Intracameral Vigamox (moxifloxacin 0.5%) is non-toxic and effective in preventing endophthalmitis in a rabbit model.

PURPOSE: To determine whether Vigamox (moxifloxacin 0.5% ophthalmic solution) can be safely injected intracamerally to prevent Staphylococcus aureus endophthalmitis in a rabbit model.
DESIGN: Animal study.
METHODS: The safety and bactericidal-effectiveness of Vigamox were evaluated in three stages using 189 New Zealand White rabbits. (Stage 1) The toxicity of two intravitreal doses of Vigamox (moxifloxacin 500, 250 microg) was compared with vancomycin (1 mg) and saline. (Stage 2) A reproducible rabbit model of Staphylococcus aureus endophthalmitis was established. (Stage 3) The bactericidal effect of intracameral Vigamox (moxifloxacin 500, 250, 125, 50 microg) was compared with vancomycin (1 mg) and saline. Intracameral antibiotic therapy commenced immediately after Staphylococcus aureus intravitreal challenge (5000 cfu). Toxicity was evaluated by masked clinical examination using a slit-lamp, an indirect ophthalmoscope, and corneal-ultrasound pachymetry. The clinical examination included the exterior eye, cornea, anterior chamber, vitreous, and retina. The presentations were graded on a severity scale of 0, 0.5, 1, 2, and 3. The bactericidal efficacy was determined using intracameral colony counts.
RESULTS: In the toxicity studies without bacterial challenge, the clinical scores of rabbits injected intracamerally with Vigamox were statistically equivalent to rabbits given intracameral vancomycin or saline. In the efficacy studies, eyes treated intravitreally with Vigamox, at all doses, or vancomycin were negative for Staphylococcus aureus and nontreated controls remained culture-positive.
CONCLUSIONS: Vigamox appears to be nontoxic for intracameral injection and effective in preventing experimental endophthalmitis in the rabbit model. Further studies will determine the clinical role of intracameral Vigamox for surgical prophylaxis and postoperative therapy.