A study of the accuracy of lens measures

Authors: Hilton, Owen; Obstfeld, Henri

Source: Ophthalmic and Physiological Optics, Volume 18, Number 3, May 1998 , pp. 299-307(9)

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Abstract:

Summary

The accuracy of 26 aged and three new lens measures was investigated. Instruments were applied to surfaces of known curvature employing the conventional, hand-held method as well as while rigged on an optical bench. In addition, using the latter method, a controlled amount of surface tilt was introduced. A large inter-instrument variation in accuracy was encountered. In general, hand-held lens measures were found to provide equally accurate measurements on convex and concave surfaces, with the exception of the −20 D surface, and inclinations from 0° to 5° did not result in erroneous measurements. Results for inclinations of 15° became unreliable. The different usages of the instrument are discussed.

Document Type: Research article

DOI: http://dx.doi.org/10.1046/j.1475-1313.1998.00331.x

Affiliations: 1: Applied Vision Research Centre, Department of Optometry & Visual Science, City University, 311 Goswell Road, London EC1V 7DD, UK

Publication date: 1998-05-01