Study: Femtosecond laser, iris-recognition wavefront-guided ablation may optimize LASIK

PARIS — The benefits of performing LASIK with a femtosecond laser flap and a combined iris-recognition wavefront-guided ablation were demonstrated in a retrospective series of 1,200 eyes, half of which were treated with conventional LASIK.

"In this series, we compared the different techniques, and we found there was definitely a benefit in the quality of vision and safety," Michael Assouline, MD, said at the French Society of Ophthalmology meeting.

Quality of vision was greatly improved in the femtosecond laser wavefront-guided ablation group because of a significant amount of astigmatism correction, he said.

"About 70% of the patients had no astigmatism after the procedure, compared with the 30% to 40% with conventional LASIK," he said. "This was the first statistically significant clear-cut benefit in our study."

The difference in accuracy of spherical correction was not significant, while the wavefront-guided method demonstrated superiority in terms of higher-order aberrations.

Another aim of the study was to assess whether the wavefront-guided method produced the same results with or without dilation.

"The answer was yes. In other words, wavefront analysis performed preoperatively without dilation doesn't preclude having all the benefits of the technique," Dr. Assouline said.

The last parameter that was tested was contrast sensitivity, which was statistically significantly better in the wavefront group.

"In our opinion, the increased accuracy in the delivery of the laser ablation profile and increased quality of vision are largely due to the fact that iris recognition allows for compensation of the cyclotorsion of the eye during laser ablation," he noted.

In his opinion, the femtosecond laser dissection of the flap also played a role in improving the results of the treatment.

"We get much fewer complications than with a microkeratome: There was no flap displacement, no decentration and only one buttonhole, due to decalibration of the femtolaser, but the patient was treated 1 month later without problems. We had one case of DLK, which is a very low rate in a series of more than 500 eyes," Dr. Assouline said.

He attributed this low rate of diffuse lamellar keratitis to the fact that, along with the femtosecond laser technology, he also used disposable equipment, which reduced the risk of infection or inflammation related to the sterilization process.