Comparison of Planar and Curved Applanation Lens for Femtosecond Laser–Assisted Posterior Lamellar Keratoplasty

Abstract

Abstract: : Purpose: To compare the feasibility of femtosecond laser–assisted cutting of the lamellar corneal disc in posterior lamellar keratoplasty with a planar and curved applanation lens. Methods: The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 20 eye bank globes with a planar applanation lens and 2 eye bank globes with a concave applanation lens. Thickness of the excised corneal discs was measured with a digital micrometer and compared with values calculated from the laser treatment parameters and the preoperative ultrasound pachymetric readings. The cut surfaces were examined by light microscopy and scanning electron microscopy. Results:The femtosecond laser was successful in making posterior lamellar and trephination cuts in cornea. The cut surfaces were of very good quality, with a mild stucco texture. In three globes, the cut lamellar surface showed shallow concentric ridges with the planar applanation lens while the curved applanation lens improved lamellar cut surface quality for incisions deeper than 250 µm. Conclusions: These preliminary studies demonstrate that the femtosecond laser can make non–mechanical cuts for posterior lamellar keratoplasty with relative ease and reliability, with smoother lamellar cuts with the curved applanation lens.

Keywords: cornea: clinical science • cornea: endothelium • laser