Advances in microkeratome and femtosecond laser technology are making LASIK safer and more predictable than ever.
And while femtosecond lasers continue to gain popularity, offering patients an all-laser LASIK experience, new premium microkeratomes are making surgeons' decision about whether to switch from using a highly effective microkeratome to a much more costly femtosecond laser a difficult one.
In the March 1, 2009 issue of Ocular Surgery News (Europe/Asia-Pacific Edition), several European and American LASIK surgeons weigh in with their opinions about both instruments.
Choice of femtosecond laser or microkeratome depends on the LASIK patient
Some LASIK surgeons, recognizing the advantages of both devices, opt to choose a femtosecond laser or a microkeratome on a case-by-case basis, depending on the needs of each patient.
Lucio Buratto, MD, in private practice in Milan, Italy, was one of the pioneers of LASIK in Europe. In addition to developing innovative LASIK surgical techniques, Dr. Buratto helped develop the Hansatome microkeratome (Bausch & Lomb) and was the first European LASIK surgeon to use the IntraLase femtosecond laser (Abbott Medical Optics).
Dr. Burrato uses both microkeratomes and femtosecond lasers in his refractive surgery practice. He believes both types of instruments produce excellent results in expert hands, noting that each has specific advantages and drawbacks. For example, some microkeratomes may be extremely accurate and patient-friendly for most cases, but they may not perform as well for small, deep-set eyes. For these cases, a femtosecond laser or a different microkeratome may have a distinct advantage.
“Generally speaking, for the average, uncomplicated cases, I still prefer microkeratomes," says Dr. Burrato. "They are very good, perfectly safe and reliable instruments."
"The femtosecond laser is heavier on the eye and requires a slightly longer suction time, as well as some waiting time for bubble dissipation, which may cause some discomfort and anxiety in the patient,” he adds.
The IntraLase femtosecond laser is Dr. Buratto’s first choice for small eyes, for eyes with large pupils and when preoperative aberrations need to be treated during LASIK.
Femtosecond laser preferred
Michael C. Knorz, MD, medical director of the FreeVis LASIK Center and a professor at Medical Faculty Mannheim of the University of Heidelberg, Germany, has switched from using a microkeratome to using an IntraLase femtosecond laser for 100 percent of his LASIK cases.
According to Dr. Knorz, when he compared the surgical results of his patients who had flaps created with a microkeratome to those who had femtosecond laser flaps, visual outcomes were slightly better in the IntraLase laser group. The laser group also had fewer flap complications, and the IntraLase flaps healed better than the microkeratome flaps, he says.
Dr. Knorz also conducted studies on rabbit eyes to compare the adhesion strength of microkeratome flaps to that of flaps created with the latest-generation IntraLase, the iFS. At 2.5 months after surgery, the laser flaps had twice the adhesion strength of the microkeratome flaps, indicating better healing.
Femtosecond laser flaps also may have additional advantages over microkeratome flaps after LASIK, according to Dr. Knorz. “The IntraLase femtosecond laser can produce thin, planar flaps that, compared with the meniscus-shaped flaps of microkeratomes, minimize corneal weakening and induction of spherical aberration,” he says.
Jérôme C. Vryghem, MD, who works in the Brussels Eye Doctors private practice in Belgium, also is a firm believer in using femtosecond lasers to create LASIK flaps.
Dr. Vryghem typically uses the Ziemer LDV (formerly the Da Vinci, Ziemer Group) femtosecond laser. He has conducted studies to determine the optimum flap thickness for LASIK and found that the Ziemer LDV laser is capable of creating thinner, more predictable flaps than many microkeratomes.
In a study of over 1,500 eyes, Dr. Vryghem found he could create flaps that had a mean thickness of approximately 100 microns (little more than the thickness of the corneal epithelium) with the Ziemer LDV laser, achieving successful outcomes with no clinically relevant complications.
Based on these results, Dr. Vryghem says he now performs all-laser LASIK on nearly 100 percent of his patients, using a microkeratome only when patients are not ready to pay the extra costs involved when a femtosecond laser is used.
Advanced microkeratomes popular among many surgeons
But don't write off microkeratomes too quickly. Other surgeons point to new microkeratome technology that can produce similar outcomes as those produced with the latest-generation femtosecond lasers, and at a fraction of the costs.
Richard A. Norden, MD, of Ridgewood, New Jersey, says laser-style thin flaps with a planar architecture can be achieved with the new Moria One Use-Plus SBK microkeratome.
According to Dr. Norden, the Moria SBK microkeratome can produce 100-micron flaps like those created with a femtosecond laser and can create flaps quicker than those produced with a laser. Also, there may be less risk of inflammation and discomfort after surgery when the microkeratome is used, he says.
Dr. Norden also says flap thickness is extremely predictable with the Moria SBK microkeratome, and, unlike most microkeratomes, it produces a laser-style planar flap which may heal better than traditional meniscus-shaped flaps created by other microkeratomes. (Planar flaps have an equal thickness throughout and a blunt edge, whereas meniscus-shaped flaps vary in thickness from center to periphery and have a knife-edge.)
Microkeratomes and femtosecond lasers will likely coexist
Most surgeons agree that advances in microkeratome and femtosecond laser technology have made both instruments very viable for the important first step of creating consistent, predictable flaps in LASIK surgery. In the hands of experienced LASIK surgeons, both devices are safe, causing few LASIK risks.
“I think that wherever surgeons have a free choice, femtosecond LASIK will become the standard of LASIK surgery,” says Jorge L. Alió, MD, PhD, of the Vissum Eye Institute in Alicante, Spain. “However, if price is an issue—and indeed it is—we can still rely on microkeratome LASIK as a very safe and effective alternative.”
SOURCE: "Femtosecond lasers continue to gain ground as improvements are made to microkeratomes" Ocular Surgery News - Europe/Asia-Pacific Edition. March 1, 2009.
