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S. E. Wilson, F. W. Medeiros, H. Kaur, V. Agrawal, S. S. Chaurasia, W. J. Dupps, Jr.; Effect of Femtosecond Laser Energy Level on Corneal Stromal Cell Death and Inflammation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2963.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the effect of femtosecond laser energy level on stromal cell death and inflammatory cell influx during the early corneal wound healing response following flap creation in a rabbit model.
Eighteen rabbits were stratified in three different groups (n=6 for each group) according to level of energy applied for flap creation (six animals per group). Three different energy levels of a 60 KHz femtosecond laser (Intralase, Irvine, CA) were chosen for both the lamellar and side cut: 2.7 µJ (high-energy), 1.6 µJ (intermediate-energy) and 0.5 µJ (low-energy). The opposite eye of each rabbit served as a control. At the 24 hour time point after surgery, all rabbits were euthanized and the corneoscleral rims were removed cryo-fixed in OCT. Levels of cell death and inflammatory cell influx were detected with TUNEL and CD11b immunocytochemistry assays, respectively, and the number of labeled cells/400X microscope field were counted. The TUNEL assay has been previously shown to detect both apoptosis and necrosis in the early postoperative period following femtosecond laser flap formation.
The high-energy group (31.9+/-2.9 [SEM]) had significantly more TUNEL positive cells compared to the intermediate (22.2+/-0.8, p=0.004), low (17.9+/-1.6, p=0.001) and control eyes (0.6±0.009, p=0.001). The intermediate- and low-energy groups had more TUNEL-+ cells than control eyes (p=0.001), but the difference between the intermediate and low levels was not significant (P=0.56). Mean ± SEM for CD11B+ cells/400X field was 26.1±11.9, 5.8±1.6, 1.6±1.6, and 0.005±0.005 for high, intermediate, low and control groups, respectively. Only the high-energy group showed statistically more inflammatory cells than control eyes (P=0.039).
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