title: Hydrogel contact lens dehydration rates determined by thermogravimetric analysis.
abstract: Because many practitioners believe that the on-eye drying of contact lenses is a source of patient discomfort, we examined the relative dehydration rates of a variety of hydrogel contact lenses. Lens dehydration rates were determined by thermogravimetric analysis at 35[degrees]C. Using the FDA classification scheme for hydrogel lenses, we found that dehydration rates were as follows: group 4 greater than group 2 greater than group 3 greater than group 1. Within groups there was considerable variability in the rates at which lenses dehydrated. For lenses of the same type, we found a near-linear relationship between increasing lens power (which is closely related to center thickness) and decreasing rates of dehydration.
authors.affiliation: Wesley-Jessen Corporation, Chicago, IL.
authors.forename: D O
authors.initials: DO
authors.lastname: Helton
authors.forename: L S
authors.initials: LS
authors.lastname: Watson
mesh_terms: D003263:Contact Lenses, Hydrophilic; D003890:Desiccation; D004209:Disposable Equipment; D055095:Optics and Photonics; D011108:Polymers; D015203:Reproducibility of Results; D013696:Temperature; D013818:Thermogravimetry; D013997:Time Factors
chemical_list: D011108:Polymers