Corneal endothelial cell loss after nonmechanical penetrating keratoplasty depends on diagnosis: a regression analysis
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Purpose. To assess the impact of diagnosis on corneal endothelial cell loss after nonmechanical penetrating keratoplasty (PK) with regression models.
Methods. Five hundred eighty-nine eyes [273 with keratoconus (group I; PK only), 187 with Fuchs' endothelial dystrophy (group II; 77 PK only and 110 triple procedures) and 129 with bullous keratopathy (group III; 115 pseudophakic and 14 aphakic eyes)] were included in this prospective study. The time course of the endothelial cell density after PK was assessed by specular microscopy. Endothelial cell density was analyzed in cross-sectional fashion at 6 and 24 months follow-up and in longitudinal manner (follow-up 2.4±1.8 years) with linear and exponential regression models (minimizing the residuum between observed and predicted endothelial cell count). Donor age, post-mortem time, storage time and ratio of organ-cultured to short-term-preserved donor corneas did not differ significantly between groups of patients.
Results. In a cross section, endothelial cell density in group I / group II / group III decreased from 1,959±499 / 1,524±528 / 1,526±670 cells/mm2 to 1,617±553 / 1,222±520 / 1,063±384 cells/mm2 (P=0.06 / 0.04 / 0.005). Endothelial cell count was significantly higher in group I than in group II (P=0.048) and significantly higher in group II than in group III (P=0.01) at 24 months. In the linear regression model, cell count decreased in group I / group II / group III by 136±465 / 241±374 / 421±484 cells annually. In the exponential regression model, cell count decreased in group I / group II / group III by 2.9±28.0% / 11.2±21.8% / 19.3±29.4% annually. Cell loss was highly significantly lower in group I than in group II (P<0.0001) and highly significantly lower in group II than in group III (P<0.0001).
Conclusion. Endothelial cell loss seems to be least pronounced after PK in keratoconus (2.9%), followed by Fuchs' dystrophy (11.2%) and bullous keratopathy (19.3%). These differences between diagnoses indicate migration of endothelial cells along a density gradient after PK.
KeywordsKeratoconus Corneal Endothelial Cell Endothelial Cell Density Penetrate Keratoplasty Endothelial Cell Loss
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