Femtosecond Laser Keratoplasty

Zirm performed the first successful human full-thickness corneal transplantation in the early 1900s. He performed the surgery without finely gauged needles, sutures, or modern-day viscoelastic devices. In the century that followed, numerous innovations brought penetrating keratoplasty (PKP) procedures to a new level of anatomic and optical success that few surgeons could have imagined. Ramon Castroviejo pioneered the most common PKP technique still in use today by creating a circular corneal button with a circular trephine blade. Multilevel stepped corneal incisions for improving donor-host alignment and wound stability were introduced initially by Franceschetti and Doret in the 1950s. Soon thereafter, Barraquer expanded on this concept and developed a method and special instruments to manually create a ‘‘2-level’’–shaped incision, with an inner diameter larger than the outer diameter, to preserve greater areas of endothelium in the surgical management of Fuchs’ dystrophy. The difficulty of this technique prevented widespread adoption. Forty years later, Busin described a ‘‘mushroom’’-shaped manual PKP technique that also had a stepped incision, but with a smaller inner diameter than outer diameter, a potential advantage for PKP in patients with healthy endothelium that could be retained. Nevertheless, the challenge of a manually shaped donor and host prevented most surgeons from adopting the shaped incisions, despite the potential improvements in wound integrity and donor-host alignment. The concept of shaped PKP took a major leap forward with the development of the femtosecond (FS) laser for corneal incisions. This technology was first developed as a commercial device in the late 1990s for creation of the corneal flap in laser in situ keratomileusis. The FS