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Up Front | Jun 2002

LASEK’s Impact on the Microkeratome

Will a new process replace the old?

What is the future of the microkeratome? Will LASEK replace LASIK, rendering the microkeratome obsolete? We asked a variety of top surgeons to share their thoughts on this controversial topic. Several were pro-LASEK; others pointed out its disadvantages. A few felt that the microkeratome's days were numbered, whereas others were confident that its future is secure. Interestingly, one surgeon mentioned that the term LASEK was outdated, and has been replaced by what he calls Advanced Surface Ablation. And what about the label, “New PRK?”

Louis Probst, MD, Medical Director of the TLC Laser Eye Center in Ontario, Canada, stated that one of the greatest aspects of ophthalmology and refractive surgery is the rapid rate of innovation. “LASEK is the newest form of refractive surgery, and sometimes new procedures are embraced enthusiastically by the refractive community before we have all the relevant information. Although LASEK is an interesting refractive alternative, there are still many unknown factors and potential risks. There are no reports with any long-term follow-up in the peer-reviewed literature on LASEK,” he said.

According to Dr. Probst, a drawback of LASEK is that all accounts of this procedure depict postoperative pain similar in its severity to PRK; LASEK has never been portrayed as approaching the postoperative comfort of LASIK. He noted that these reports of LASEK describe prolonged visual recovery in the typical PRK range of 4 to 5 days. ?The risk of haze after LASEK cannot be predicted at this time, as the follow-up of the studies to date is too short. Because this is still surface ablation, it is unclear to me how the haze risk with LASEK is any different than the risk with PRK.?

“I am still interested in LASEK,” Dr. Probst concluded, “but before I change my practice patterns from LASIK, the most successful ophthalmic procedure to date, I am going to wait until I know the whole story.”

Marguerite McDonald, MD, Clinical Professor of Ophthalmology at Tulane University in New Orleans, Louisiana, believes that LASEK will not completely supplant LASIK. ?LASEK is just another choice for patients who have corneas that are too steep or too thin for LASIK, or that are too risk-averse,? she said. Dr. McDonald feels that LASEK will never eliminate LASIK, because there will always be a large number of patients who will not wait 2 to 4 days for visual recovery, which is a ?best-case scenario? with LASEK. Often, the recovery is 5 to 7 days. ?Modern LASEK techniques may close the ‘healing gap' by 1 or 2 days, but I believe that LASIK will always offer faster visual recovery.?

Lee Shahinian, Jr, MD, a corneal surgeon in private practice in Mountainview, California, states that, despite LASIK's generally excellent results, complications have been reported in approximately 4% of cases,1 and almost all of these problems are related to the microkeratome and stromal flap. ?With the severing of corneal nerve trunks and the cutting of 200 million stromal collagen fibrils, LASIK has profound and lasting effects on the corneal anatomy and physiology,? he says.

Dr. Shahinian says that LASEK is challenging both the safety and efficacy of LASIK. “Eventually, we will abandon the routine use of the microkeratome in refractive surgery,” he maintains. He also states that, today, there is an irrational exuberance for LASIK, coupled with a large vested interest in the procedure on the part of ophthalmologists, laser centers, and equipment companies. “Whenever safety and efficacy issues are downplayed or ignored, there is a risk that, when a change in attitude finally occurs, it may be sudden and wrenching, with significant financial and professional liability implications.”

“LASEK, which is really PRK plus alcohol, will not replace LASIK,” affirms Lee Nordan, MD, Director of the Nordan Eye Laser Center Medical Group in Carlsbad, California. He notes that LASEK has a 4-day healing period with a contact lens, as well as the potential for haze, similar to PRK. “If a method were developed to lift the epithelium as a sheet and then replace it on the corneal surface with a 1-day healing period, then this new form of PRK would become very popular, especially with low myopia and hyperopia.”

