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From the Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong (VJ, TCYC, WYL, KL, PY, YWYY, YW, TKN); Hong Kong Eye Hospital, Mongkok, Kowloon, Hong Kong (VJ, TCYC); the Department of Ophthalmology, College of Veterinary Medicine & Surgery, University of Missouri-Columbia, Missouri (RRL, SSC, RRM); the Department of Mathematics and Statistics, Hang Seng Management College, Hong Kong (MCYY); Harry S. Truman Memorial Veteran Hospital, Columbia, Missouri, (RRM); and Mason Eye Institute, University of Missouri-Columbia, Missouri (RRM).
Supported by Direct Grant No. 4054026, Chinese University of Hong Kong, Hong Kong.
The authors have no financial or proprietary interest in the materials presented herein.
The newer generations of femtosecond lasers have used for creation of inverted side-cuts during LASIK. 1,2 It has postulated that side-cut angulation with the stromal flap diameter exceeding its epithelial diameter could enhance corneal biomechanics after femtosecond laser-assisted LASIK in in vivo animal and ex vivo human corneas. 1,3 Several reports have suggested increased biomechanical strength of flap adhesion, 1,3 and superior recovery of corneal sensation in corneas receiving LASIK with the inverted side-cut. 4 Conversely, we have reported that the corneal biomechanical properties were not enhanced in LASIK flaps with an inverted side-cut angle using the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Depew, NY) at 1 and 3 months after femtosecond laser-assisted LASIK. 2 Furthermore, there are no reports available for the differences in the histology and cellular changes in the corneal flaps created with conventional and inverted side-cut angles.
Early events in corneal wound healing are particularly critical in effective recovery of patients from corneal incisional surgeries. 5,6 Keratocyte proliferation, infiltration, and stromal cell death are initial responses observed in postoperative corneas. 7-9 The current study was undertaken to investigate the in vivo changes in epithelial cell ingrowth, keratocyte proliferation, and apoptosis in rabbit corneas following femtosecond laser-assisted LASIK using conventional (70[degree]) or inverted (115[degree]) side-cut angles. In addition, we also evaluated the long-term effect of side-cut angle profile on the changes in corneal biomechanical measurements in human patients following femtosecond laser-assisted LASIK.
Materials and Methods
Rabbits
Twenty-four female New Zealand albino rabbits (12 to 15 weeks of age) weighing 2.5 to 3 kg were obtained from the Laboratory Animal Service Center of...