Cytotoxicity of gentamicin on corneal endothelium stored in vitro.

Since corneas are preserved in storage media containing gentamicin, the risk of gentamicin toxicity could increase with the increase in the storage time as well as with the increase in the concentration. We wished to determine the safety level of gentamicin on the corneal endothelium in terms of its concentration as a function of the storage time. One cornea (experimental) of a rabbit was stored in chondroitin sulfate medium (CSM) containing 0.5 mg/ml or 1 mg/ml of gentamicin, and the other cornea (control) was kept in CSM containing 0.1 mg/ml of gentamicin. Both corneas were stored up to 14 days at 4 degrees C. After storage, each corneal endothelium was studied by specular microscopy, light microscopy (following staining with trypan blue and alizarin red) and transmission electronmicroscopy. In comparison with the control corneas, the experimental corneas showed progressively greater amounts of endothelial cell damage, as the concentration of gentamicin or the storage time was increased. Our morphological study indicates that the presently recommended concentration of gentamicin (0.1 mg/ml) is not cytotoxic to the corneal endothelium provided the time of storage does not exceed 7 days.