By Howard Larkin
From the invention of LASIK to the present day, European ophthalmologists
have pioneered the world’s premier laser refractive procedure
By late 1990, José Güell MD and his colleagues were already well versed in photorefractive keratectomy (PRK) at their Barcelona clinic. But while refractive outcomes overall were quite good, slow recovery was a problem for many PRK patients, and corneal haze could be severe for larger corrections.
"From time to time the outcomes were not as good as we wanted for high myopes," he recalls.
So when Ioannis Pallikaris MD, PhD, reported rapid recovery and clear corneas in blind human eyes for the hinged corneal flap laser in situ keratomileusis procedure he pioneered in a rabbit model, Dr. Güell was ready to take the plunge. In early 1991 he performed his first LASIK procedures.
"We believe they were the first LASIK procedures on sighted eyes in Europe because we were unaware of any other group who already did it," Dr. Güell says.
He later published two-year follow-up results of some of these early cases. The results exceeded Dr. Güell's expectations.
"For some of us with previous refractive surgery experience, the switch to LASIK was fantastic. There was the 'whoa' factor of immediate visual recovery. It was equally rapid for -2 D or -12 D."
The results were so good that Dr. Güell and others pushed the LASIK envelope hard.
"We thought we could correct any degree of myopia up to -20 D, especially in Europe. It wasn't until later that we realised that LASIK was not the best for correction of high myopia, not only for the risk of ectasia but also because of quality of vision issues. It took five or six years to
realise the limits."
In the mid-1990s Dr. Güell codified these insights in published papers noting that outcomes for corrections beyond -12 D were less predictable. These findings also led to his exploration of combining LASIK with phakic IOLs to achieve higher corrections, and the use of LASIK to correct residual errors after other refractive procedures, or induced astigmatism due to decentred previous ablations.
Nonetheless, LASIK caught on quickly, at least in some southern European countries. From the early to mid-1990s, he together with another few colleagues were frequently invited to lecture and instruct in Germany, France, the UK and other northern countries where LASIK was slower to catch on.
"In those days they were not doing LASIK, but now there is very little difference from north to south. LASIK is the number one laser refractive procedure all over Europe, except for Italy, where they still do a lot of PRK."
A worldwide effort
Other European LASIK pioneers also played a major role in making the procedure a worldwide hit. In Italy there was Lucio Buratto MD, an early innovator who used the excimer laser to ablate stroma under and on the back of free corneal caps at about the same time Prof Pallikaris conducted his animal experiments with hinged flaps. In 1991 Dr. Buratto schooled Stephen Slade MD, and Stephen Brint MD, in stromal ablation procedures at his Milan clinic. Dr. Brint carried the knowledge back to New Orleans, where he performed the first LASIK procedure in the US. Dr. Brint, Dr. Slade and other colleagues then headed up the FDA clinical trials for the Summit excimer laser.
At the same time, Stephen Trokel MD, who originally developed the excimer laser for ophthalmic use with the UK's John Marshall PhD, and Charles Munnerlyn PhD, whose ablation algorithms are still the basis for today’s procedures, began LASIK trials with their VISX laser, which was already in trials for PRK. FDA approval of these lasers for PRK in 1995 and LASIK in 1998 paved the way for even broader acceptance of laser refractive procedures worldwide.
And it didn’t take long for the bread that Dr. Buratto and other early innovators, such as Theo Seiler MD, PhD, of Switzerland and Julian Stevens MD, of the UK, cast upon the international waters to come back to Europe. The first LASIK procedures Thomas Neuhann MD, PhD, did in Munich in 1995 went "astonishingly well, not least due to the fact that I had the foremost teacher, Steve Slade, who was kind enough to come to assist in my first cases."
Evidence overcomes skeptics
Even so, LASIK was a difficult sell in Germany, and remained so for years, Prof Neuhann notes. "Like everything new, it was denounced as 'criminal', 'jeopardising healthy people's eyesight for money – greediness,' etc," he says.
Cultural norms also played a big part, Dr. Neuhann believes.
"If you look at the curves for refractive laser surgery increase in the US and Canada, Europe and Germany, the very slow adoption rate over time in Germany is more than obvious. Why is that? It's wide open to speculation, but certainly the German mentality plays a major role. Germans are by default perfectionists. The typical German will say 'Most important is perfection of vision, without visual aids if possible, but I prefer perfect vision
with glasses to 'good enough' vision as anacceptable compromise for freedom of
glasses.' That is even more so if they pay out of pocket for it. The Mediterranean, Latin American and even North American cultures are very different from that."
Prof Neuhann himself was initially sceptical, but the early experience of his European colleagues changed his mind.
"Having done my PhD thesis on corneal wound healing, I could not really imagine that cutting or lasering across the visual axis would not negatively affect vision. That is why I was not a 'first adopter'. Having seen first cases, however, I became an 'early adopter' since my theoretical concerns did not come true."
In recent years LASIK has gained greater public acceptance in Germany, thanks in large part to the work of Prof Michael Knorz MD, PhD, of the University of Mannheim. He performed the first LASIK in Germany in 1993 after attending a presentation at the 1993 ESCRS conference in Innsbruck by Luis Ruiz MD of Colombia. Dr. Ruiz, a protégé of Jose Barraquer MD, inventor of freeze keratomileusis and the microkeratome among other things, was a major refractive surgery innovator in his own right. He invented the dual-keratome procedure known as ALK and played a major role in developing microkeratome and related technologies that advanced LASIK over time.
