Intravitreal toxicity of moxifloxacin.

Objective: 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 microg/0.1 mL, 160 microg/0.1 mL, 100 microg/0.1 mL, and 50 microg/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 microg/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 < or =160 microg/0.1 mL.

Conclusions: Intravitreal injection of moxifloxacin at a concentration of < or =160 microg/0.1 mL appeared nontoxic in the rabbit eye.