title: Astigmatism at nearpoint: adventitious, purposeful, and environmental influences.
abstract: Previous studies indicate that a number of individuals display significant differences between astigmatism measured at farpoint and nearpoint. Adventitious effects, purposeful lenticular changes and adaptations in response to environmental forces are reviewed as possible sources of this astigmatic variability.
authors.affiliation: School of Optometry, University of Missouri, St. Louis 63121-4499.
authors.forename: S B
authors.initials: SB
authors.lastname: Nicholson
authors.forename: R P
authors.initials: RP
authors.lastname: Garzia
mesh_terms: D000065:Accommodation, Ocular; D001251:Astigmatism / Q000473:pathology / Q000503:physiopathology*; D003315:Cornea / Q000473:pathology / Q000503:physiopathology; D004777:Environment; D005139:Eyeglasses; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology / Q000503:physiopathology; D014836:Volition