Incomplete femtosecond laser incisions ensure wound stability before corneal grafting

J Cataract Refract Surg. 2008;34(12):2099-2103.

Issue: January 10, 2009

Incomplete femtosecond laser incisions left adequate corneal strength, enhancing patient safety and allowing patients to be moved to another operating facility for penetrating keratoplasty.

“Because femtosecond laser [PK] incisions can separate so easily, we do not recommend making complete incision patterns in the recipient cornea under any circumstances, even if the femtosecond laser procedure is performed at the same facility as the transplantation,” the study authors said.

The retrospective case series included 46 eyes of 46 patients, with a mean age of 50 years. Three incision patterns were used: the top hat (26 cases), mushroom (13 cases) and zigzag (seven cases). Each pattern combined a posterior and anterior side cuts, and a lamellar ring cut.

Leaving 70 µm to 75 µm of the anterior or posterior side cut incomplete ensured wound stability. No incomplete lamellar incisions completely separated before PK was performed. However, some eyes had wound instability with a 300-µm incomplete lamellar cut. To compensate, part of the anterior side cut was left incomplete to use the tensile strength of the intact collagen lamellae.

This study demonstrates that a properly constructed femtosecond laser incision for corneal transplantation can be performed safely in a laser center, with subsequent surgery in an operating room that is remote from the laser center. The interruption must occur across multiple lamellae, not within a lamellar structure, to avoid the possibility of spontaneous dissection of the tissue plane. This understanding allows cornea transplant surgeons to make use of femtosecond lasers installed in laser centers to perform the incision patterns that give better clinical results and in a safe manner.

– Roger F. Steinert, MD
OSN Cornea/External Disease Section Member