American Academy of Ophthalmology Web Site: www.aao.org
A Look at LASIK Past, Present and Future
On June 20, 1989, a United States patent was granted to Gholam A. Peyman, MD, for a method of modifying the corneal curvature of the eye with a surgical procedure in which a flap was cut in the cornea, the flap pulled back to expose the corneal bed, the exposed surface ablated and the flap replaced. And so it was, with little more than a twinkle in a proverbial eye, that laser-assisted in situ keratomileusis was born 20 years ago.
Dr. Peyman and his patent were followed—and preceded—by other pioneers and landmarks in refractive surgery:
• Ioannis G. Pallikaris, MD, performed the first LASIK one year after Dr. Peyman secured the patent.
• To do that Dr. Pallikaris used a version of the first microkeratome designed 40 years previously by José Barraquer.
• And before LASIK was patented, Marguerite B. McDonald, MD, had already performed the world’s first laser procedure on a live human eye—photorefractive keratectomy (PRK) on a myopic patient—in 1988, one year after Theo Seiler, MD, PhD, had performed the first excimer procedure on a human cadaver eye.
• In 1983, before procedures on humans, Stephen L. Trokel, MD, and photochemist Rangaswamy Srinivasan, PhD, oversaw a series of experiments using ablative photodecomposition to remove corneal tissue on freshly enucleated cow eyes.
A child star. LASIK was not formally approved by the FDA until 1999, but it didn’t take long to become the favorite offspring of refractive surgery, mainly because of its popularity with patients. It produced immediate vision correction with fewer side effects than its predecessors. Today, it is the world’s most popular elective procedure—more than 28 million LASIK procedures have been performed worldwide.
“Nobody dreamed LASIK would have the impact on the world that it has,” said Dr. McDonald, who is clinical professor of ophthalmology at New York University and a cornea/refractive surgeon in private practice on Long Island. Dr. McDonald performs both surface ablation and IntraLase LASIK today and notes that surgery preferences differ from country to country. “In the United States, it’s around 70 to 80 percent LASIK to 20 to 30 percent PRK,” she said, but in Italy, for example, those numbers are reversed.
“Every region has a slightly different preference,” she said, speculating that expense, availability and doctor-patient relationships could factor into the equation.
Upstart elbows out PRK. The success of LASIK today doesn’t particularly reveal the incremental progress of its history. “Making precise flaps was a challenge until automated microkeratomes came along to generate more reliable flaps,” said Dr. Pallikaris, who is now director of the Institute of Vision and Optics at the University of Crete. Given today’s available technology to create very thin flaps, Dan Z. Reinstein, MD, who practices refractive surgery at the London Vision Clinic in London, U.K., now sees few reasons to do PRK unless a surgeon only performs a small volume of corneal refractive cases or there’s an indication for using PRK.
“Complications of LASIK are very specialized problems that require expert management to ensure a good outcome,” he said.
“But PRK involves a far more complex healing response with inflammatory mediators, stromal remodeling with or without haze or new stromal deposition, not to mention the slow visual recovery and the fact that patients will intuitively always prefer the LASIK experience.” Unless there is a specific indication for PRK, such as “someone with anterior basement membrane dystrophy or an anterior corneal scar that may be cleared while correcting the refractive error, I don’t believe there is a need now to do PRK.”
And it’s hard to argue with patient satisfaction: A March 2008 meta-analysis of 3,000 peer-reviewed articles published over 10 years performed by the American Society of Cataract and Refractive Surgery found a 95.4 percent patient satisfaction rate among LASIK patients worldwide.1
LASIK Grows Up
The excimer laser and microkeratome certainly advanced the standing of refractive surgery and allowed LASIK to blossom. But two other developments—the femtosecond laser and wavefront technology—have become the gold standard for a contemporary LASIK procedure, said Ronald R. Krueger, MD. He made the first physical description of the effects of excimer laser on corneal tissue in the early 1980s and then in the early ’90s got involved with picosecond lasers for intrastromal ablation, the precursor to a flap made with femtosecond lasers. The FDA approved IntraLase for laser-assisted creation of a corneal flap in 2001 and approved wavefront-guided LASIK for custom correction in 2002.
