Decreased Corneal Endothelial Cell Density After Osmotic Stimulation With Sucrose

Abstract

Abstract: : Purpose: To evaluate the effects of osmotic stimulation on corneal endothelial cell density with 1.8% sucrose solution and hypo–osmotic balanced salt solution (BSS). Methods:Two groups of paired central discs from pig corneas with a diameter of 8.0 mm were organ cultured for 24 hours at 37°C in MEM with 2% FCS. Six corneas per group were exposed to 1.8% sucrose solution or to hypo–osmotic BSS for 4 minutes each. The paired corneal discs were not treated and served as controls. After further organ culture for 48 hours corneal endothelium was stained with alizarin red S and examined by light microscopy. Three central images were obtained and digitalized using the NAVIS software (Nidek Technologies, Italy). The endothelial cell densities were determined manually on all three images by one experienced investigator using the fixed–frame method. Results:The difference in endothelial cell density between corneas stimulated with 1.8% sucrose and the control corneas was statistically significant (p=0.003) (3982±371cells/mm² and 4360±322 cells/mm² respectively). The average difference between the treated corneas and the controls in the sucrose group was –377 cells/mm² with a range from –222 to –673 cells/mm². In contrast the difference in endothelial cell density between corneas stimulated with hypo–osmotic BSS and the control corneas was not statistically significant (p=0.411) (4374±288 cells/mm² and 4317±188 cells/mm² respectively). The average difference between the treated corneas and the controls in the hypo–osmotic BSS group was +56 cells/mm² with a range from +316 to –83 cells/mm². Conclusions: Osmotic stimulation with 1.8% sucrose for 4 minutes induces a significant endothelial cell loss of 9% on average. The same stimulation with hypo–osmotic BSS has no influence on the endothelial cell density. Endothelial cell evaluation of organ cultured donor corneas should be performed with hypo–osmotic BSS rather than sucrose.

Keywords: cornea: endothelium • clinical laboratory testing • ocular irritancy/toxicity testing