Retinal toxicity of intravitreal sparfloxacin, ofloxacin, and imipenem in a rabbit model

To determine whether intravitreal sparfloxacin, ofloxacin, and imipenem at varying concentrations cause retinal damage, 50 eyes from 25 rabbits were utilized in the experimental protocol. The rabbits were classified into three groups each containing 15 eyes. Five eyes in each group were given high-, moderate-, or low-dose antibiotic into thevitreous. Group I eyes were injected with sparfloxacin 100 mu g, 50 mu g or 2.5 mu g; group 2: ofloxacin 200 mu g, 100 mu g, or 10 mu g; group 3: imipenem 10 mu g, 5 mu g, or 0.5 mu g. Five control eyes were given intravitreal balanced salt solution. All eyes were examined by indirect ophthalmoscopy before and after intravitreal injections and at 24 h, I week, and 2 weeks after injection. All eyes were enucleated at 2 weeks and fixed for histological evaluation. Except for seven eyes injected with 10 ug or 5 ug imipenem, which demonstrated tracevitreal reaction, no other eyes revealed vitreal inflammation by indirect ophthalmoscopy. By light microscopy, of five eyes injected withsparfloxacin 100 mu g, three had retinal damage but no vitreal inflammation; one had both retinal damage and vitreal inflammation. Of five eyes injected with sparfloxacin 50 mu g, only one was abnormal withboth retinal damage and vitreal inflammation. Of five eyes injected with ofloxacin 200 mu g, one had retinal damage, one had vitreal inflammation, and one had both retinal damage and vitreal inflammation. Of the five eyes injected with ofloxacin 100 mu g, none showed retinaltoxicity but three showed vitreal inflammation. All 10 eyes injectedwith 10 jig or 5 mu g imipenem had mild vitreal inflammation but no retinal damage. None of 15 eyes given sparfloxacin 2.5 jug, ofloxacin10 mu g, or imipenem 0.5 mu g had vitreal inflammation or retinal damage. Eyes given high or moderate doses of any study antibiotic that showed no inflammation or retinal damage by light microscopy were randomly selected for transmission electron microscopy (TEM), which documented [ABSTRACT FROM AUTHOR]