Roberto Pinelli, MD, Scientific Director at the Istituto Laser Microchirurgia Oculare in Brescia, Italy, also does not believe that LASEK will replace LASIK. He performs LASIK on 95% of his patients and employs other forms of refractive surgery on the remaining 5%. Dr. Pinelli feels that, in the future, the superficial approach to the cornea will definitely be an option. “LASIK is such an excellent procedure that there is no reason to consider the microkeratome potentially obsolete.” He asserts that LASIK is a first-rate procedure for many patients due to its favorable features of rapid visual recovery and absence of pain. “LASEK can be an option for patients with low pachymetry readings, but a good PRK procedure (using alcohol), in my experience, does not induce considerable pain in the early postoperative period.”

Michael Lawless, MD, a refractive surgeon from Sydney, Australia, began performing LASEK in October 2000. Currently, he has 18-month follow-up data on approximately 250 patients. Although he was initially very excited about LASEK, his enthusiasm has waned somewhat, as he is not certain that LASEK in its current form offers any benefit over PRK. Dr. Lawless followed his patients' progress for the first 6 to 12 months after some underwent PRK in one eye and LASEK in the other. He indicated that there was not a significant difference in the degree of pain or the rate of early visual recovery, and he reported that, at 6 months, the LASEK patients had slightly more haze, which was most likely due to either the alcohol or the release of material from the injured epithelial cells.

?I think LASEK will have its place in the refractive surgeon's armamentarium (with initial enthusiasm wearing off quickly),? Dr. Lawless mentions, ?unless the epithelium can be removed mechanically (eg, with ultrasound assistance) without using chemicals, so that the epithelium can be replaced without damage. At this stage, the microkeratome manufacturers can rest easy.?

?First, I am in favor of anything that will work,? said Stephen Slade, MD, National Medical Director of the TLC Laser Center in Houston, Texas. ?We should all put any biases or preconceived prejudices aside in favor of safety and the best possible outcomes. LASEK and PRK give us an option for treating patients with thin corneas, epithelial dystrophies, and other special needs.? Dr. Slade believes that some form of surface ablation will be used in the future: ?We know that the aberrations induced by surface ablation are more predictable than with a flap created via LASIK, so this may play a role in improving results.?

Dr. Slade admits that he is a bit cautious when it comes to LASEK, because surgeons need long-term results in order to endorse a procedure fully. He poses several questions: (1) Will LASEK create late haze problems, as happens in PRK? (2) Will LASEK be as easily re-treated as LASIK, or will it be more like PRK? (3) Will patients accept LASEK as readily as LASIK? and (4) What are its advantages over PRK? “At this year's ASCRS meeting, there will be several presentations comparing LASEK to PRK, and the results are surprising,” he comments.

Dr. Slade is confident that the microkeratome will not disappear: “The [micro]keratome is not standing still, but is evolving just as fast as surface ablation. Witness new technology, including small rings and zero compression heads for the Hansatome to reduce epithelial defects, as well as the new approach of laser microkeratomes such as the IntraLase to make flaps. In addition, LASIK clearly will lead in patient comfort and speed of recovery.”

So, will LASEK replace the microkeratome? “No,” asserts Dr. Slade, “and that's really the wrong question. The right question is, ‘Will LASEK grow the field of refractive surgery?' And I think it will. LASEK is a good option with good results, and, the more options we have for patients, the better.”

Carlos Vergés, MD, PhD, a refractive surgeon from Barcelona, Spain, asserts that the imprecision of the microkeratome is the limiting factor in improving the overall precision of LASIK: “I think we should look for another alternative [to the microkeratome]. The LASIK flap limits the ability to improve the laser as it creates its own variables and problems,” he notes. Dr. Vergés says LASEK could be the procedure of the future, but there is not yet an available system to make it possible for the epithelium to be lifted by selectively sectioning the hemidesmosomes. “It is necessary to improve upon the technique of the epithelial sheet creation. When this objective is attained, we will be able to abandon the current LASIK surgery technique, including the microkeratome,” he says.