Femtosecond edging out the microkeratome? “Femtosecond lasers allowed us to come up with a very predictable, reproducible flap that creates fewer complications and, overall, just a little bit better quality vision,” said Dr. Krueger, who is medical director of refractive surgery at the Cleveland Clinic’s Cole Eye Institute.
Dr. McDonald agrees that femtosecond lasers are certainly a cut above the alternative. “It’s not malpractice to use a mechanical microkeratome at this point in time,” she said, “but every month more are done with the IntraLase, and I do believe mechanical microkeratomes will go away in the next two or three years.”
Dr. Reinstein, who has done extensive research in the prevention of corneal ectasia, also credits the femtosecond laser with LASIK’s ability to maintain an edge over PRK. “It’s now possible to create flaps so thin that there is essentially little difference mechanically whether a flap is made or not,” he said. “I’m talking about 80-µm flaps—that’s only 30 µm of anterior stroma in the flap. Given the commonly recommended limit for PRK ablations of a final corneal thickness no less than 350 µm, and the minimum residual stromal bed thickness for LASIK of no less than 250 µm, the difference of 100 µm is larger than the thinnest flaps we are creating. Of course, you need to be able to handle an 80-µm flap without causing microfolds or cracks in Bowman’s or anything else that would compromise visual quality.”
The arrival of wavefront. Following its inauguration with PRK in 1999, wavefront gave LASIK surgeons a level of refinement that they didn’t have previously, said Dr. Krueger. It allowed surgeons to ablate a sophisticated aspheric and asymmetric profile based on measurements from an aberrometer. Combined with computerized topography, wavefront systems provide a much greater assurance of correction with higher-order or induced aberrations.
“Previously, we were afraid that if a patient had big pupils and a high myopic correction, he would have a greater likelihood of getting halos, starbursts or glare, and if so, would be miserable without options for correction,” said Dr. Krueger. With wavefront, however, the surgeon could either choose a customized re-treatment to correct the aberrations that were inadvertently induced, or could perform a primary customized treatment from the beginning, which is the standard today.
Other optimizations. As an alternative to wavefront customization, companies like Wavelight and Zeiss have pioneered optimized treatments, said Dr. Krueger. These are based on the concept that there’s an aspheric profile to laser ablation that maintains the prolate corneal shape and takes into consideration most of the spherical aberration that is induced from a laser vision correction procedure. “It compensates for the induced asphericity right off the bat,” said Dr. Krueger, “so in many cases you don’t have to use wavefront and you can still obtain that excellent visual acuity.”
America falling behind? Dr. Reinstein sympathizes with his U.S. colleagues who he says are somewhat hampered by the FDA regulatory process, making customization limited to wavefront. “I use the CRS-MASTER ablation profile design workstation, with Zeiss software that controls the MEL80 excimer laser, allowing me to control the wavefront measurement derived from the patient. U.S. surgeons only have access to a point-and-shoot system. I can modulate the wavefront to customize it further and make it far more effective than what is possible with U.S. technology,” he said, adding that this technology would be difficult to pass through the FDA. “FDA trials tend to be only for the approval of one thing at a time, with a process lasting three to five years at a $5 million to $10 million expense to a company.”
Dr. Reinstein said that there are extremely useful excimer repair tools that would never justify this expenditure because of their relatively infrequent use. “The paradox is painful,” he said. “The U.S. produces the most advanced and regimented training and accreditation for refractive surgery in the world, but sadly, on the technology front, it appears that things will perpetually remain behind.”
LASIK Here and Now
The suggestion that the FDA’s caution is holding back refractive technology in the United States is further complicated by news reports that LASIK patients are increasingly unhappy with their results. That was the fallout, at least, from hearings held last year by the FDA. (The Academy has created a helpful brochure that surgeons can offer to patients inquiring about LASIK.2)
“Much of the outcry with regard to the hearings was related to cases that happened years ago,” said Dr. Krueger, explaining that deep cuts from microkeratomes, lack of customized treatment, and little understanding of ectasia or induced aberrations accounted for many of these problems.
