Contribution of Optical Coherence Tomography (OCT) with real‐time OCT of the Femtosecond laser, and per operative OCT of the microscope in deep anterior lamellar keratoplasty (DALK) for keratoconus: a new technique

Abstract

PurposeDeep anterior lamellar keratoplasty (DALK) is a treatment of choice for keratoconus. We evaluate the contribution of a new technique associating femtosecond laser with real‐time OCT, and per‐operative OCT on the microscope, in DALK surgeries for keratoconus.MethodsAfter training on artificial anterior chambers of corneal grafts to evaluate the reproducibility of cuts, pre‐cuts of human anterior corneal lamellae during DALK of keratoconus were realized using the femtosecond laser (Victus, Bausch and Lomb) with real‐time OCT and a curved applanation's surface. The depth was caculated around 60% of the thinnest pachymetry. Surgeries were realized using the per‐operative OCT with the Rescan system of the microscope (Lumera 700, Zeiss).ResultsCurved applanation and visualization with real‐time OCT of the cuts’ depth enabled the realization of reproducible lamellar cuts on 200 µ thick corneas, without modifying the laser‐cornea interface neither using masking agents. Femtosecond laser cuts allowed the big‐bubble formation on 10/10 ex‐vivo corneas. In human surgeries, real‐time OCT visualization allowed controlling non‐penetrating cuts, and the curved applanation limited folds formation on the residual stroma. Each surgical step was controlled by per‐operative OCT, with visibility of tissues’ structure and thickness, and instruments in cross section. The Anwar‐air dissection technique permitted the “big‐bubble” formation in 7/7 case, clearly visible on OCT, with only 1 or 2 injections of air. Residual posterior stroma was resected realizing pre‐descemetic lamellar grafts.ConclusionsThis new technique, femtosecond laser associated with per‐operative OCT, appears to be safe, effective, reproducible and time‐saving in DALK surgeries, facilitating the “big‐bubble” formation. It may be proposed for the management of keratoconus and other indications.