Deep anterior lamellar keratoplasty yields satisfactory best spectacle-corrected visual acuity

April 1, 2008

Deep anterior lamellar keratoplasty resulted in satisfactory best spectacle-corrected visual acuity levels after 18 months follow-up. The rate of graft clarity was almost 90% and the rate of stromal rejection was low. However, the rate of endothelial cell loss at 18 months postoperatively was high.

Key Points

Mexico City-Deep anterior lamellar keratoplasty resulted in satisfactory best spectacle-corrected visual acuity (BSCVA) levels after 18 months of follow-up. The rate of graft clarity was almost 90%, and the rate of stromal rejection was low. The rate of endothelial cell loss at 18 months postoperatively was high, however, said Ramon Naranjo-Tackman, MD.

"We have been trying to demonstrate that the femtosecond laser [IntraLase, Advanced Medical Optics] makes deep anterior lamellar surgery easier compared with, for example, the bubble technique or the microkeratome-assisted anterior lamellar technique, which are currently being performed," he explained.

Dr. Naranjo-Tackman and co-author I. De Obaldía-Faruggia, MD, conducted a prospective study of patients with keratoconus. In Mexico, Dr. Naranjo-Tackman said, about eight of every 100 patients with astigmatism have a certain degree of keratoconus. "We decided not to use a lamellar graft if the corneas were thinner than 350 μm," he said. Dr. Naranjo-Tackman is affiliated with Cornea and Refractive Surgery, Association to Prevent Blindness in Mexico, Mexico City.

Dr. Naranjo-Tackman reported that at the end of the 18-month follow-up, despite the fact that the researchers avoided a recipient bed that was less than 100 μm, loss of endothelial cells occurred.

"We found that there was relatively great loss of endothelial cells. We measured about a 14% loss of endothelial cells during the first year of follow-up. However, we were able to obtain a mean final corneal thickness of 568 μm. Fortunately, the grafts tended to be clear. The main problem with the technique was the impact on the BSCVA. Patients may have acceptable vision during the day, but the problem we have focused on after 18 months of follow-up is that patients have very poor contrast sensitivity," he commented.

Dr. Naranjo-Tackman and colleagues now are comparing, in a new series of patients , the various techniques for the visual outcomes, i.e., the microkeratome-assisted anterior lamellar technique, the femtosecond laser technique, and the bubble technique.

"There are no great differences among the techniques. Anatomically, perhaps one technique provides a better shape compared with the others; however, the patients are all complaining of poor nighttime vision," he stated.

The major complication that occurred with the femtosecond laser technique resulted in the need for a penetrating keratoplasty in one eye 14 months postoperatively because of severely debilitated nighttime vision.

Dr. Naranjo-Tackman said that he began to perform phototherapeutic keratectomy routinely to obtain a finer corneal surface with fewer irregularities compared with the technique under discussion. "The advantages of performing deep anterior lamellar keratoplasty with the femtosecond laser are that the procedure is faster, can be performed using topical anesthesia, carries fewer risks, is more controllable with the femtosecond laser, and the sutures can be removed sooner. However, we have to improve the interface regardless of the technique being used," he said.