A new medium for the storage of donor eyes for corneal grafts.

THE EXPANSION of modern keratoplasty has increased the demand for suitable donor eyes, but for obvious reasons supplies are limited. This shortage has stimulated research into the best methods of preserving and storing donor eyes in order to eliminate any preventable factors which may be responsible for loss or wastage of this precious material. Although it is not a universal practice, in this Corneo-Plastic Unit, no donor eye is used unless contamination by pathogenlc bacteria has been absolutely excluded. During the period January, 1955, to June, 1956, 51 (41.3 per cent.) out of 138 post-mortem eyes, donated to this Bank for corneal grafting and stored in sterile liquid paraffin, were found on culture to be contaminated and unsuitable for use. The organisms isolated belonged to the staphylococcal, coliform, proteus, and corynebacterium groups. Contamination with a penicillin-sensitive strain of Staphylococcus albus is not regarded as a bar to the use of an eye for corneal grafting. The high incidence of wastage through bacterial contamination in addition to the general shortage caused concern and prompted an investigation to find a more suitable storage medium than sterile liquid paraffin. The use of antibiotics was explored, but it was found that immersion of an enucleated eye for a short period in an antibiotic solution would not necessarily guarantee sterility. Moreover, on account of the high proportion of resistant bacteria, the use of penicillin was abandoned as unsafe. A combination of chloramphenicol. and streptomycin has been found to give the most consistently satisfactory results when used in concentrations of 1,000 jug. per ml., but even then it is essential for the eye to be in contact with the antibiotics for at least 48 hours. This is presumably due to the time required for the antibiotics to penetrate to the deeper structures of the eye. *The criteria for the physiological requirements of corneal storage described by Davson (1955) formed the basis of the investigation which has resulted in the development of a new medium. After being stored for 14 days in