Femtosecond Laser-assisted Endothelial Keratoplasty: A Laboratory Model

PURPOSE:To evaluate the ability of a 40-kHz femtosecond laser in performing posterior stromal ablation for endothelial keratoplasty. METHODS:Human corneoscleral rims were mounted on an artificial anterior chamber. After corneal pachymetry, the femtosecond laser was used to create a donor lenticule by using a variety of diameter ablations, 150 μm from the Descemet membrane. After ablation, the donor lenticule was peeled from the posterior surface and examined under light and scanning electron microscopy. Grading of ease of peeling and removing of the donor lenticule was assessed. RESULTS:The 40-kHz laser was able to produce effective dissection at low power in the posterior stroma. Modification of laser parameter settings was needed to improve the quality of stromal bed ablation. Double pass ablation of the bed significantly improved ease of peeling and removing of the donor lenticule. This was corroborated by smoother ablations on light and scanning electron microscopy. However, multiple pass ablations did not improve vertical rim dissections, which were satisfactory when single passes were used. CONCLUSIONS:Femtosecond laser-assisted endothelial keratoplasty is a viable alternative to microkeratome-assisted endothelial keratoplasty. Customized nomograms are needed for deep stromal ablation.