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M. Rauen, K. M. Goins; Impact of Previous Cataract Surgery in Donor Corneas Used for Endothelial Keratoplasty: Is There Support for a Two-Hit-Hypothesis?. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2332.
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© ARVO (1962-2015); The Authors (2016-present)
Endothelial keratoplasty (EK) offers advantages over penetrating keratoplasty, and utilization of this procedure is increasing. However, the donor, recipient, and perioperative conditions that impact endothelial cell loss over time have not totally been elucidated. Cataract surgery has been associated with both an immediate and a sustained corneal endothelial cell loss that is greater than normal attrition with aging. This study assesses the rate of endothelial cell decay in pseudophakic donors after EK.
A retrospective review was performed on patients who have undergone deep lamellar endothelial keratoplasty (DLEK) and Descemet’s stripping automated endothelial keratoplasty (DSAEK) at the University of Iowa between 12/03 and 03/07. Eleven patients underwent EK utilizing tissue from pseudophakic donors. Three patients underwent small incision DLEK, and eight patients underwent DSAEK. Mean donor age was 64 years. The mean death to preservation interval was 5 hours and 34 minutes. The mean time in Optisol GS was 3.3 days. The mean preoperative donor endothelial cell density (ECD) for pseudophakic donor tissue was 2918 cells/mm2 (n = 11). All DLEK grafts were surgeon cut with the Moria ALTK or with manual dissection, while all DSAEK grafts were precut from the Iowa Lions Eye Bank.
Postoperatively, one DLEK and one DSAEK eye were classified as graft failures unrelated to donor tissue, thereby necessitating re-graft. In the remaining eyes using pseudophakic donor tissue, there is a mean ECD at 6 months of 989 (±345) cells/mm2 after DLEK (n=2) and 1369 (±-627) cells/mm2 after DSAEK (n=7). In comparison, our non-pseudophakic donors had an ECD of 1869±489 cells/mm2 after DLEK (n=72). When comparing eyes undergoing EK utilizing pseudophakic donor tissue to those of non-pseudophakic donors, there is a statistically significant decrease in ECD at 6 months in eyes transplanted with pseudophakic donors (P=0.00248).
Compared to the endothelial cell loss after small incision DLEK at our institution (37% at 6 months), the rate of endothelial cell loss in EK with the use of pseudophakic donors is slightly higher (61% at 6 months). We introduce the concept of a Two-Hit Hypothesis to explain the trend toward more rapid endothelial cell decay in eyes using pseudophakic donors. In regards to endothelial cell insult, the donor’s cataract surgery constitutes "hit one" with the recipient’s EK constituting "hit two." Additional evaluation into the donor, recipient, and perioperative conditions are needed for optimization of this novel method of endothelial replacement.
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