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Manual vs femtosecond laser-assisted deep anterior lamellar keratoplasty with intraoperative optical coherence tomography-guided big-bubble channel: a multicenter case study with one-year follow-up

Poster Details

First Author: V.Wittwer SWITZERLAND

Co Author(s):    R. Donner   T. Seiler   G. Schmidinger              

Abstract Details


To compare the intraoperative and postoperative outcome of manual to femtosecond laser (FSL)-assisted deep anterior lamellar keratoplasty (DALK) with intraoperative optical coherence tomography (OCT)-guided creation of a big-bubble channel (BBC) to facilitate intrastromal air injection.


Retrospective multicenter case study with two well experienced surgeons, one at a university hospital in Austria and one at a private tertiary care center in Switzerland.


In total, 124 eyes with advanced keratoconus, corneal scars, and stromal dystrophies, were included. 51 eyes (group 1; age 37, ± 14) had manual DALK between 2011 and 2017 and were compared to 73 eyes (group 2; age 42, ± 14) which were treated with FSL BBC DALK (Ziemer Z8 system) between 2015 and 2018. For group 2, FSL-integrated OCT was used for direct visualization and calibration of the lamellar cut and the BBC, which reaches from the side cut towards the middle of the cornea, exactly 50 μm above the endothelium.


In the BBC group (group2), the rate of BB achievement was significantly higher (0.82) and the conversion rate was significantly lower(0.14) compared to the manual group (group 1), 0.5 and 0.53, respectively (2 (2, N = 124) =6.78, p<0.01). However, microperforation, duration of surgery and rebubbling rate did not differ significantly from one to the other group. In the 12-month follow-up, after removal of the sutures BCVA was not significantly different (p=0.67) in group 1 compared to group 2, 0.39 ± 0.23 LogMAR and 0.36 ± 0.27 LogMAR, respectively. Similarly, no significant differences could be proved for Kmin and Kmax either.


This novel OCT-guided FSL DALK technique allows for exactly plannable creation of a BBC, which facilitates safe BB creation. Accordingly, the risk of perforation of Descemet’s membrane drops significantly resulting in a higher success rate of DALK.

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