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A. Vijay, P. Sankaridurg, M.D. P. Willcox, D.F. Sweeney; Ocular Responses To Contact Lens Wear on an Extended Wear Schedule in a Guinea Pig Model for Lens Wear . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2074.
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Purpose: To develop an animal model for contact lens wear and to determine whether the ocular responses to contact lenses were similar to the responses seen in human eye. Methods: Guinea pigs were divided into 2 groups of 5 animals each and fitted with specially designed soft contact lenses in one eye. Group 1 was fitted with low Dk hydrogel lenses and group 2 was fitted with high Dk hydrogel lenses. Low Dk lenses were worn on a 6 day and night extended wear and disposal schedule and high Dk lenses were worn on a 30 day and night continuous wear schedule. The study was conducted for 3 months and ocular assessments (bulbar and limbal redness, endothelial polymegethism) conducted following 1 night, 1 week, 1 month, 2 months and 3 months of lens wear. Ocular assessments were conducted with slit lamp biomicroscopy and confocal microscopy. Results: Bulbar redness was increased at all the examination time points (p<0.05) in both low and high oxygen permeable lens wearing eyes compared to control eyes; there was a clinical (Grade 2) and statistical increase in the limbal redness response in low Dk lens wearing eyes when compared to control eyes after 3 months of lens wear (p<0.05). There was a significant increase in the co–efficient of variation of endothelial cell size in low Dk lens wearing eyes after just 1 week of lens wear compared to control eyes (p<0.05) and remained elevated through out the period of the study. There were no significant differences in the limbal redness (p>0.5) or the co–efficient of variation of endothelial cell size (p>0.1) between control and high Dk lens wearing eyes. These results are in good agreement with the responses reported in human eyes with extended wear of high and low Dk lenses. Conclusions: Guinea pig ocular responses following extended wear of contact lens are consistent with human ocular responses. The guinea pig is a reliable model that can be used for contact lens extended wear studies.
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