Femtosecond laser technology useful in penetrating keratoplasty

There is increasing interest in using the femtosecond laser to perform penetrating keratoplasty, according to two corneal experts.

Thus far, the preliminary experiences show that the laser provides good cuts, and future alterations of the technique may eliminate the use of sutures. In addition, the very early experience in one study showed the good interface between the donor and recipient tissue.

The initial results of femtosecond laser-assisted penetrating keratoplasty 1 month after the procedure was performed indicated that the anterior and posterior cuts were visible and in good apposition to each other, which was confirmed on optical coherence tomography. The procedure is promising. No substantial modifications of the current surgical technique were required. This experience demonstrated the flexibility, design, and innovative customized incision configurations of the procedure, according to Erich Braun, MD, a fellow, Department of Ophthalmology, University of California, Irvine.

The standard penetrating keratoplasty procedure involves a standard vertical cut, vertical apposition of the tissue edges, and the need for tight sutures. The healing process requires at least 1 year, and the procedure induces substantial astigmatism and wound dehiscence in about 4% of cases. The outcomes are not guaranteed and can be "disastrous," Dr. Braun said.

"The IntraLase penetrating keratoplasty is designed with a posterior vertical cut, a lamellar ring cut, and an anterior vertical cut that creates a so-called 'top hat' configuration," he continued.

With the standard procedure, wound leakage was reported to begin at a pressure of about 38 mm Hg; however, with the femtosecond laser-assisted procedure, the wound remained leak-free up to 240 mm Hg.

As of the time of this presentation, 24 procedures had been performed with the femtosecond laser by six surgeons to treat keratoconus, Fuchs' dystrophy, corneal scarring, and bullous keratopathy, according to Dr. Braun.

"The initial goals of the procedure," he explained, "were to optimize recipient cut dimensions, optimize suturing techniques, and collect the initial postoperative data." The cut dimensions are based on surgeon preference and customized intraoperatively.

Dr. Braun showed a video of the procedure and noted some highlights, one being that when using the laser there is little disruption of the tissue intraoperatively. During the procedure a small amount of Healon is injected to maintain the anterior chamber. He also pointed out that in one of their cases they were able to achieve a dissection through a highly scarred cornea and no additional substantial blunt dissection was required.

"Regarding suturing, the surgeons found that the best technique was to pass a suture through the peripheral posterior lip, and after placement of the initial sutures, various suturing techniques were used successfully," he described.

One month after surgery, the anterior and posterior cuts are visible and were in good apposition to each other. This good apposition was confirmed on optical coherence tomography.

"The early results for laser-assisted penetrating keratoplasty are promising. The technical feasibility in humans has been demonstrated successfully. No substantial modifications of the current surgical technique were required. Finally, the flexibility, design, and innovative customized incision configurations have been demonstrated," Dr. Braun said.

"More patients evaluated over time are needed to assess the wound-healing process, the induced astigmatism, and the strength, and information on those factors should be forthcoming in the future," he concluded.

Another experience

One of the initial experiences with penetrating keratoplasty performed with the Femtec femtosecond laser (20/10 Perfect Vision) indicates that the procedure is safe and accurate, reported Gerd Auffarth, MD, PhD. There were no complications postoperatively and the patients, who had a variety of corneal pathologies, had good visual outcomes.