Intravitreal Toxicity of Moxifloxacin

In Brief Purpose: To assess the retinal toxicity of various concentrations of intravitreally administered moxifloxacin, a fourth-generation fluoroquinolone. Methods: Ten New Zealand albino rabbits were divided into five groups. The initial concentration of moxifloxacin (400 mg/250 mL) was titrated using 5% dextrose solution to concentrations (320 μg/0.1 mL, 160 μg/0.1 mL, 100 μg/0.1 mL, and 50 μg/0.1 mL) that were injected intravitreally into 1 eye of each rabbit. Two control eyes were injected intravitreally with 0.1 mL of 5% dextrose solution. All animals were examined before and after injection by indirect ophthalmoscopy and slit-lamp biomicroscopy; electroretinography (ERG) was performed on all animals. The animals were killed, and their eyes were enucleated and examined with light microscopy. Results: Remarkable decreases in ERG findings were noted in the group injected with moxifloxacin at a concentration of 320 μg/0.1 mL. No meaningful ERG changes were observed in eyes injected with moxifloxacin at other concentrations. There were no signs of retinal toxicity during slit-lamp examination, indirect ophthalmoscopy, or light microscopy in any eyes injected with moxifloxacin concentrations of ≤160 μg/0.1 mL. Conclusions: Intravitreal injection of moxifloxacin at a concentration of ≤160 μg/0.1 mL appeared nontoxic in the rabbit eye. The intravitreal toxicity of moxifloxacin, a fourth-generation fluoroquinolone, was evaluated in rabbit eyes using electroretinography and light microscopy. Eyes treated with doses of moxifloxacin at concentrations of ≤160 μg/0.1 mL had no evidence of intravitreal toxicity. Moxifloxacin requires further evaluation as a potential treatment of endophthalmitis.