[Excimer laser-assisted penetrating keratoplasty : On 1 July 2019 excimer laser penetrating keratoplasty celebrates its 30th anniversary. Video article].

BACKGROUND AND
OBJECTIVE: Since 1986 Naumann and Lang have developed and optimized the technique of nonmechanical corneal trephination using a 193-nm excimer laser along metal masks for penetrating keratoplasty (PKP). The aim of this paper is to demonstrate the technique of excimer laser-assisted keratoplasty.
METHODS: After beginning with elliptical transplants a major improvement resulted in the introduction of eight "orientation cogs/notches" at the edges of round metal masks for reduction of "horizontal torsion". For noncontact donor trephination from the epithelial side an artificial anterior chamber is used. The surgical technique is demonstrated in detail and in almost full length in a video of the operation, which is available online.
RESULTS: Prospective clinical studies have shown that the technique of noncontact excimer laser PKP improves donor and recipient misalignment, reduces "vertical tilt" and "horizontal torsion" of the graft in the recipient bed. This results in significantly less keratometric astigmatism, greater regularity of the topography and better spectacle-corrected visual acuity after removal of the sutures. Besides less perioperative disturbance of the blood-intraocular fluid barrier, excimer laser trephination does not induce enhanced cataract formation and does not impair the graft endothelium. Likewise, the rate of immune reactions is not adversely affected by the excimer laser. Furthermore, trephination of an unstable cornea, such as (nearly) perforated corneal ulcers or after radial keratotomy or LASIK is facilitated.
CONCLUSION: Because of the undisputed clinical advantages, especially in eyes with advanced keratoconus, excimer laser trephination with orientation cogs/notches is currently favored in the routine daily practice in Homburg/Saar.