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N. Yamamoto, N. Yamamoto, J.V. Jester, H.D. Cavanagh; Pathophysiological Corneal Epithelium Changes After Prolonged Low–Dk RGP Lens Wear or Eyelid Closure–Induced Hypoxia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):900.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Determine pathophysiological effects of low–Dk RGP CTL–wear or eyelid closure induced–hypoxia on corneal epithelium. Methods: 37 NZW rabbits (15–20 weeks old) were used for this study and treated according to the ARVO statement for the use of animals in ophthalmic and vision research. One randomly chosen eye was fitted with a low–Dk RGP lens (EOP=5.8) or was sutured closed (EOP=7.7) ; the other served as a control. After 72–hour wear or 24, 72, 168 hour of closure, rabbits were humanly sacrificed. Western blots for Bcl–2 were performed (n=4). Epithelial and stromal thickness and surface cell size after 72–hour low–Dk RGP CTL–wear or eyelid closure were measured by in vivo confocal microscopy. To assess the susceptiblity to Pseudomonas aeruginosa ATCC27853 (PA) binding, lipid rafts were stained with ß–cholera toxin with or without bacteria. Results: 24–hour eyelid closure showed no changes of Bcl–2 expression. After 72–hour, Bcl–2 expression decreased in both closed eye and low–Dk CTL–wearing corneal epithelium. At 72–hours, closed eye decreased Bcl–2 expression as much as low–Dk RGP. 72–hour low–Dk RGP CTL–wear and eyelid closure increased stromal thickness (low–Dk RGP CTL : 325.1µm ± 32.7 to 375.2µm ± 41.5 p<0.01, eyelid closure : 319.5µm ± 14.2 to 355.8µm ± 31.8 p<0.05) but with no significant changes in epithelial thickness or surface cell size. 72–hour closed eyes showed many lipid raft forming cells in central corneal epithelium; however, low–Dk RGP CTL–wearing eyes and control eyes showed no lipid raft forming cells centrally but occasionally showed raft formation in the peripheral cornea. ß–cholera toxin staining with PA showed colocalization of PA with those lipid raft forming cells. Conclusions: Bcl–2 expression changes, epithelial or stromal thickness, and sureface cell size indicate identical effects of low–Dk CTL–wear or eyelid closure. However ß–cholera toxin staining suggests low–Dk CTL–wear or eyelid closure increase susceptibility to bacteria in a different manner.
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