The aim of this study was to investigate the efficacy of intravitreal
povidone-iodine (PI) in the treatment of
vancomycin-resistant Enterococcus faecalis (VRE)
endophthalmitis. Fifty New Zealand white rabbits were divided into 5 groups (n = 10 in each group). After the induction of
endophthalmitis using VRE (minimum inhibitory concentration [MIC] ≥ 40 μg/mL) in the right eye, Group A, B, C, and D received
intravitreal injections of 0.1% PI, 0.3% PI, 0.05%
vancomycin, and 0.5%
vancomycin, respectively. Eyes in Group E were used as controls. Fundus photography, vitreous culture, electroretinography (ERG), and histologic examinations of the retina were conducted on day 14. A marked improvement in
endophthalmitis was observed in Group A, B, C and D, compared to Group E. Fundus photographs showed mild vitreous opacities in Group A and B, and moderate vitreous opacity in Group C. All eyes in Group D had a clear vitreous. In vitreous culture, bacterial growth was found in 6 eyes (100, 200, 200, 400, 500, and 500 colony-forming units) in Group C, but not in Groups A, B, or D. ERG and histological examination also indicated intraocular damage in Group C. Our results show that
intravitreal injection of PI, even at low concentrations, was effective for treatment of VRE
endophthalmitis, although some vitreous opacity remained. Intravitreal
vancomycin injection was also useful to treat resistant strains, if used at a higher concentration within the safety threshold.