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 (4g–9g/mL) in the aqueous. Therapeutic drug levels were not attained in the vitreous of either treatment group.