Purpose: To systematically investigate the central, paracentral, and peripheral endothelial cell density (ECD) in normal human corneas.
Design: Observational case series and experimental study.
Methods: Noncontact specular microscopy was undertaken to determine the ECD of the central, paracentral (2.7 +/- 0.2 mm from center) and peripheral (4.7 +/- 0.2 mm from center) regions of the cornea of 48 normal eyes. The ECDs of central and peripheral regions were also determined with contact specular microscopy in 21 normal eyes and a group of 30 Optisol-GS eye bank corneas were evaluated with alizarin red stain. Histologic ECD of 13 Optisol-GS stored corneas were also determined.
Results: Paracentral and peripheral ECD measured with the noncontact specular microscope were 5.8% (P <.01) and 9.6% (P <.001) increased compared with central ECD. Superior peripheral ECD was increased compared with the other three peripheral quadrants (P <.05) and was 15.9% higher than central ECD. Contact specular microscopy showed an increase of 8.9% in the peripheral ECD from the center. Alizarin red stained corneas confirmed the specular microscopy numbers with a 9.2% increase in the paracentral region, and a 17.2% increase in the peripheral region. Histological cross sections of human corneas also showed a 22.9% increase in peripheral ECD compared with the central region.
Conclusions: The human cornea has an increased ECD in the paracentral and peripheral regions of cornea compared with the central region. The superior peripheral region of the corneal endothelium has the largest increase in ECD. These data on normal endothelial cell distribution in the human cornea are especially significant as they relate to new surgical techniques and endothelial wound repair.