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P. Scaroni, R. Leaci, D. Dallatana, A. Neri, L. Fontana, C. Macaluso; Deep Stromal Dissection for Endothelial Keratoplasty Obtained With a Femtosecond Laser and a Microkeratome With Different Head Advancement Speeds. A Scanning Electron Microscopy Study. Invest. Ophthalmol. Vis. Sci. 2010;51(13):764.
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© ARVO (1962-2015); The Authors (2016-present)
To explore the surface quality of deep stromal dissections in bank eyes obtained with either a femtosecond laser or a microkeratome used with three different head advancement speeds.
Twelve sclerocorneal donor buttons not adequate for human trasplantation were mounted on an artificial chamber. Three corneas were dissected with a 1000 KHz femtosecond laser (Femto LDV, Ziemer, Switzerland) at 400µm depth (FEMT group). Nine corneas were dissected with a Microkeratome (Carriazo-Barraquer, Moria, France) mounting a 300µm cutting head. In three cases head advancement over the cornea was completed in 2-4 seconds (FAST group), in three cases in 8-10 s (MED group), in three cases in 18-20 s (SLOW group). Following routine preparation, all endothelial buttons were analyzed with a scanning electron microscope (SEM 501, Philips, Germany) at 20X, 40X, and 160X magnifications.
The stromal surface of the endothelial buttons of the FEMT group showed a generally excellent smoothness, but with some small areas that were rough and irregular. Differently from the FEMT group, all microkeratome dissected endothelial buttons failed to show significant variations in smoothness across the cut surface. While the surface of the MED and of the SLOW groups were regular, the FAST group showed a rougher surface. The smoothness obtained in the best areas of the FEMT group was unmatched by the surfaces obtained in any of the microkeratome groups.
Microkeratome dissection of endothelial corneal buttons resulted in consistent regular cut surfaces, but it is advisable to complete the head movement rather slowly, in at least 8-10 seconds. Femtosecond laser technology has the potential for generating endothelial corneal buttons with extremely smooth surfaces, even better than those that can be obtained with a microkeratome. Nevertheless, the deep stromal location of the cut may limit the overall regularity of the dissected surface. It is conceivable that the suboptimal optical properties of rejected eye bank tissues could have heavily contributed to this problem, limiting proper laser focusing in the deep stroma.
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