Antimicrobials and the corneal endothelium

The effects of various intraocular antibiotics and preservatives on the rabbit corneal endothelium were evaluated using vital staining, light, scanning, and transmission electron microscopy after topical application of the drugs and up to 2 days following anterior chamber injection. Benzalkonium chloride consistently produced the most severe and probably irreversible damage. Some changes which persisted for 2 days were found with methicillin. Gentamicin produced a moderate amount of cellular edema which disappeared after 2 days. Minimal changes were produced by dexamethasone and amphotericin B. Although these results should not be directly interpolated to the human situation, the face that some of these agents did produce changes in the rabbit corneal endothelium, which is well known to be heartier than human endothelium, indicates that caution should be taken when one considers injecting antibiotics intraocularly.