title: Changes in the orientation of the axis of astigmatism associated with age.
abstract: A new regression equation for the change in the axis of astigmatism with age, as deduced from cross-sectional studies, is presented. Possible artefacts arising from the methods used to obtain mean prescriptions are discussed; it is shown that these may result in over-estimation of the occurrence of oblique cylinders in middle-age and that a previously demonstrated gradual change of orientation of the axis of astigmatism may have no basis in reality. The need for further longitudinal studies is emphasized.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D001251:Astigmatism / Q000503:physiopathology*; D002648:Child; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological