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Brad Gray, Ling C. Huang, Li Chen, Zsolt Bor, Jaime R. Martiz, Michael Brownell; Corneal Biometry Analysis Following Femtosecond Laser-Assisted Intrastromal Keratotomy in Rabbit Eyes. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5763.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously established the baseline corneal biometric measurements in rabbits as a useful pre-clinical model for evaluating refractive technology (Gray B, et al. IOVS; 51:ARVO E-Abstract 4200). Here we present the initial results of femtosecond laser-assisted intrastromal keratotomy (FLISK) induced corneal biometry changes along with refractive error and higher order aberration (HOA) analysis in a rabbit model.
Thirteen Dutch Belt rabbit eyes (approx. 6 months old) underwent FLISK. The Pentacam HR Scheimpflug camera (Oculus) was used to analyze keratometry and corneal pachymetry. Corneal histopathology was evaluated by light microscopy. Wavefront aberrometry was measured using Wavescan (AMO). Comparison of pre- and post-operative changes up to 1 month was based on the same pupil size (5mm) for HOA. HOA from 49 naive rabbit eyes were compared to results from 719 human eyes.
Analysis by Pentacam showed central and overall corneal thinning (central 5-52 µm, overall 8-39 µm) while the K1 keratometry value increased by (0.2 to 4.6 D) following FLISK. Histology showed treatment dependent healing patterns at the sites of laser incision. Spherical refraction in the treated eyes consistently shifted toward more negative values (n=13). The RMS (root mean square) of HOA increased 55.97% and 95.59% at 1 week and one month, respectively. Average spherical and cylinder power in the rabbit eyes were +1.32 ± 0.77 DS and -0.98 ± 0.63 DC, respectively (n=49). With the exception of spherical aberration, HOAs in rabbit eyes appeared to be larger than those observed in human eyes but decreased with pupil size similar to that in humans. Wavefront error RMS of HOA in rabbit eyes is 2 times larger than that in human eyes.
Results from this study demonstrated considerable post-operative changes in terms of corneal biometry and histopathology (wound healing) in FLISK-treated eyes. The Wavefront measured differences in HOAs provide useful insight into the anatomical comparisons between rabbit and human eyes. Additional studies are warranted to evaluate the safety and efficacy of femtosecond laser-assisted intrastromal keratotomy treatment paradigm for laser vision correction.
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