To determine whether intravitreal dexa methasone administration can alter the elimination of intravitreal vancomycin hydrochloride in rabbit eyes with experimental Streptococcus pneumoniae endophthalmitis. Methods: Albino rabbits were infected with an intravitreal inoculum of S pneumoniae (2 ϫ 10 3 colony-forming units) and randomized after 24 hours to treatment with intravitreal vancomycin hydrochloride (1 mg), alone or in combination with intravitreal dexamethasone (400 µg). For comparison, uninfected eyes were similarly treated. All eyes were enucleated 24, 48, or 72 hours after treatment, and vitreous levels of vancomycin were quantitated using a fluorescence polarizing immunoassay. Results: The half-life of intravitreal vancomycin in infected eyes was prolonged from 48 to 84 hours when eyes were treated with dexamethasone. Conversely, such treatment shortened the half-life in uninfected eyes from 56 to 42 hours. Conclusions: Intravitreal dexamethasone administration reduces the elimination of intravitreal vancomycin in rabbit eyes with pneumococcal endophthalmitis, whereas an opposite effect is noted in uninfected eyes.

• Metastatic breast cancer (BC) to the vitreous is very rare, with only five prior cases confirmed by vitreous biopsy having been reported in the literature. • Metastatic BC to the vitreous can present with clinical and imaging findings mimicking an infectious or inflammatory process. Novel Insights • This report is the first to document heterogenous clumpy material on the retinal surface using spectraldomain optical coherence tomography. • This report is the first to document vasculitis-like findings with modern wide-field retinal photography and fluorescein angiography.