Two vital staining techniques, one employing rose bengal and the other Evans blue, are proposed for clinical assessment of donor corneal endothelial viability prior to keratoplasty. Both dyes selectively stained devitalized endothelial cells. Corneal perfusion studies after staining demonstrated that both stains are nontoxic to functioning endothelial cells. These staining techniques provide simple, accurate, and safe methods for evaluation donor tissue prior to corneal grafting.
There is, at present, no clinically available method for accurate and safe assessment of corneal endothelial viability immediately prior to keratoplasty. While vital staining has been widely used for endothelial evaluation in experimental laboratory settings, no vital dye has been proved safe and effective for use on acutual donor corneal tissue prior to transplantation.
The corneal vital stain trypan blue (Stocker, 1973) is unsuitable for use on donor tissue because of its teratogenic properties (Hamburg et al., 1975). Similarly, lissamine green (Jans and Hassard, 1967) cannot be used in clinical settings because of its carcinogenic potential (Registry of Toxic Effects of Chemical Substances, 1975).
We evaluated and compared two vital staining techniques for use in evaluating donor corneal tissue prior to transplantation. The first technique used the vital stain rose bengal, originally introduced by this laboratory for experimental evaluation of corneal endothelial viability (Peyman and Spence, 1977). The second technique employed the vital stain Evans blue, and acid dye of the diazo group, which has never before-been used to assess corneal endothelial status. In this investigation, both dyes were tested against the two criteria that a vital stain for clinical use must meet: (1) the stain must be sufficiently sensitive and selective to detect increasing endothelial devitalization with increasing time of tissue refrigeration, and (2) the dye must be nontoxic to the functioning of viable endothelial cells and must be free of systematic toxicity as well.