Collagen shield delivery of tobramycin to the human eye

The purpose of this study was to determine the ocular penetration of tobramycin into the anterior chamber of the human eye when delivered by a pre-soaked collagen shield.

We conducted a prospective, randomized study of 32 patients undergoing cataract surgery. The subjects were divided into two groups. The first group received three preoperative drops of commercially available combination tobramycin-dexamethasone drops at 15 minute intervals. In the second group, a collagen shield soaked in the same medication was applied to the eye prior to surgery. At the beginning of surgery, the aqueous humor was extracted for analysis.

The samples from 11 patients could not be analyzed due to an insufficient aqueous sample. Of the remaining 21 patients, the mean aqueous concentration was 0.026 microgram/mL (range: 0.0-0.09) in the drops group and 0.024 microgram/mL (range: 0.04-0.8 microgram/mL) in the shield group. This difference was not statistically significant. The aqueous concentration in both groups did not approach the minimum inhibitory concentration (4 micrograms/mL) for common ocular pathogens. No adverse effects related to the use of collagen shields occurred.

Perioperative use of a pre-soaked collagen shield utilizing a commercially available preparation of tobramycin-dexamethasone combination drops appears safe. However, the use of this system to prevent endophthalmitis is not warranted based on the concentrations obtained from the aqueous humor.