Collagen shields and intraocular drug delivery: concentration of gentamicin in the aqueous and vitreous of a rabbit eye after lensectomy and vitrectomy.

Five albino New Zealand rabbits underwent bilateral lensectomy and vitrectomy. All left eyes were fitted with a collagen shield that had been soaked for 5 min in 2.0 mL of gentamicin solution (40 mg/mL for IV use). Right eyes were treated with fortified gentamicin drops (13.6 mg/mL) every 30 min for 12 hrs. Aqueous and vitreous specimens were obtained at the following time intervals: 1, 2, 4, 8, 12 and 24 hrs. We found the gentamicin concentrations to be higher in the aqueous of all eyes treated with fortified gentamicin drops. Only those eyes treated with fortified gentamicin drops attained a therapeutic drug level (4 micrograms-9 micrograms/mL) in the aqueous. Therapeutic drug levels were not attained in the vitreous of either treatment group.