Abstract
Abstract: :
Purpose: To assess the retinal toxicity of varying concentrations of intravitreally injected gatifloxacin and levofloxacin. Methods: Twenty New Zealand albino rabbits were used for this study (1 eye each). The animals were anesthetized and treated according to the ARVO resolution. Gatifloxacin in an initial concentration of 2 mg/ml was titrated using 5% dextrose solution to the following concentrations: 400 µg/ 0.2 ml, 200 µg/0.1 ml, 100 µg/ 0.1 ml, and 50 µg/0.1 ml. Each of these concentrations was injected intravitreally into 2 rabbit eyes. Two eyes were used as control and received 0.1ml of 5% dextrose solution. Levofloxacin in an initial concentration of 25 mg/ml was titrated using 5% dextrose solution to the following concentrations: 2500 µg/ 0.1 ml, 1250 µg/0.1 ml, 625 µg/ 0.1 ml, 312.5 µg/0.1 ml, and 156 µg/0.1 ml. Each concentration was injected intravitreally into 2 rabbit eyes. The injections were made through the pars plana using a 25–gauge needle positioned behind the lens. An anterior chamber paracentesis was performed to reduce the intraocular pressure. All animals were examined before and after injection using the indirect ophthalmoscope and slit–lamp biomicroscopy. Baseline and postinjection electroretinography were performed. The animals were followed up to 14 days postinjection before being euthanized. The enucleated eyes were examined with light microscopy. Results: ERG changes were considered significant if the follow–up differences in amplitude were decreased greater than 25%. The levofloxacin group exhibited significant decreases in ERG in the eyes injected with 1250 µg and 2500 µg. No retinal toxicity was observed in any of the gatifloxacin–injected eyes. Conclusions: Levofloxacin injected intravitreally appeared safe at concentrations of less than 625 µg. In addition, gatifloxacin injected intravitreally appeared safe at concentrations of 400 µg or less.
Keywords: endophthalmitis • drug toxicity/drug effects • antibiotics/antifungals/antiparasitics