Purchase this article with an account.
C.B. Nau, J.W. McLaren, L.J. Maguire, S.V. Patel, W.M. Bourne; Keratocyte Density After LASIK: Does Cutting the Flap With a Femtosecond Laser Make a Difference? . Invest. Ophthalmol. Vis. Sci. 2006;47(13):542.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine if keratocytes are lost at a different rate after LASIK with the flap cut by a femtosecond laser than after LASIK with the flap cut by a microkeratome.
Twenty patients received bilateral LASIK to correct myopia and myopic astigmatism. One eye of each patient was randomized to receive a planned 180–µm flap cut by using a microkeratome (Hansatome, Bausch & Lomb, Rochester, NY), and the other eye received a planned 120–µm flap cut with a femtosecond laser (Intralase FS, Intralase Corp., Irvine, CA). Corneas were examined by confocal microscopy (Tandem Scanning, Reston, VA) before, and at 1, 3, and 6 months after surgery (13 patients were examined at 6 months). Cell densities were determined by using an automated cell counting program in selected frames of the anterior and posterior halves of the flap, the anterior and posterior halves of the 100–µm region posterior to the interface, the posterior third, and posterior 10% of the stroma. Cell densities in each layer were compared between treatments at each exam by using paired t–tests and Bonferroni correction for 4 repeated measures.
Before surgery, the unweighted mean keratocyte density through the stroma was 26,815 ± 2,165 cells/mm3 (mean ± SD) in the corneas that would be cut by the femtosecond laser and 26,253 ± 3,114 cells/mm3 in the corneas that would be cut by the microkeratome (p = 0.40). In the laser–cut corneas, cell densities at 1, 3 and 6 months were 26,622 ± 1,967 cells/mm3, 25,709 ± 3,381 cells/mm3, and 25,119 ± 3,035 cells/mm3 respectively. The respective densities in the microkeratome–cut corneas were 26,205 ± 3,597 cells/mm3, 26,595 ± 3,257 cells/mm3, and 24,669 ± 2,893 cells/mm.3 At each examination, cell densities in all layers of corneas cut with the laser were not significantly different from those in corneas cut with the microkeratome (p > 0.16). The average minimum detectable difference was 4,992 cells/mm3 (α = 0.05/4, ß = 0.8, paired t–test).
During the first 6 months after LASIK, cell density in the corneal stroma is not different when the flap is cut with a femtosecond laser than when the flap is cut with a microkeratome.
This PDF is available to Subscribers Only