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J. M. Freeman, D. E. Ward, J. Gary, Z. A. Karcioglu, Z. A. Karcioglu; Morphologic Observations by Electron Microscopy of the Posterior Stroma Following Deep Lamellar Flaps With Made With the Femtosecond Laser and Mechanical Microkeratome. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4698.
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© ARVO (1962-2015); The Authors (2016-present)
To describe morphologic features of the posterior stroma following deep lamellar flaps fashioned by the femtosecond laser (FSL) versus microkeratome and compare these findings to the morphology of "Descemet’s stripping".
Six eye bank corneoscleral buttons (CSB) were used. On three CSBs he femtosecond laser (IntraLase Corp., Irvine, CA) was used to create anterior flaps of 400 um thickness on an Barron artificial chamber device (Katena ). The FSL cuts were made with an energy level of 4.0 µJ with a spot separation of 6 microns. Three different laser patterns were used: spiral(S), raster(R), and spiral plus raster (SR). Microkeratome flaps were performed on 2 CSBs with a Moria LSK-1 with a head size of 250 microns. Three specimens obtained from different laser cuts, 1 specimen from microkeratome cut and 1 specimen from "Descemet’s stripping" were examined by scanning electron microscopy with a Philips XL 30 ESEM.
The side cuts of the stroma with the FSL were very uniform and formed about 90 degrees to the base of the flap. The side cut of the microkeratome flap was sloped and irregular. In contrast the stromal bed of the microkeratome produced flap was smooth and more regular when compared to all of the FSL cuts. Among the FSL cuts, the stromal bed fibers produced with raster mode had a more haphazard, jagged appareance than that produced in the spiral mode. The stromal bed fibers produced with both raster and spiral modes had a similar appearance as those produced with the spiral only mode.
While the femtosecond laser has become broadly accepted as safe and effective for anterior lamellar corneal procedures, its potential for posterior lamellar corneal procedures is only now being explored. This pilot study suggests that the stromal bed surface in FSL deep lamellar cuts is more irregular than that produced with mechanical microkeratome. The irregular surface may have different implications for the visual performance of posterior lamellar procedures than that for anterior lamellar procedures. Adjustments in energy level, spot separation, laser pattern, and applanation technique offer potential parameters that may be adjusted to produce better results.
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