choose better procedures. By waiting, one will always know which procedure to perform. But, many of us want to try something first. It is our nature. That is where it gets hard to decide.
I recommend looking for elegance, a lack of dependence on wound healing, adjustability, and rapid results with minimal discomfort to the patient. What the surgery is from the patient's perspective, ultimately, has the biggest influence on the success of any procedure.
Finally, it is worth remembering that safety is our most important concern with any surgery. And, the best safety device is one's own training.
Perry S. Binder, MS, MD, practices at the Gordon Binder Vision Institute in San Diego. He is a paid consultant for Intralase Corp. but states that he holds no financial interest in any product mentioned herein. Dr. Binder may be reached at (858) 455-6800; garrett23@aol.com.
Steven J. Dell, MD, is Director of Refractive and Corneal Surgery at Texan Eye Care in Austin. He states that he holds no financial interest in any product or company mentioned herein. Dr. Dell may be reached at (512) 327-7000; sdell@austin.rr.com.
Lee T. Nordan, MD, is a technology consultant for Vision Membrane Technologies, Inc., in Carlsbad, California. He states that he holds no financial interest in any product or company mentioned herein. Dr. Nordan may be reached at (760) 930-9696; laserltn@aol.com.
Stephen G. Slade, MD, FACS, is in private practice in Houston. He states that he holds no financial interest in any product or company mentioned herein. Dr. Slade may be reached at (713) 626-5544; sgs@visiontexas.com.
1. Binder PS, Akers PH, Deg JK, Zavala EY. Refractive keratoplasty: microkeratome evaluation. Arch Ophthalmol. 1982;100:802-806.
2. Werblin TP, Peiffer RL, Binder PS, et al. Eight years' experience with Permalens intracorneal lenses in nonhuman primates. Refract Corneal Surg. 1992;8:12-22.
3. Melles GRJ, Binder PS. Effect of radial keratotomy incision direction on wound depth. Refract Corneal Surg. 1990;6:394-403.
4. Koch DD, Kohnen T, Anderson JA, et al. Histologic changes and wound healing response following 10-pulse noncontact Holmium:YAG laser thermal keratoplasty. J Refract Surg. 1996;12:623-634.
5. Gaster RN, Binder PS, Coalwell K, et al. Corneal surface ablation by 193 nm excimer laser and wound healing in rabbits. Invest Ophthalmol Vis Sci. 1989;30:90-98.
6. Heitzman J, Binder PS, Kassar B, Nordan LT. The correction of high myopia with the VISX 2020 excimer laser. Arch Ophthalmol. 1993;111:1627-1634.
7. Binder PS, Moore M, Lambert RW, Seagrist DM. Comparison of two microkeratome systems. J Refract Surg. 1997;13:142-153.
8. Flanagan G, Binder PS. Precision of flap measurements for laser in situ keratomileusis in 4428 eyes. J Refract Surg. 2003;19:113-123.
9. Binder PS. The IntraLase FS laser. Clinical results. J Cataract Refract Surg. 2004;30:26-32.
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