The effect of videokeratoscope faceplate design on radius of curvature maps

Monteiro, P.M.L. & Hull, C.C. (2007). The effect of videokeratoscope faceplate design on radius of curvature maps. OPHTHALMIC AND PHYSIOLOGICAL OPTICS, 27(1), pp. 76-84. doi: 10.1111/j.1475-1313.2006.00426.x

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Abstract

A computer model using finite ray tracing methods was developed to simulate a videokeratoscope analysing an average cornea. Different faceplate designs were tested using five points in the faceplate subtending angles between 15 and 75 in 15 intervals at the corneal vertex. Image quality was assessed by adding the geometrical blurs of the 5 image points. Differences (error) between accurate sagittal radius of curvature and sagittal radius of curvature calculated by the van Saarloos algorithm were calculated for selected surfaces at the same corneal points. The calculations were repeated for the tangential radius of curvature. Differences equal or bigger than 0.02 mm were regarded as clinically significant. The surface that provided the sharpest image for an average cornea was a cylinder with the base 120 mm away from the corneal vertex and a diameter of 26 mm. Changing the faceplate design results in clinically significant differences for an average cornea.

Item Type: Article
Uncontrolled Keywords: Videokeratoscopy; Corneal topography; Faceplate design; Radius of curvature maps
Subjects: R Medicine > R Medicine (General)
Divisions: School of Health Sciences > Department of Optometry & Visual Science
URI: http://openaccess.city.ac.uk/id/eprint/5144

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