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2004 OMIG, Abstract 13

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Assessment of Corneal Toxicity Following Exposure to VigamoxTM or ZymarTM Using In Vivo Confocal Microscopy and ZO-1 Staining
W M Petroll, HD Cavanagh, JV Jester. Department of Ophthalmology, University of Texas Southwestern, Dallas, Texas

Purpose: To determine the effects of short-term exposure to Vigamox and Zymar on the corneal epithelial surface.
Methods: Studies were performed on 28 New Zealand White rabbits. In vivo confocal microscopy was used to assess epithelial morphology in 18 rabbits. Baseline confocal exams were performed on one eye of each animal. Two weeks later, the eye was bathed with either Vigamox (n = 6) or Zymar (n = 6) for 3 minutes and rinsed with BSS; BSS rinsing without antibiotic treatment was used as a control (n = 6). Immediately following treatment, corneas were examined using in vivo confocal microscopy. ZO-1 labeling was used to assess the integrity of the tight junctions between superficial epithelial cells in 10 rabbits. One eye of each rabbit was bathed with either Vigamox (n = 5) or Zymar (n = 5) for 3 minutes and rinsed with BSS; the contralateral aye served as a control (BSS rinse only). Animals were immediately sacrificed, and corneas were fixed and stained using rat monoclonal anti-ZO-1. Buttons were imaged using laser confocal microscopy.
Results: In Vivo Confocal Microscopy: In the control and Vigamox groups, superficial epithelial cells appeared similar to baseline images, as indicated by their visible cell borders and bright nuclei. In contrast, the surface cells in eyes treated with Zymar appeared smaller, brighter, and had less distinct borders. Quantitative analysis demonstrated a significant decrease in epithelial cell area after treatment with Zymar (p<0.05, Two Way Repeated Measures ANOVA), but not Vigamox or control. This decrease in cell size suggests a loss of some superficial epithelial cells, which leads to exposure of the smaller wing cells on the ocular surface. ZO-1 Labeling: ZO-1 was organized into a continuous linear pattern along the cell-cell junctions in both the control and Vigamox groups. In contrast, ZO-1 staining in eyes treated with Zymar showed regions of dropout, suggesting a loss of superficial calls. Although other regions showed ZO-1 staining along coil junctions, labeling was generally weaker than in the control and Vigamox groups.
Conclusions: Overall, the data demonstrate that following short term exposure to Vigamox, corneal epithelial integrity and tight junction organization are maintained. In contrast, Zymar induces damage to the corneal epithelium in this model, as indicated by a quantitative decrease in surface cell size and loss of normal ZO-1 staining.

Supported by Research to Prevent Blindness and Alcon Laboratories.


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