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M. Lombardo, G. Lombardo, D. Friend, S. Serrao, M. A. Terry; Biomechanical Response of the Cornea to Large-Incision Deep Lamellar Endothelial Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1939.
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To analyze the response of the cornea to large-incision deep lamellar endothelial keratoplasty (DLEK) during a 2 years follow-up.
The Orbscan topographies of twelve eyes from twelve patients that underwent large-incision DLEK technique were retrospectively analyzed. The preoperative and 1-, 3-, 6-, 12- and 24-months postoperative corneal raw data were imported into a custom software program which computed the average composite corneal maps and difference maps in order to evaluate the corneal response to the surgery. The software delineated two concentric zones to characterize the postoperative regional remodeling of the cornea: the central and peripheral regions.
At two years after surgery, no significant steepening (0.83 D; Student t-test, P>.05) of the central surface topography has been measured in compare with the preoperative state. Also, a minor increase (P>.05) in the central keratometric astigmatism, less than 0.15 D, has been assessed at the end of follow-up. The average posterior central tangential map did not significantly differ from before surgery, with curvature changes less than 0.25 D (P>.05). However a significant increase (>0.65 D, P<.05) in the average posterior central astigmatic power of the cornea was found. A significant steepening (2.42 D, P<.05) of the peripheral anterior cornea has been noticed, with a significant increase in the peripheral astigmatism power of 1.81 D (P<.05). Major changes occurred between 12- and 24-months after surgery. On the other hand, no significant remodeling of the posterior peripheral cornea has been measured. The corneal tissue thinned significantly (P<.05) during follow-up.
The DLEK procedure effectively preserves the preoperative keratometric corneal topography, minimizing changes in curvature and astigmatism of the cornea. The great predictability of corneal topography following DLEK is likely to be attributed to the minimal biomechanical changes that occur in the anterior stroma, the portion of the cornea that appears to be mainly responsible for maintenance of corneal shape. Moreover, the donor posterior cornea shows to maintain its integrity and optical performance in the long-term postoperative period.
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