Effects of commercial ophthalmic drugs on rabbit corneal epithelium. A scanning electron-microscopic study.

Surface changes on rabbit cornea were studied by scanning electron-microscopy after instillation of commercial corticosteroid and antibiotic collyria extensively used in ophthalmic practice. All the collyria caused loss of surface microvilli and cell damage. The collyrium containing dexamethasone, neomycin, and benzalkonium chloride caused less damage than similar collyrium with polymyxin, but without dexamethasone. On the other hand the collyrium containing dexamethasone and neomycin was still less damaging than similar collyrium with benzalkonium chloride as preservative. Chloramphenicol with dexamethasone caused damage similar to collyria containing dexamethasone, neomycin, polymyxine B sulphate, and benzalkonium chloride.