According to Daniel Durrie, MD, a refractive surgeon from Overland Park, Kansas, the name LASEK is in the process of changing, because the procedure belongs in the general category of advanced surface ablation. In March 2002, at the first international LASEK Congress in Houston, Texas, organized by Richard Yee, MD, and Ronald Krueger, MD, a group of surgeons interested in the procedure met and discussed the pronunciation problems with the name, LASEK, especially when conversing with European surgeons. Dr. Durrie and his colleagues came up with the global term Advanced Surface Ablation. He feels that this is a better phrase to use, because this procedure is performed on the surface, whereas in LASIK a laser is used below a flap. The main difference in the procedures is where the ablation is performed. The term advanced allows surgeons to let patients know that this is not just PRK, but has the previous 15 years of surface ablation experience behind it.

“To me, ‘New PRK' is not a suitable designation,” states Dr. Durrie. He feels that PRK can be a negative term, because the procedure may be considered outdated, and he points out that LASIK replaced PRK. Dr. Durrie comments, “I don't use the term LASEK in the office anymore. I just talk about surface ablation.” He does not feel that advanced surface ablation will significantly affect the microkeratome market, either in microkeratome sales or blades. “Right now, to me, surface ablation is for a different group of patients. In some cases, I do not want to use a microkeratome, but in others it is the patient's choice to stay away from the blade.”

Dr. Durrie projects that in the future, IntraLase technology may significantly affect the microkeratome market, because it may be able to create a better, safer, more precise flap. “As technology develops,” he states, “it is logical that, rather than using a blade to cut the cornea, we will be using a next-generation device, such as the femtosecond laser. I am not really interested in researching a new blade-related microkeratome. What I am interested in, however, is surface ablation and new ways to cut the cornea without a blade.”

For information on “New PRK,” please refer to Dr. R. Bruce Grene's article titled “Expanding Your Refractive Options,” which appears on page 63 of this issue.
Louis Probst, MD, serves as Medical Director for the TLC Laser Eye Center in Ontario, Canada. Dr. Probst may be reached at (519) 250-2020; lprobst@hotmail.com
Marguerite McDonald, MD, FACS, is Clinical Professor of Ophthalmology at Tulane University. She is Director of the Refractive Surgery Center of the South Eye, Ear, Nose, & Throat Institute of Memorial Medical Center in New Orleans, Louisiana. Dr. McDonald may be reached at (504) 896-1250; margueritemcdmd@aol.com
Lee Shahinian, Jr, MD, is Associate Clinical Professor and former Director of Refractive Surgery at Stanford University in Stanford, California. Dr. Shahinian may be reached at (650) 969-7733; shahinian@nova-vista.com
Lee T. Nordan, MD, is the Director of the Nordan Eye Laser Center Medical Group in Carlsbad, California. Dr. Nordan may be reached at (760) 930-9696; lasertn@aol.com
Roberto Pinelli, MD, is the Scientific Director and Chief Surgeon of Istituto Laser Microchirurgia Oculare in Brescia, Italy. He may be reached at +39 030 2428343; pinelli@ilmo.it
Michael Lawless, MD, is from The Eye Institute in Chatswood, Australia. Dr. Lawless may be reached at +61 2 9424 999; mlawless@theeyeinstitute.com.au
Stephen Slade, MD, FACS, is the National Medical Director for the TLC Laser Center in Houston, Texas. Dr. Slade may be reached at (713) 626-5544; sgs@tlchouston.com
Carlos Vergés, MD, PhD, is Head of the Department of Ophthalmology, USP-Institut Universitari Dexeus, Escoles Pies, in Barcelona, Spain. Dr. Vergés may be reached at +34 932 545422; cverges@cverges.com
Daniel Durrie, MD, is in private practice with the Hunkeler Eye Centers in Overland Park, Kansas, and is Clinical Assistant Professor at the Kansas University Medical Center in Kansas City, Kansas. Dr. Durrie may be reached at (913) 497-3737; ddurrie@novamed.com
1. Sugar A, Rapuano C, Culbertson W, et al: Laser in situ keratomileusis for myopia and astigmatism: Safety and efficacy. Ophthalmology 109:175-187, 2002
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