Ultrastructural changes to the corneal endothelium due to benzalkonium chloride

Ten normal and 20 keratectomised corneas received hourly drops of vehicle with or without benzalkonium chloride (0.02% BAC or 0.01% BAC plus 0.1% disodium ethylenediaminetetraacetate) over the daylight hours of 2 days (18 applications). When applied to the intact cornea, BAC with or without Na2EDTA caused only slight clarification of the endothelial cytoplasm, whilst in a few mitochondria the cristae were displaced. In the keratectomised corneas receiving BAC, the majority of mitochondria of the central endothelial cells were pale and swollen or even disrupted. Many contained aggregations of membranous material either within the mitochondrion or at its outer membrane. The peripheral endothelium was much less affected than the central area of endothelium behind the keratectomy. These results suggest that BAC should not be administered to corneas in which the anterior epithelial barrier is incomplete.