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Lee Katzman, Yousuf M Khalifa, Caroline Hoover, Bennie H Jeng; An Assessment of the Accuracy and Cut-Failure Rates of Eye Bank-cut Corneas for Use In Endothelial Keratoplasty; A Comparison of Outcomes Between 2010 and 2013. Invest. Ophthalmol. Vis. Sci. 2014;55(13):879.
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Eye bank-prepared corneas for endothelial keratoplasty have been shown to be a cost-effective and viable alternative to surgeon-cut tissues. The purpose of this study was to evaluate the accuracy of eye bank-prepared pre-cut donor corneas over time by comparing cut-failure rates and corneal thickness measurements from 2,501 specimens in 2010 and 2013.
2,501 human corneas cut by a technician-operated mechanical microkeratome intended for posterior lamellar keratoplasty were evaluated in a prospective manner at one large eye bank facility in 2010 and in 2013. The endothelium was evaluated by slit lamp and specular microscopy both before and after cutting was initiated. Graft thickness as measured by pachymetry and/or optical coherence tomography was collected to assess the accuracy of the cut tissue. Cut failure rates were compared between normal donor tissue and tissue with significant preexisting scarring (e.g. LASIK or PRK scarred corneas), but still appropriate for endothelial transplantation. Data was further stratified by the etiology of cut failure: excess graft thickness or unevenness, endothelial problems identified pre-cut, endothelial problems identified post-cut, and perforations.
The combined cut failure rate (normal tissue and scarred tissue) in 2010 and 2013 was 2.3% (23 of 1000 corneas) and 1.6% (24 of 1501 corneas), respectively (p=0.10). The cut failure rate among normal tissue in 2010 and 2013 was 2.05% (19/927) and 1.36% (19/1400), respectively (p=0.099). The cut failure rate among previously scarred tissue in 2010 and 2013 was 5.48% (4/73) and 4.50% (5/111), respectively (p=0.38). The average surgeon-requested graft thickness (in microns) in 2010 and 2013 was 150 and 127.24, respectively, with an average achieved thickness of 140.01 (SD 16.32) and 125.08 (SD 12.46), respectively (p=0.023).
The combined cut failure rates, also interpreted as the corneal tissue wastage rates, trended towards improvement from 2010 to 2013 despite failing to reach statistical significance. The failure rate is even less when considering the rate among normal, non-scarred tissue. The accuracy of graft thickness, however, did improve from 2010 to 2013 (p<0.05). This study suggests that the accuracy and success rates of tissue preparation for endothelial keratoplasty improves with experience and volume.
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