M-K medium and postmortem cytologic damage.

Freshly enucleated rabbit eyes were refrigerated at +4 degrees C under standard eye bank conditions for 2, 6, 9, and 21 days. One group of corneas with a scleral rim were excised and placed in M-K medium, stored for 18, 24, or 48 hr at +4 degrees C; they were then removed, and endothelial cell viability was evaluated with nitroblue tetrazolium. The cells were examined by light microscopy and scanning and transmission electron microscopy. A second group of corneas were similarly obtained and then used as donor corneas from 6 mm transplants. Each recipient rabbit was evaluated daily by slit-lamp biomicroscopy and corneal pachometry. Fourteen days postoperatively, the rabbits were sacrificed, the eyes enucleated, and the excised corneas were evaluated in a fashion similar to those of group 1. M-K medium storage protected the morphology and functional integrity of the rabbit corneal endothelium up to 48 hr beyond moist chamber storage for 2, 6, and 9 days. However, M-K medium appeared to have no such effect on corneas that had been moist chamber--stored for 21 days. These results suggest that some human corneas with a prolonged time from death to moist chamber storage may be utilized for corneal transplantation after further storage in M-K medium.