Loay Daas, Tim Berger, Berthold Seitz
FS-DALK using a hybrid docking approach effectively combines the advantages of nonapplanating and applanating laser steps. The nonapplanating incomplete vertical trephination ensures a perfectly circular trephination, eliminating the oval or "pear-shaped" distortions commonly associated with applanating systems. This refined approach facilitates a predictable "blunt big-bubble," minimizes the necessity for manual dissection, and significantly reduces the risks of intraoperative perforation and conversion to PKP.
PURPOSE: To describe a novel surgical technique for femtosecond laser-assisted deep anterior lamellar keratoplasty (FS-DALK) using a "hybrid docking" approach for the management of advanced keratoconus to avoid high postoperative astigmatism.
METHODS: A proof-of-concept study included 8 eyes of 7 patients with advanced keratoconus and 1 with pellucid marginal degeneration. All procedures were performed using the Femto LDV Z8 femtosecond laser (Ziemer Ophthalmic Systems AG, Port, Switzerland) by a single surgeon. Donor corneas were trephinated using a standard liquid interface. Recipient preparation used a unique, two-step "hybrid docking" approach: (1) a nonapplanating incomplete vertical trephination (8.5 mm diameter, 70% depth) via a liquid interface to preserve natural corneal geometry and (2) applanating intrastromal tunnel preparation into the pre-Descemet stroma, enabling subsequent blunt cannula insertion for the "blunt big-bubble" technique, followed by a deep horizontal lamellar dissection (8.7 mm diameter, 70% depth). Grafts were secured using a double-running 10-0 nylon cross-stitch suture (Hoffmann technique).
RESULTS: A successful "blunt big-bubble" was achieved in all 8 eyes (100%). Notably, no intraoperative micro- or macroperforations occurred, and no case required conversion to penetrating keratoplasty (PKP).
CONCLUSIONS: FS-DALK using a hybrid docking approach effectively combines the advantages of nonapplanating and applanating laser steps. The nonapplanating incomplete vertical trephination ensures a perfectly circular trephination, eliminating the oval or "pear-shaped" distortions commonly associated with applanating systems. This refined approach facilitates a predictable "blunt big-bubble," minimizes the necessity for manual dissection, and significantly reduces the risks of intraoperative perforation and conversion to PKP.