The Effect of a Collagen Shield on Concentrations of Tobramycin in Corneas

ABSTRACT

Collagen shields made of porcine scleral collagen were immersed in a solution containing tobramycin sulfate(40 mg/ml) for five minutes, then applied to rabbit corneas. One, four and eight hours after application, the corneas were assayed for antibiotics by agar diffusion bioassay. We divided study groups as 4 groups, that is, collagen shield, subconjunctival, therapeutic soft contact lens and topical group, and compared the corneal concentradon of tobramycin in each group. Shields immersed in 40 mg/ml tobramycin produced significantly higher concentrations of tobramycin in the cornea at one and four hours than those of the other groups. Tobramycin concentrations in cornea eight hours after application became lower than those of one and four hours after application but, higher than minimal inhibitory concentration of Pseudomonas aeruginosa. Collagen shield containing antibiotics can serve as a vehicle for drug delivery and may prove superior to current methods for the initial treatment of bacterial keratitis, and preoperative and postoperative antibiotic prophylaxis.