Put the complaints in context. Over the last few years, LASIK surgeons have gained greater understanding of other complications, as well, said Dr. McDonald. “Some patients have brilliant results—they see 20/20 without glasses; however, they may have photophobia or be unhappy due to dry eye disease,” she said. “There’s widespread appreciation for that, but with smaller, thinner flaps, there’s less dry eye. The femtosecond technology allows us to customize our flaps such that we’re now cutting very few corneal nerves. Each iteration of the solid-state laser is faster, so that the patient doesn’t have to hold still for as long, and the chance of breaking suction goes down. In addition, there are all sorts of fail-safes built into the femtosecond lasers.”
Manage your response to trouble. Anne M. Menke, RN, PhD, is risk manager for the Ophthalmic Mutual Insurance Company in San Francisco, and she recently reviewed all LASIK claims ever filed with OMIC. She agrees that a big payout of claims around 2006 and 2007 is linked to a peak in complaints from previous years, complaints that took a while to wind their way through the system. In actuality, the incidence of claims today keeps going down, she said. Still most surgeons agree that you can’t ignore the nearly five percent of LASIK patients who aren’t happy, often due to one of three concerns:
1. ECTASIA ANGST. Understanding about biomechanical weakening of the cornea continues to evolve. Early on, the risk related to LASIK wasn’t well known, largely because its predecessor, PRK, didn’t seem to produce this problem. Ectasia cases started showing up when LASIK became more commonly performed, and these prompted some large settlements, said Dr. Menke “If you end up with a condition that requires a corneal transplant,” she said, “it’s going to take more money to settle than if the main problem is ghosting of images or dry eye.”
Today, refractive surgeons are using a variety of sophisticated diagnostic tools to spot potential risks. One is the Ocular Response Analyzer, which measures pressure with a puff of air, providing biomechanical information that helps surgeons judge the risk for ectasia.
Ectasia can best be managed by screening out patients, preoperatively, said Dr. Krueger. “The ones who become a problem are the ones you didn’t pick up on when performing topography. Subtle abnormality in the corneal shape can be the earliest indicator. These irregular topographic maps are the kind that end up in lawsuits.”
Dr. Reinstein said that he “tortures” his patients with preoperative (and postoperative) testing. “If you happen to be the one in 700 people who needed that information, we have it,” he said, referring to patients who are most likely to develop ectasia. “As refractive surgeons, we have to have the ‘commercial pilot’ attitude that we want no disasters, zero crashes. Is the information really useful? Not most of the time, but sometimes it is.”
As for addressing progression of ectasia, instrastromal corneal ring segments (Intacs) sometimes can be inserted into a thinned cornea to flatten the central cornea. But they’re not the “be-all and end-all,” said Dr. McDonald, who’s involved with an FDA clinical trial for corneal crosslinking, which appears to stop biomechanical weakening by inhibiting the bulging of steep, irregular corneas and can possibly halt keratoconus.
“Starting in Germany, it’s been the standard of care for 10 years,” said Dr. McDonald. “Our study is not over, but so far, it appears as though the results will echo the results of non-U.S. investigators.” Investigators outside the United States are investigating corneal crosslinking as a preventive procedure in keratoconus suspect cases; the results of those trials are pending. Ophthalmologists who care for patients with ectasia can participate in an online registry by entering data on their patients at www.ectasiaregistry.com.
2. FLAP FLOPS. Fortunately, early concerns about flaps and postprocedure trauma have not materialized into big problems. In fact, said Dr. Reinstein, countless U.S. troops in Iraq and Afghanistan have had LASIK. “As it turns out,” he said, referring to the potential protection against blunt trauma, “Netto and colleagues demonstrated that the femtosecond laser injects more energy into the cornea, producing more interface inflammation and keratocyte activation, and hence a more robust interface adhesion, than do mechanical cold-blade microkeratomes.”3
Although mechanical microkeratomes pose some intraoperative risk, femtosecond laser flap dissections can also go awry, said Dr. Krueger. “It’s not rocket science, but if you’re not doing it right, the dissection can result in a flap tear.”
Surprised by the numbers of flap-related claims, Dr. Menke offers advice for postsurgical management. “You should consider refunding the patient’s money immediately if the case needs to be aborted,” she said. “This is not an admission of liability, and since the patient has not yet had the opportunity to make a demand for a refund in writing, you do not have to report it to the National Practitioner Data Bank. It just makes good business sense. Be honest, communicate regularly and, if the patient has been comanaged, arrange to take over the postoperative care unless the patient lives far away and doesn’t want to travel to see you.”