"I flew to Bogota and spent a few days with Dr. Ruiz to learn the LASIK
procedure," recalls Prof Knorz, who was experienced with PRK. "We both used
the same laser at this time, the Technolas Keracor 116. LASIK was still very tricky. I used the ACS designed by Ruiz, originally designed to perform ALK. In 1993, the ACS did not have a mechanical stop; it was up to the surgeon to stop in time to leave a small hinge. In some of my early cases, as you can imagine, I had too big a hinge, and in some a free cap.
"From the first time I saw Dr. Ruiz perform LASIK it rather intrigued me as
a perfect way to use an excimer laser. I never liked PRK and all the pain, the slow healing, the 'haze,' which is just another word for scar, and the not-very-happy patients. LASIK was so much better."
Nonetheless in the early days in Germany LASIK remained suspect. Prof Knorz believes he was able to get started mostly because he was in a university setting, making him less of a target than if he were in a private clinic. Prof Neuhann limited the procedure to patients he believed had disabling refractive conditions.
Prof Knorz also initially limited LASIK to high myopes, from -6 D to -25 D – which turned out to be a mistake. "Later on, I published my results in Ophthalmology and concluded that LASIK above -15 D is not feasible. Today, we know that the upper limit is even lower, around -8 to -10 D."
Dr. Güell defines the range another way: "Besides the well known thickness limitation, human beings have a corneal mean curvature between 39 and 46 D. As long as the final K is within these limits, it is OK. If you end up with a lower K than 39 or higher than 46, you have quality of vision problems."
Still, Prof Knorz says his early LASIK patients were happy despite the side effects resulting from their high myopia.Those early patients were adventurous personalities, not comparable to the mainstream patients we have today. He says it was easier to get started in LASIK in a university because he conducted his work in a university setting.
Eventually, the research conducted by Prof Knorz, Prof Neuhann and others broke down resistance. Surgeons from all over Germany and Europe came to Mannheim to study with Prof Knorz.He also went on the road as a trainer, introducing LASIK in India. In Germany, a committee known as the KRC was formed in 1996 to develop standards for LASIK and other refractive procedures, and in 1999 LASIK was approved by the German Ophthalmological Society (DOG).
Technical advances drive acceptance
While some of the earliest pioneers of laser surgery hailed from Britain, including Prof Marshall and Julian Stevens MD, FRCS, who developed PRK with Dr. Trokel, concerns about LASIK slowed its acceptance in the UK, notes Emanuel Rosen FRCS, FRCOphth.
"British society is innately conservative; we wanted to know it was safe and stable before undertaking it. The real pioneers were in Europe, not the UK."
Like others, Dr. Rosen was attracted to LASIK because it seemed to solve many of the problems of PRK. But microkeratome issues, and difficulties with early widebeam lasers such as creation of central islands and problems maintaining a consistent beam profile, gave him pause. The introduction of flying spot lasers with eye tracking helped.
"I was partly waiting for the equipment to improve and partly waiting for the literature."
In 1995, he did the first LASIK procedure in the UK, closely followed by Sheraz Daya, MD.
With more-reliable equipment and better outcomes thanks to the research of the pioneers, in the late 1990s LASIK moved into the mainstream. By the time the first ESCRS member survey was conducted in 1998, 33 percent of respondents said that they did at least one LASIK procedure a month in the previous year. In 1999, that figure shot up to 72 percent. Surgeons also showed a marked preference for LASIK over PRK in 1999, with 83 percent saying they planned to start or increase LASIK compared with 49 percent planning to do more PRK.
As aberrometers and custom-guided ablations became available, European surgeons were again out front. Among them, Prof Seiler's investigations of overcorrecting existing aberrations and correcting aberrations induced by decentred aberrations helped develop guidelines and limits for wavefront guided procedures. Prof Pallikaris and others developed methods for fine-tuning
ablations.
Surgeons including Prof Neuhann have added to the understanding of the importance of centring ablations on the visual axis – and helped develop increasingly sophisticated eye-tracking technology that can follow cyclotorsion and z-axis shifts to maintain the precise aim upon which wavefront-guided ablations rely.
"I see LASIK going to corneal wave front-oriented ablation algorithms as opposed to total wavefront based. I see intraoperative pachymetry, cyclo-tracking and automatic visual axis finding in the near future to become standards of care," he says.
"The LASIK of the future will be all-laser LASIK, which means we will use a femtosecond laser to cut a flap and then an excimer laser to ablate the tissue to perform the refractive correction." - Michael Knorz MD, PhD
Dr. Güell believes that the reliability of LASIK is such that it will remain the dominant laser refractive procedure for some time to come especially on the lower corrections rate in both primary and secondary surgeries. While the number of procedures has plateaued in Europe, he expects growth will resume as a new generation of myopes ages and can afford the procedure. However, better pain and haze management will also benefit surface procedures. Femtosecond approaches beyond flap cutting are also likely to gain, he believes. European surgeons are at the forefront of this research as well, he notes.
Prof Knorz foresees LASIK settling into a niche among other refractive surgery
options.
"The LASIK of the future will be all laser LASIK, which means we will use a
femtosecond laser to cut a flap and then an excimer laser to ablate the tissue to perform the refractive correction. I also think that LASIK will be used for lower myopes and hyperopes only. I envision a range from +3 D to -6 D. In addition, LASIK will be used to fine-tune results of other refractive surgical procedures, such as phakic implants and refractive lens exchange. I believe LASIK is here to stay."
Published with permission of EuroTimes, official magazine of the European Society of Cataract and Refractive Surgeons (ESCRS). See www.eurotimes.org
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