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H. B. Hindman, R. L. McCally, A. Kim, S. D'Anna, C. G. Eberhart, A. S. Jun; Evaluation of the Effects of Circular Descemet's Membrane Incision on the Biomechanical, Topographic, and Optical Properties of Rabbit Corneas. Invest. Ophthalmol. Vis. Sci. 2008;49(13):672.
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The structural or functional role of Descemet’s membrane is not well understood nor are the short-term or long-term effects of incising this tissue. Yet endothelial keratoplasty procedures, which utilize the Descemetorhexis, are growing in popularity among corneal surgeons world-wide. The purpose of our investigation was to characterize changes in the structural, biomechanical, and optical properties of the cornea induced by circular Descemet’s membrane incision in rabbit corneas.
Three separate intervention groups were created using New Zealand White rabbits: (1) left eyes of 18 rabbits were assigned to a receive an 8.5 mm Descemet’s scoring procedure with a reverse Sinskey hook, (2) left eyes of an additional 10 rabbits were assigned to the placement of 2 paracenteses identical to those placed for group 1, and (3) right eyes of these 10 rabbits were assigned to medical treatment with topical antibiotic and steroid medications identical to the postoperative care of the other two groups. Following administration of anesthesia, scatterometry, corneal hysteresis, pachymetry, and keratometry measurements were performed prior to and two weeks following the interventions. Four normal eyes and four eyes that had undergone Descemet’s scoring were enucleated post-mortem and evaluated by histology and transmission electron microscopy.
Eyes that had undergone Descemet’s scoring procedures were found to have significantly decreased corneal power post-operatively as measured by mean keratometry (43.9 + 0.7 diopters (mean + S.D.) pre-operatively vs. 43.5 + 0.9 diopters post-operatively, p = 0.007). Circular Descemet’s scoring did not significantly change corneal hysteresis (4.4 + 1.1 mm Hg pre-operatively vs. 4.6 + 0.9 mm Hg post-operatively, p = 0.664). Corneal light scattering was decreased after Descemet’s scoring (0.00254 + 0.00059 pre-operatively vs. 0.00206 + 0.00031 post-operatively, p = 0.0025). Pachymetry measurements were found to remain relatively stable (341.3 + 18.6 µm pre-operatively vs. 330.6 + 20.0 µm post-operatively) without significant post-operative edema.
Circular Descemet’s scoring was found to flatten the corneal curvature by a mean of 0.4 diopters and reduce corneal light scattering without affecting corneal hysteresis or corneal thickness. These findings have important implications for ongoing developments in endothelial keratoplasty.
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