Retinal Toxicity of Intravitreal Sparfloxacin, Ofloxacin, and Imipenem in a Rabbit Model

• Published in: Journal of toxicology. Cutaneous and ocular toxicology 1999-01, Vol.18 (1), p.65-73
• Main Authors: Miriam, A. Smith, D'Aversa, Gerard, Sable, Michael, Farbowitz, Michael, Sorenson, John, Green, W. Richard
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Drug toxicity and drugs side effects treatment; Medical sciences; Pharmacology. Drug treatments; Toxicity: eye
• ISSN: 0731-3829; 1532-2505
• DOI: 10.3109/15569529909049324

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 the vitreous. Group 1 eyes were injected with sparfloxacin 100 μg, 50 μg or 2.5 μg; group 2: ofloxacin 200 μg, 100 μg, or 10 μg; group 3: imipenem 10 μg, 5 μg, or 0.5 μg. 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, 1 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 μg or 5 μg imipenem, which demonstrated trace vitreal reaction, no other eyes revealed vitreal inflammation by indirect ophthalmoscopy. By light microscopy, of five eyes injected with sparfloxacin 100 μg, three had retinal damage but no vitreal inflammation; one had both retinal damage and vitreal inflammation. Of five eyes injected with sparfloxacin 50 μg, only one was abnormal with both retinal damage and vitreal inflammation. Of five eyes injected with ofloxacin 200 μg, 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 μg, none showed retinal toxicity but three showed vitreal inflammation. All 10 eyes injected with 10 μg or 5 μg imipenem had mild vitreal inflammation but no retinal damage. None of 15 eyes given sparfloxacin 2.5 μg, ofloxacin 10 μg, or imipenem 0.5 μg 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 retinal toxicity. In addition, TEM confirmed the absence of retinal damage in all 15 eyes given the low dose of intravitreal antibiotics. Intravitreal injection of low-dose sparfloxacin, ofloxacin, and imipenem is nontoxic to the retina. TEM should be done in eyes that are normal by light microscopy to determine whether retinal toxicity is present.