Intravitreal VigamoxTM (0.5% Moxifloxacin) Is Non–Toxic and Effective in Preventing Endophthalmitis in a NZW Rabbit Model

Abstract

Abstract: : Purpose: To determine whether Vigamox^TM (0.5% moxifloxacin, Alcon Laboratories, Ft. Worth, TX) can be safely injected intravitreally to prevent Staphylococcus aureus endophthalmitis. Methods:The safety and bactericidal effectiveness of Vigamox^TM was evaluated in three experiments using 186 NZW rabbits. 1) A reproducible rabbit model of Staphylococcus aureus endophthalmitis was established. 2) The toxicity of four intravitreal doses of Vigamox^TM (moxifloxacin 500, 250, 125, 50 µg) was compared to vancomycin (1 mg) and saline. 3) The bactericidal effect of Vigamox^TM (moxifloxacin 500, 250, 125, 50 µg) was compared to vancomycin (1 mg) and saline using an one–eye design. The Staphylococcus aureus intravitreal inoculum necessary to reproduce endophthalmitis was 5 x 10³ CFU. Intravitreal therapy commenced immediately after bacterial intravitreal challenge. The safety was evaluated with clinical examination using a slit lamp and an indirect opthalmoscope. 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 effectiveness was determined using colony counts of the vitreous 24 hours after intravitreal therapy. All data were analyzed parametrically using ANOVA with significance set at p=0.05. Results: The total clinical scores of rabbits injected intravitreally with Vigamox^TM, at all doses, were statistically equivalent to rabbits given intravitreal vanocmycin or saline. The vitreous of all eyes treated with Vigamox^TM, at all doses, and vancomycin were negative for Staphylococcus aureus, and the colony counts were 6 logs lower than the non–treated (control) group and 3 logs lower than the initial inoculum. Conclusions: Vigamox^TM appears to be safe for injection into the vitreous to prevent experimental endophthalmitis. Further clinical studies will determine the role of intravitreal Vigamox^TM for surgical prophylaxis and post–operative therapy.

Keywords: endophthalmitis • antibiotics/antifungals/antiparasitics • Staphylococcus