title: Connection of histological corneal endothelial cell count with endothelial cell density before penetrating keratoplasty.
abstract: OBJECTIVE
  Corneal endothelial cell density and the integrity of the monolayer are essential for maintenance of a clear cornea. In 1992, Williams et al. introduced a method to estimate the endothelial cell density in histopathologic examination. It would enable an evaluation of the corneal host endothelium, even if preoperative measurement was not possible. The goal of this study is to evaluate the accuracy of the Williams equation in corneal buttons obtained from penetrating keratoplasties.
  
  
  METHODS
  High power field (HPF) photographs and histological endothelial cell counts were made from the corneal endothelial cells of each corneal histopathological cross-section. We then compared the calculated endothelial cell density using the Williams equation with the preoperative measured endothelial cell density. A bivariate regression analysis of the histological HPF cell counts and the preoperative endothelial cell density count was also performed.
  
  
  RESULTS
  The equation of Williams et al. overestimates the endothelial density in all of our patients. Linear regression showed a strong relation between the central histological HPF count and the preoperative endothelial cell density. The regression formula for the endothelial cell density is 59.66 + (272.447 × HPF count); p < 0.001, R2= 0.901.
  
  
  CONCLUSIONS
  This study confirms the relation between the corneal endothelial cell density, measured with specular microscopy, and the histopathological endothelial cell count in a HPF. However, the equation of Williams et al. provides an overestimation of the endothelial cell density. To proper utilize the histopathological endothelial cell count, a calibration of the equation coefficients in the local setting is necessary to prevent systematic errors.
authors: Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany. stefan.lang@uniklinik-freiburg.de.
authors: Stefan J
authors: SJ
authors: Lang
authors: Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany.
authors: Anja
authors: A
authors: Freysoldt
authors: Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany.
authors: Daniel
authors: D
authors: Böhringer
authors: Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany.
authors: Thomas
authors: T
authors: Reinhard
authors: Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Killianstr. 5, 79106, Freiburg, Germany.
authors: Claudia
authors: C
authors: Auw-Haedrich
mesh_terms: D002452:Cell Count; D004728:Endothelium, Corneal / Q000473:pathology*; D006801:Humans; D007640:Keratoconus / Q000473:pathology* / Q000601:surgery; D015948:Keratoplasty, Penetrating; D057234:Preoperative Period
keywords: Corneal endothelium; Endothelial cell density; Keratoplasty; Ophthalmic pathology