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Y. Zhang, M. M. Gabriel, M. Mowrey-McKee, R. P. Barrett, L. D. Hazlett; Rat Silicone Hydrogel Contact Lens Model: Effects of High vs. Low Dk Lens Wear. Invest. Ophthalmol. Vis. Sci. 2008;49(13):832.
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© ARVO (1962-2015); The Authors (2016-present)
This study used a rat contact lens (CL) model to test if high vs. low Dk lens wear caused changes in: 1) conjunctival Langerhans cell (LC) number or location; 2) Bcl-2 (anti-apoptotic) expression; and 3) infection risk.
Female, Lewis rats wore a high or low Dk CL continuously for 2 weeks. Afterward, corneas were harvested and processed for ADPase activity to identify Langerhans cells (n=6/group) for immunostaining (n=3/group) and for real time RT-PCR (n=6/group). CL wearing rats (n=10/group) also were challenged with Pseudomonas aeruginosa by placing a bacterial-soaked CL on the eye followed by topical delivery of bacteria. After 48 hours, slit lamp examination and real time RT-PCR were used to evaluate the corneal response.
Conjunctival LC were significantly increased after low vs. high Dk CL wear (p<0.0001). In contrast, conjunctival LC in non-lens wearing rats was not significantly different from the high Dk lens wearing group. Bcl-2 mRNA levels were significantly decreased in low vs. high Dk CL wearing rats, while Bax, FasL, caspase 3 and caspase 9 levels were unchanged. Immunostaining for Bcl-2 showed fewer positively stained epithelial cells in the low vs. high Dk lens wearing group. After bacterial challenge, 30% of low vs. none of the high Dk CL wearing corneas became infected and showed increased mRNA levels for several pro-inflammatory cytokines/chemokines, inducible nitric oxide synthase (iNOS) and matrix metalloproteinase (MMP)-9.
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