Surgeons say femtosecond laser improves safety, predictability and quality of LASIK

The femtosecond laser technology may make flap-related issues a thing of the past, according to two surgeons.

ByMichela Cimberle

$ESCRS Winter Refractive Surgery Meeting [logo]$ ROME – LASIK with the IntraLase FS femtosecond laser is safer, more accurate and results in a higher quality of vision and higher patient satisfaction than LASIK with a mechanical microkeratome, according to two surgeons who spoke here.

According to Lucio Buratto, MD, who used the femtosecond laser in a live surgery session at the European Society of Cataract and Refractive Surgeons Winter Refractive Surgery Meeting, “IntraLase is contributing to a new standard of care in refractive surgery and could increase the number of LASIK candidates in future years.”

Jonathan H. Talamo, MD, did his own investigation on a large cohort of patients and said that femtosecond technology is “at least comparable and arguably superior, from the point of view of safety, to mechanical blade-based LASIK,” as it induces fewer complications and has a higher rate of predictability.

Better results

In the live surgery session, Dr. Buratto showed why he thinks LASIK with IntraLase is easier and safer, starting with the preliminary step of corneal marking. He marked the cornea in the standard way, but he said that marks are not necessary because, after laser cutting, the flap is easily replaced in its original position and centration is no longer a problem. Flap performance is also more relaxed than with mechanical microkeratomes, he said; in case of suction loss, the surgeon can stop, wait for the gas to dissipate and for the tissue to go back into its original position, and then repeat the cut after a few minutes.

“Surgery takes slightly longer, but this is compensated by a lesser amount of stress because you feel more protected from intraoperative and postoperative complications. In 1 year, I have had just one case of slightly decentered flap, no partial or irregular flaps, no buttonholes. There was also less DLK [diffuse lamellar keratitis], no epithelial ingrowth, and epithelial defects occurred in very few cases and only in the periphery of the cut,” Dr. Buratto said.

While traditional microkeratomes create meniscus-shaped flaps, thicker in the periphery and thinner in the center, IntraLase flaps have a consistent thickness, which does not depend on corneal curvature or pachymetry, Dr. Buratto said. The high-frequency three-dimensional ultrasound images taken with the Artemis system show the high quality of IntraLase flaps in terms of smoothness and regularity throughout the entire surface, he said.

“This superior quality of the flaps, which has a counterpart also in the very uniform stromal bed surface, can only result in a better quality of vision with fewer induced aberrations. If flap-related problems were the weak point of LASIK, IntraLase may represent the definitive solution, and we’ll be able to take full advantage of the technique from now on,” Dr. Buratto said.

He also commented on the versatility of the femtosecond system, which allows the surgeon to precisely plan hinge position, flap diameter, thickness and centration. Flaps come out “exactly as you want them” with little deviation from the target, he said.

chart

Fewer complications

In a study carried out in two groups of 1,100 and 1,240 patients operated over a 1-year period, Dr. Talamo compared the complications of LASIK using the Moria LSK-One and M2 mechanical microkeratomes and the IntraLase femtosecond laser. The complications analyzed were the incidence of buttonholes and incomplete flaps, epithelial defects, epithelial ingrowth and DLK. A subgroup analysis of flap thickness was also carried out.

“No buttonhole flaps were seen in either cohorts, while we had two incomplete flaps in the Moria microkeratome group and five in the IntraLase group. In such a large cohort of patients, they were both small numbers, and the difference was not statistically significant,” Dr. Talamo said.

He explained that all five cases in the IntraLase group occurred during his first months of using the new system and should be considered a part of the learning curve.

“The pragmatic difference, however, is that the mechanical flaps could be re-treated only 4 to 6 months later, after the keratome bed had healed, while the IntraLase cases were repeated within 5 days,” he noted.

A statistically significant difference was found in the incidence of epithelial defects, which was 1.8% in the mechanical group and 0.3% in the IntraLase group, Dr. Talamo said. This lower incidence of epithelial defects has been reported by several other IntraLase users, he said.

No significant difference was found in the incidence of epithelial ingrowth in Dr. Talamo’s series (two eyes in the mechanical group vs. no eyes in the IntraLase group). However, he said that other surgeons have reported a significant reduction of ingrowth after all-laser LASIK.

DLK after IntraLase has caused some controversy. Some surgeons have suggested that the use of infrared laser energy may increase the incidence of this complication.

“As a matter of fact, in my experience this is not the case. Although the difference was not statistically significant, I’ve actually found a higher rate of DLK in the mechanical LASIK group (2.2%) than in the femtosecond group (1.8%),” Dr. Talamo said.

Predictable flap thickness

Subgroup analysis of three cohorts of about 100 eyes treated with Moria M2, Moria LSK-One and IntraLase revealed two important points, Dr. Talamo said. The standard deviation of flap thickness was approximately twice as large in the mechanical microkeratome groups, and the range of difference was greater. For both of these parameters, the differences between the mechanical groups and the IntraLase group were statistically significant.

“When we did a probability analysis to try and ascertain how often we might get a very thin (70 µm or less) or a very thick (170 µm or greater) flap, there was a tenfold (very thin) and 1,000-fold (very thick) difference between the mechanical groups and the all-laser group. We should remember that very thin flaps are at risk of buttonholes or tears, and very thick flaps may go too deep into the stroma and generate keratectasia. A technique that keeps us away from these two extremes adds quite a lot of safety to the procedure,” Dr. Talamo said.

chart

Disadvantages

Dr. Talamo said that a limitation of this technique is the longer surgical time, but he also said that this is “much less of an issue now than it was during the first few months.” He added that he thinks this is a small price to pay for the safety and predictability offered by the laser device.

The higher costs of the all-laser procedures should be taken into consideration, he said. Another drawback is the occurrence of transient light sensitivity syndrome in some patients between 3 and 6 weeks after surgery.

For Your Information:

Lucio Buratto, MD, can be reached at Centro Ambrosiano di Microchirurgia Oculare, Piazza Repubblica 21, 20124 Milano, Italy; +39-02-6361191; e-mail: office@buratto.com. Dr. Buratto has no financial interest in IntraLase.

Jonathan H. Talamo, MD, can be reached at Cornea Consultants, 100 Charles River Plaza, Boston, MA 02114 U.S.A.; +1-617-523-2010; e-mail: jtalamo@lecb.com. Ocular Surgery News was unable to confirm whether Dr. Talamo has a direct financial interest in the products mentioned in this article or if he is a paid consultant for any companies mentioned.

IntraLase Corp. can be reached at 3 Morgan, Irvine, CA 92618 U.S.A.; +1-949-859-5230; fax: +1-949-461-3323; Web site: www.intralase.com.

Michela Cimberle is an OSN Correspondent based in Asolo, Italy.