Treatment of bacterial ulcers of the cornea in the rabbit: a comparison of administration by eye drops and subconjunctival injections.

The various routes of antibiotic administration available to treat a bacterial corneal ulcer were reviewed and compared, and the pharmacokinetics and efficacy of each route analyzed in the rabbit. I then evaluated the efficacy of eye drops and subconjunctival injections in the treatment of bacterial corneal ulcers for each of the following drug-organism combinations: staphylococcal ulcers/cefazolin, staphylococcal ulcers/gentamicin and Pseudomonas ulcers/gentamicin. Both topical and subconjunctival administration of each drug effectively reduced or eliminated the bacteria from infected corneal tissue. For both cefazolin and gentamicin, the subconjunctival and the topical route were of similar efficacy in the treatment of Staphylococcal and Pseudomonal ulcers. Subconjunctival injections produced high but transient peaks followed by persistent low troughs for both drugs. In contrast, eye drops produced moderate but sustained concentrations throughout the treatment period. Under the circumstances studied, it appears that transient high peaks are not needed to eliminate bacteria effectively from a bacterial corneal ulcer. Since both routes are equally effective, other factors should determine the preferred route.