title: Effect of corneal hydration on the quality of the femtosecond laser anterior lamellar cut.
abstract: The goal of this study was to assess the effect of corneal hydration on the quality of the femtosecond laser (FSL) anterior lamellar cut. The Visumax FSL was used to dissect an 8-mm-diameter corneal flap in 22 eye bank corneas showing various levels of hydration. The intended ablation depth was 220 µm in all eyes, which corresponded to the maximal depth available with this laser. After the cut, the achieved ablation depth was measured using optical coherence tomography images, flap separability was assessed by measuring the mean force generated to detach the flap, and stromal bed roughness was assessed by measuring the Haralick contrast level on the 1000× scanning electron microscopy images of the ablated surfaces. The preoperative central corneal thickness ranged from 547 to 1104 µm (mean ± SEM: 833 ± 30 µm). A negative correlation was found between the level of corneal hydration and the ablation depth measured in the mid-peripheral cornea (r =  -0.626, p = 0.003), the ablation being more superficial in more edematous corneas. The Haralick contrast also tended to increase as a function of corneal hydration (r = 0.416, p = 0.061), suggesting that laser ablation in edematous corneas results in rougher stromal surfaces. These results support the hypothesis that the quality of the FSL lamellar cut decreases as the level of corneal hydration increases. Although FSL is still considered in the field as the tool of the future for corneal dissection, a better understanding of the limits of this tool will be needed before it can replace manual or automated stromal dissection techniques in hydrated corneas.
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Montreal, Québec, Canada; Ain Shams University, Cairo, Egypt.
authors.forename: Ossama
authors.initials: O
authors.lastname: Nada
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Montreal, Québec, Canada.
authors.forename: Anca
authors.initials: A
authors.lastname: Marian
authors.affiliation: Biomedical and Chemical Engineering and Groupe de Recherche en Sciences et Technologies Biomédicales, École Polytechnique, Montreal, Québec, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tran-Khanh
authors.affiliation: Biomedical and Chemical Engineering and Groupe de Recherche en Sciences et Technologies Biomédicales, École Polytechnique, Montreal, Québec, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Buschmann
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Montreal, Québec, Canada; Department of Ophthalmology, University of Montreal, Montreal, Québec, Canada; Focus Vision Clinic, Verdun, Québec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Podtetenev
authors.affiliation: Institut National de la Recherche Scientifique - Centre Énergie Matériaux Télécommunications, Varennes, Québec, Canada.
authors.forename: François
authors.initials: F
authors.lastname: Vidal
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Montreal, Québec, Canada; Department of Ophthalmology, University of Montreal, Montreal, Québec, Canada.
authors.forename: Santiago
authors.initials: S
authors.lastname: Costantino
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Montreal, Québec, Canada; Department of Ophthalmology, University of Montreal, Montreal, Québec, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Brunette
mesh_terms: D003315:Cornea / Q000378:metabolism* / Q000601:surgery*; D003319:Corneal Stroma / Q000378:metabolism / Q000601:surgery; D048988:Corneal Surgery, Laser / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects / Q000379:methods*; D013524:Surgical Flaps; D016896:Treatment Outcome