Topical and subconjunctival therapy with gentamicin sulfate were compared in rabbits following the induction of Pseudomonas and lye corneal ulcers. The concentrations of antibiotic in the cornea were significantly higher with the subconjunctival than with the topical route for Pseudomonas ulcers. In the case of lye ulcers, however, the difference was not statistically significant. Therapeutic levels of gentamicin were maintained in corneal ulcers for at least six hours after a subconjunctivally given injection. In contrast, less than 1μg of the agent was detectable per gram of cornea one hour after cessation of topical application. This study suggests that bacterial ulcers of the cornea might best be managed with a combination of subconjunctival and frequent topical treatment.
Baum JL, Barza M, Shushan D, Weinstein L. Concentration of Gentamicin in Experimental Corneal UlcersTopical vs Subconjunctival Therapy. Arch Ophthalmol. 1974;92(4):315-317. doi:10.1001/archopht.1974.01010010325013