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D. T. Tan, J. S. Mehta, Y. M. Por, H. Cajun-Uy, A. Parasarthy, R. W. Beuerman; Comparison of Posterior Stromal Bed Dissection: Microkeraome vs. Femtosecond Laser. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1149.
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Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) requires posterior lamellar donor preparation with use of a microkeratome-artificial chamber device. We developed a procedure to prepare the lamellar donor tissue, using the femtosecond laser. This study evaluates donor surface bed morphology following formation by femtosecond laser compared to microkeratome.
Femtosecond laser algorithms utilizing the FEMTEC laser were developed to perform a 7.5mm diameter posterior lamellar dissection at 150 microns from Descemet’s membrane, with a peripheral rim cut enabling complete detachment of the posterior lamella. 40 human eye bank corneas were used; 10 received single lamellar ablation pass, 10 a double pass and 10 a triple pass, at the same optimized laser parameters. 10 corneas were dissected using standard microkeratome. Subjective clinical grading; ease of rim separation, posterior lamellar separation was performed by a single observer. Tissues were fixed and processed for SEM (JEOL JSM-5610LV) and Atomic force microscopy using a standard protocol. Masked independant observers graded the SEM images of stromal bed of the donor disc from 1(poor) to 4(excellent) for surface smoothness. RMS values were calculated from AFM.
Single pass ablations resulted in poor donor separation in contrast to double and triple pass ablations . Triple pass ablations were marginally superior to double in the ease of separation. Mean score of SEM for the stromal bed of the donor disc was 4 for double/triple pass and 2.25 for single pass (p=0.046) and 2.4 for Microkeratome cut (p<0.05 v single pass, p=0.02 v double/triple pass ablation). RMS values from AFM collobarated the SEM findings in that double/triple pass lamellar bed morphology was superior to that of a single pass and micokeratome beds.
Femtosecond lasers can be used to prepare the donor corneal lamellae for DSEK. Double and triple pass lamellar ablations provide good bed surface quality and a significant improvement on current microkeratome dissection. Smoother lamellae dissection may improve interface quality between graft and host and hence visual results.
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