title: A unifying parameter to describe the clinical mechanics of hydrogel contact lenses.
abstract: We studied the relation of postlens squeeze pressure to the clinical fit of hydrogel contact lenses. This relation was statistically significant (p less than 0.01) for a variety of contact lenses currently prescribed over a range of thickness, water content, back central optic radius, diameter, and back vertex power. The squeeze pressure provided a useful parameter to describe and compare the clinical fit of hydrogel contact lenses and a model with which the fit of a lens to an eye could be predicted. There was virtually no movement of the contact lenses across the eye when the squeeze pressure was more than -14 mm H2O (-1370 dynes/cm2). However, the mechanics of the lens motion when the squeeze pressure was less than this critical pressure appeared to be related to a more complicated combination of the squeeze pressure and the other forces in the eye-lens system.
authors.affiliation: School of Optometry, University of New South Wales, Kensington, Australia.
authors.forename: D K
authors.initials: DK
authors.lastname: Martin
authors.forename: J
authors.initials: J
authors.lastname: Boulos
authors.forename: J
authors.initials: J
authors.lastname: Gan
authors.forename: K
authors.initials: K
authors.lastname: Gavriel
authors.forename: P
authors.initials: P
authors.lastname: Harvey
mesh_terms: D003263:Contact Lenses, Hydrophilic; D003315:Cornea / Q000033:anatomy & histology; D006801:Humans; D011312:Pressure; D013666:Tears / Q000032:analysis