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Aurelien Hay, Antoine Rousseau, Michele Savoldelli, Virginie Garnier-Thibault, Francine F. Behar-Cohen, Jean-Louis Bourges; Thickness Regularity Of Femtosecond-assisted Endothelial Keratoplasty Buttons Measured By Anterior Segment Oct. Invest. Ophthalmol. Vis. Sci. 2012;53(14):35.
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© ARVO (1962-2015); The Authors (2016-present)
Buttons for endothelial keratoplasty (EK) can be prepared using a femtosecond laser (FS). Besides interface smoothness, thickness irregularities may explain disappointing visual results obtained with the FS-assisted EK procedure. The best cutting design remains to be optimized to improve visual results. We have evaluated retrospectively the postoperative evenness of endothelial lenticules (EL) prepared following 2 different cutting procedures.
The thickness of the EL obtained with either double path (group 1, n=7) or double layer (group 2, n=5) procedures were measured using optical coherence tomography, 3 months after being proceeded. A single high resolution corneal quad scan was performed. On each frame, the corneal thickness and the evenness index were measured at the vertex of the cornea (0.0 mm), at 1.5, 3 and 3.5mm away from each side of the vertex. Four central and 8 peripheral measurements were considered for each location and averaged to obtain a mean central thickness (C) and 3 respective mean peripheral thickness (respectively P', P'', P'''). The evenness index was obtained by calculating the C/P ratio. The standard deviation (SD) of the peripheral measurements was used to assess the regularity of the peripheral EL thickness.
C/P' ratio was 0.95±0.05 in group 1 and 1.00±0.02 in group 2 (p=0.19). C/P'' ratio was higher in group 2 than in group 1 (0.89±0.07 vs 0.77±0.06 ; p=0.03) and C/P''' ratio was not significantly different between the 2 groups. Peripheral measurements SD were 11±4µm and 11±3µm, 21±7µm and 11±3µm (p=0.11), 32±16µm and 22±8µm (p=0.31) in the 1.5, 3 and 3.5mm central area in group 1 and 2, respectively.
The double layer procedure seems to provide even and regular EL in the 6-mm central zone compared to two successive lamellar cuts (double path). EL obtained with both procedures are flat in the central 3-mm zone, whereas EL regularity and evenness decrease more peripherally.
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