Considerations in Contact Lens Use Under Adverse Conditions Proceedings of a Symposium (1991) / Chapter Skim
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Contact Lenses and Corneal Energy Metabolites in the Rabbit
Contact Lenses and Corneal Energy Metabolites in the Rabbit
Pages 24-33
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From page 24... ...
A new study will attempt to examine the third issue of physiological/biochemical effects of contact lens wear in an animal model. The remainder of this discussion will highlight four issues concerning contact lens wear, summarize the methodology being used by this investigator, and provide normative energy metabolite data for the corneal epithelium of the pigmented rabbit.
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From page 25... ...
It has been suggested that contact lenses may cause a delay in epithelial cell turnover characterized by the presence of abnormal, large, senescent surface cells (Lemp and Gold, 1986~; other findings included trapped surface debris, intraepithelial pseudocysts, and increased uptake of water-soluble dyes, suggesting increased permeability of these surface cells. An additional issue has surfaced in the past 2 years: carbon dioxide expiration.
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From page 26... ...
Continuing along that line of thought, the typical corneal endothelial mosaic, consisting of cells of similar shape and size, may be altered by contact lens wear such that the normally uniform monolayer is transformed into a variety of cell shapes (pleomorphism) and a variety of cell sizes (polymegethism)
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From page 27... ...
The animals are maintained and the experiments conducted in accordance with procedures outlined in the Guide for Laboratory Animals Facilities and Care of the National Research Council (1965~. Appropriately sized contact lenses are worn on one eye only for a predetermined period of time.
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From page 28... ...
The different layers of the cornea are clearly defined, which permits easy isolation of the corneal epithelium under a 3x binocular dissecting microscope. Tissue size is determined by dry weight, rather than by tissue section dimensions, which permits the analysis of very small and irregularly shaped specimens.
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From page 29... ...
Although free glucose is suggested to be present in adequate amounts to sustain purely anaerobic activity (Riley, 1969) , studies have shown glycogen mobilization to be quite responsive in times of stress (Uniacke and Hill, 1972; Thoft and Friend,1975~.
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From page 30... ...
Prior researchers have inferred, because of a decreased oxygen availability during contact lens wear, that glycogen depletion represents an increase in epithelial glucose consumption as a result of glycolyiic compensation. However, if stromal pH changes reflect actual epichelial intracellular conditions, then the glycogen depletion may represent merely decreased activity in the enzyme system responsible for glycogen synthesis or, on the other hand, increased activity in the enzyme system responsible for glycogen degradation.
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From page 31... ...
Lemp, M.A., and J.B. Gold 1986 The effects of extended wear hydrophilia contact lenses on the human corneal epithelium.
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1982 Corneal thickness and endothelial cell changes associated with daily and extended contact lens wear. Master's thesis, Ohio State University.
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From page 33... ...
Holden 1977 Transient endothelial cell changes soon after wearing soft contact lenses. American Journal of Optometry and Physiological Optics 54:856-861.
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