3. SUSPICIOUS SETTINGS. Another worrisome trend, said Dr. Menke, are wrong settings. This error is often due to changes in the surgical schedule that are not communicated to the staff member who inputs the settings. Juries feel that this is something that should never happen, she added. “As with all procedures, the entire surgical team should conduct a time-out and include the laser settings in the preoperative verification process.”
To correct many complications, however, the hands of American LASIK surgeons are largely tied due to the unavailability of topography-guided ablations, said Dr. Reinstein. “The FDA just approved the Nidek topography-guided ablations, but they only approved it for very minor asymmetries on normal corneas that haven’t had previous surgery.”
Physician, market thy practice honestly. The days of promising lifetime LASIK guarantees and “20/20 vision or your money back” are largely over. Just to be clear, the Academy, ASCRS and the International Society of Refractive Surgery of the American Academy of Ophthalmology issued new strict advertising guidelines for refractive surgeons in 2008. (To see the guidelines, go to www.aao.org and enter LASIK guidelines in the search field.) If the advertising of a refractive practice doesn’t match its informed consent and surgical care is treated like a commodity, surgeons shouldn’t be surprised if patients demand their money back, said Dr. Menke. And in this economic recession, patients are more likely to do so, she added.
LASIK surgeons need to build in adequate preop time, not just for clinical reasons, but also for assessing expectations. A good team that communicates well is also key, said Dr. Menke. This can be a challenge, though, if patients are comanaged. Someone else’s staff is less likely to tell you how the patient is reacting or that a particular patient wouldn’t stop complaining from the minute she walked through the door.
“But if your own team is evaluating expectations, you get more feedback, and your staff may pick up on things a patient might not reveal directly to you. That’s because patients feel freer to be themselves in front of staff,” she said.
OMIC strongly suggests that informed consent not be handed over to comanagers. And Dr. Menke said that while refractive surgeons generally do a good job communicating risks, they may not confirm with the patient what’s being heard or evaluate the patient’s ability to handle setbacks. “If the patient says, ‘I’ll be devastated,’ you might want to respond, ‘Perhaps you should think again.’”
Dr. Menke also thinks surgeons should choose their words carefully. “Don’t use the word ‘enhancement,’” she advised, “since you appear to be promising a better result. Call it repeat LASIK or re-treatment. You’ve got to get across the point that this is surgery and all surgery carries risks.”
Cases Down Now, Good Years Ahead
A symptom of the current recession, Dr. Krueger said, is that potential LASIK patients are staying away. “Since the Consumer Confidence Index is closely linked to LASIK volumes, the recent economic crisis has led to a steep decline is LASIK volumes in many practices across the U.S. Although the number of cases performed at the Cleveland Clinic during 2008 was slightly higher than 2007, early 2009 numbers have begun to reflect this national trend. We anticipate that as the economy begins to recover with the aid of economic stimulus packages, so will the attention and activity with LASIK.”
Still evolving, LASIK continues to offer exciting new options for patients. LASIK to treat presbyopia is on the horizon, for example. With presbyLASIK, the cornea becomes a bifocal aspheric surface that allows people over 40 to see at distance and near, said Dr. McDonald. “Some people will opt for that instead of monovision.” Also coming for presbyopia correction are intracorneal inlays that can be added many years following LASIK, she said. Patients will be able to choose between having repeat treatment with presbyLASIK to provide some reading power or having the nondominant eye implanted with an inlay such as the Acufocus presbyopic inlay.
Dr. Reinstein also has developed a technique for treating presbyopia with an excimer laser, which he describes as a super-safe, LASIK-based alternative to multifocal IOLs that does not reduce contrast or produce night vision disturbances.4
Will surgeons ever see the day when LASIK gets upstaged by a younger sibling? Zeiss offers its Femtosecond Lenticule EXtraction as one possibility, said Dr. Krueger. “They’re saying they can be so precise with their femtosecond laser that they can do the flap and the laser ablation all in one step by delineating the lenticule. And they believe the quality of that cut will be as good as the excimer laser’s. Of course they have to prove it.”
But it’s premature to write LASIK’s obituary. “LASIK is going to be around for a good long time,” said Dr. McDonald.