Abstract
Abstract: :
Purpose: To measure non–invasively the rabbit corneal epithelial permeability following exposure to 4th generation fluoroquinolone antibiotic solutions. Methods: The unanesthetized rabbit’s lower eyelid was extended so that the corneal surface could be bathed in vivo for 3 minutes with BSS®, VigamoxTM, or ZymarTM. Visine® Original was used as a positive control. Following a 5–ml flush with BSS®, the corneal surface was bathed in 0.075% sodium fluorescein for 3 minutes. Afterwards, corneal epithelial cell uptake of fluorescein was assessed with the slit lamp and a fluorophotometer (OcuMetrics, CA). The fluorophotometer was used to determine epithelial cell layer permeability. The corneal tissue was also prepared for scanning and transmission electron microscopy. Results: There were four randomized groups (1) OS treated with VigamoxTM and OD treated with BSS®, n=20 rabbits, (2) OS treated with ZymarTM and OD treated with BSS®, n=20 rabbits, (3) OS treated with VigamoxTM and OD treated with ZymarTM, n=20 rabbits, and (4) treated with Visine®, n=6 eyes. The BSS® was used as a control solution. The corneal epithelial cell layer permeability to sodium fluorescein following exposure to BSS® was 0.54 ± 0.21 nm/sec, to VigamoxTM was 0.55 ± 0.19 nm/sec, to ZymarTM was 6.07 ± 2.13 nm/sec, and to Visine® was 17.69 ± 2.73 nm/sec. Paired t–tests of groups (1), (2) and (3) were performed. In rabbits treated with BSS® and VigamoxTM the paired t–test had a p=0.80. In rabbits treated with BSS® and ZymarTM the paired t–test had a p<0.0001. In rabbits treated with ZymarTM and VigamoxTM the paired t–test had a p<0.0001. The microscopy provides supportive data to the permeability alterations from control. Conclusions:The epithelial permeabilities of corneas exposed to either BSS® or VigamoxTM were statistically equivalent. By comparison, the epithelial permeabilities of corneas exposed to either BSS® or VigamoxTM were statistically different from ZymarTM. ZymarTM caused a decrease in the epithelial cell layer barrier – an 11–fold increase in epithelial permeability as compared to VigamoxTM. The changes in permeability correlate with the amounts of preservative in these products: Visine® contains 0.01% benzalkonium chloride, ZymarTM contains 0.005% benzalkonium chloride; whereas, BSS® and VigamoxTM do not contain benzalkonium chloride.
Keywords: antibiotics/antifungals/antiparasitics • cornea: epithelium • microscopy: light/fluorescence/immunohistochemistry