Corneal preservation at -4 degrees C in a modified tissue culture medium.

Addition of 6% PVP (polyvinylpyrrolidone, mol wt 40,000) to tissue culture medium No. 199 prevents it from freezing at -4 degrees C. Forty donor corneas stored for five and ten days in this medium had a mean thickness of 0.61 and 0.67 mm, respectively. By means of specular microscopy, intact endothelium was found after these storage periods. Epithelial cell layers were histologically present. Electronmicroscopic studies revealed only slight changes in the subcellular endothelial structures. During perfusion with modified Ringer's solution at +34 degrees C, the thickness of stored corneas decreased.