title: Corneal response to different oxygen levels during extended wear.
abstract: In this study we explored the relationship between hypoxic exposure level and corneal response by assuming that the partial pressure of oxygen (PO2) under a contact lens during eye closure is directly related to oxygen transmissibility (Dk/L). To study this relationship, we monitored a group of subjects who wore RGP lenses of various Dk/L values on an extended wear basis. The results revealed that as Dk/L increases, there is a substantial decrease in overnight corneal edema and epithelial microcysts. However, other responses seemingly related to purely mechanical properties (e.g., lens adherence, corneal topographical changes, and 3-9 limbal superficial punctate keratitis) appear to be independent of Dk/L. Results also suggest that sufficient PO2 levels under a contact lens can minimize endothelial morphological changes associated with hypoxia. We conclude that metabolically driven complications accompanying RGP extended wear can be substantially eliminated with lenses having Dk/L values of 80 x 10(-9) (cm x mL O2)/(sec x mL x mm Hg) or greater.
authors.affiliation: Morton D. Sarver Laboratory for Contact Lens and Corneal Research, School of Optometry, University of California, Berkeley 94720.
authors.forename: R K
authors.initials: RK
authors.lastname: Rivera
authors.forename: K A
authors.initials: KA
authors.lastname: Polse
mesh_terms: D000328:Adult; D003262:Contact Lenses, Extended-Wear; D003315:Cornea / Q000378:metabolism* / Q000473:pathology; D015715:Corneal Edema / Q000209:etiology; D003560:Cysts / Q000209:etiology; D004728:Endothelium, Corneal / Q000473:pathology; D006801:Humans; D007634:Keratitis / Q000209:etiology; D008875:Middle Aged; D010101:Oxygen Consumption