Does a Better Flap Improve Outcomes?
Learn why this surgeon continues to use a mechanical microkeratome for most of his patients.

When I started performing LASIK, microkeratomes were very difficult to use, and in many ways -- certainly by today's standards -- they were highly unreliable. Today's advanced microkeratomes can't compare to their predecessors. I've tried most that are on the market, as well as those that have gone by the wayside, and comparatively speaking, I've found the AMO Amadeus to be the most reliable and easiest to use, so I use it on most of my LASIK patients.

I also use the IntraLase femtosecond (FS) laser in my laser center, so I've been able to compare outcomes, safety, predictability and economy. In this article, I'll discuss the key differences I've found in my practice.

Visual Outcomes

It's too soon to discuss data from our ongoing study of outcomes of CustomVue (VISX) LASIK with the IntraLase, but an earlier study of 100 patients showed that the optical and visual results were better for the Amadeus patients than for the IntraLase patients. We can't draw too much in the way of conclusions from that, however, because we were treating all ranges of myopia with the Amadeus, whereas we were using the IntraLase only for patients who were over -6.00D.

Also, since those procedures were performed, we've resolved some issues, such as diffuse lamellar keratitis (DLK), that affected the IntraLase outcomes. We've seen significantly fewer and, among those, milder cases of DLK and photophobia with the IntraLase than in the earlier days of its implementation. We haven't completely solved the DLK issue, though, and it's still a concern.

Ultimately, I suspect the kind of keratome used will make little if any difference in refractive outcomes. I believe hinge placement will prove to be the only relevant variable, and to minimize dry eye problems in any patient, that hinge should be placed on the nasal side.

The very successfully marketed Hansatome promoted the advantage of a superior hinge but fell afoul of the unanticipated severity of its secondary severing of both sensory corneal nerves. Thus, the fact that the Amadeus does not easily cut a superior hinge while the IntraLase lets you place a hinge wherever you want it is a moot point. Perhaps not surprisingly, this was the same conclusion that the father of the keratome, José Barraquer, M.D., reached 30 years ago.

Predictability and Safety

In terms of the predictability of the flap cut, I've found that the IntraLase does have a slight edge over the Amadeus. Whether or not that translates into a better optical result, however, remains to be shown.

The IntraLase certainly eliminates the inherent risks of using a steel blade in the LASIK procedure. Whether the risks inherent in the Intralase make the latter a preferable modality is also still on the table for discussion. There's a trade-off with the Intralase between energy levels and spacing of the focal spots in the keratectomy. In practice, this means the smoothest beds require the longest time to complete and/or higher energy levels with its risks of inducing DLK. Thus, much of the advantage of the blade-free Intralase may be lost to a greater incidence of inflammation and prolonged translation time. I'm convinced that the Intralase is superior to most mechanical keratomes I've used in the past. I'm not convinced, however, that it's safer than the latest generation of mechanical keratomes, the Amadeus. We've been using the IntraLase FS laser for about a year and the Amadeus for about twice as long. At least in my quality assessments, they seem equivalent.

Our OR staff review complications on a regular basis. Although very rare, LASIK-related complications -- both intra- and perioperative -- occur with both types of keratectomy. While advances in mechanical microkeratomes and the FS laser have improved safety, to say that a laser has rendered keratectomy risk-free is inaccurate and misleading. Surgeon skill continues to play an important role in the accuracy and safety of both devices.

Patient Comfort and Convenience

Patient comfort during the keratectomy is a major objective in any caring surgical environment. I've been somewhat disappointed to find that FS keratectomy actually has proven more unpleasant for the patient. Part of this may be due to the prolonged translation time (on average, three times the duration of a mechanical keratectomy), but those very few patients who have allowed me to perform one keratectomy on one eye and the other on the contralateral eye have been quite impressed with the greater discomfort of the FS process.

This issue of translation time for the FS keratectomy has not been adequately addressed in public discussion. We recently timed 10 IntraLase procedures and 10 Amadeus procedures and compared the findings. With the IntraLase cutting a 9-mm flap, it took 1 minute and 40 seconds +/- 3 seconds. With the Amadeus keratome, it took 26 seconds +/- 1 second.

Practice Perspective

We have a large refractive surgery practice, and we've been fortunate to be able to evaluate, invest in and implement new technology as it becomes available. At this point, I'm certainly not ready to sell my IntraLase FS laser because we're still very much in the evaluating stage. Should it eventually prove a real benefit to LASIK, however, there's still the very real issue of its cost.

Comparable to an excimer laser in terms of maintenance requirements and acquisition expense, the FS laser will need to provide unambiguously superior performance to justify its utility. At present, I honestly can't say this is the case. From a financial point of view, it's been difficult to rationalize its worth in our practice so far.

We're paying about $10,000 a month in the amortized cost of the IntraLase laser, and the current per-procedure user fee is $150, which we add to the patient's cost. Looking at this from an amortization perspective, we're actually losing money on every LASIK procedure we perform with the IntraLase. But I guess that's the price we pay for implementing new technology. We've come to terms with the concept that the device may never pay for itself.

Meanwhile, we're doing many LASIK cases with it and collecting data so we can determine if we're realizing any added value in terms of safety, accuracy or visual acuity. If we find the only added value is in its appeal to patients who prefer a bladeless procedure, then that becomes a much more amorphous type of value.

Continued Improvement

To be fair, I don't think the FS laser has reached its full potential. I think its future is bright because it will continue to improve, although it does have some hurdles to overcome. For instance, I'd like to see the IntraLase make a flap as quickly as a mechanical microkeratome. Also, the optimum energy levels needed to make the cut reportedly vary from machine to machine. This needs to be addressed. The "killer ap," though, would be the ability to perform the keratectomy without a suction ring.

I'd also like to see some improvements in mechanical microkeratomes, as well. A microkeratome that would enable the surgeon to program in the desired thickness and diameter of the intended flap once the keratome is put on the eye would be very useful and is well within the range of current technology.

One further point of distinction between the FS laser and the mechanical microkeratome is first-day postoperative vision. Generally, patients who undergo LASIK with the Amadeus see more clearly on day one than patients who undergo LASIK with the IntraLase FS keratome. This delayed gratification detracts significantly from the 'wow factor,' which normally acts as a stimulus for referrals. The idea of having a laser instead of a blade is certainly very attractive to the public, but it would be foolish to ignore the importance to the patient of 20/20 vision on the first day. The future of keratectomy technology has not been decided.

Dr. Woodhams is a clinical associate professor of ophthalmology at Emory University in Atlanta, and the founder of the Woodhams Eye Clinic, Laser & Lens Implant Center.