W F Harris1. 1. Optometric Science Research Group, Department of Optometry, University of Johannesburg, Johannesburg, South Africa. wfh@na.rau.ac.za
Abstract
PURPOSE: The purpose of this study is to derive the equation for the effect of tilt on the tilted power vector of a possibly astigmatic thin lens. METHODS: The analysis makes use of the equation for tilted power in terms of the dioptric power matrix. RESULTS: A simple equation is obtained for the tilted power vector of a thin lens in terms of the untilted power vector of the lens. A solution of the equation provides a means for compensating spectacle lenses for tilt. Numerical examples are presented in the (available online at www.optvissci.com). CONCLUSIONS: The equation gives insight and is useful for researchers and clinicians working in terms of power expressed as power vectors.
PURPOSE: The purpose of this study is to derive the equation for the effect of tilt on the tilted power vector of a possibly astigmatic thin lens. METHODS: The analysis makes use of the equation for tilted power in terms of the dioptric power matrix. RESULTS: A simple equation is obtained for the tilted power vector of a thin lens in terms of the untilted power vector of the lens. A solution of the equation provides a means for compensating spectacle lenses for tilt. Numerical examples are presented in the (available online at www.optvissci.com). CONCLUSIONS: The equation gives insight and is useful for researchers and clinicians working in terms of power expressed as power vectors.