Corneal epithelial permeability after instillation of ophthalmic solutions containing local anaesthetics and preservatives.

The effect of the local anaesthetics oxybuprocaine (OBu) and tetracaine (Tetra) and the preservatives chlorhexidine (CH) and benzalkonium chloride (BAK) on corneal epithelial permeability was studied by fluorophotometry in normal human eyes. Five instillations of one drop ophthalmic solution of the compounds were administered to one eye at 2-minute intervals; a control solution was instilled into the fellow eye. The increase in corneal epithelial permeability, expressed as the permeability ratio between the treated and control eye, was not significant after instillation of the anaesthetics. The preservatives and the combination OBu + CH increased corneal epithelial permeability significantly (P less than 0.05). OBu + BAK and Tetra + BAK increased permeability to a far greater extent (P less than 0.005).