Effect of intravitreal injection of norfloxacin on the retina in pigmented rabbits.

The effect of an intravitreal injection of norfloxacin on the retina was evaluated by in-vivo electroretinogram (ERG) and histological examination in pigmented rabbits. The intraocular pharmacokinetics after an intravitreal injection of norfloxacin were also investigated. An intravitreal injection of 50 micrograms norfloxacin produced no significant change in the ERG. An injection of 500 micrograms norfloxacin decreased the amplitude of the oscillatory potentials, and delayed their peak latencies 3 hours after the injection, but these changes recovered within 7 days. A marked suppression of the c-wave was noted in one pigmented rabbit. Neither 50 micrograms nor 500 micrograms norfloxacin caused any apparent changes in the visual evoked potential and in the retinal histology 7 days after the injection. The intraocular pharmacokinetic study showed that the concentration of norfloxacin in the choroid-retina was almost the same level as that in the vitreous body 3 hours after the injection. However, the former was higher than the latter 7 days after the injection, suggesting the persistency of norfloxacin in the choroid-retina. An intravitreal injection of 50 micrograms norfloxacin could be used without retinal toxicity. A high dose-intravitreal use of norfloxacin needs careful attention with respects to its persistency in the pigmented ocular tissues.