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Accuracy and precision of videokeratoscopes for test surfaces

Tang, Wilfred, Collins, Michael J., & Carney, Leo G. (1999) Accuracy and precision of videokeratoscopes for test surfaces. In 8th Scientific Meeting in Optometry, 1–3 July 1999, The University of New South Wales, Australia.

Abstract

The present study evaluated the accuracy and precision performance of three videokeratoscopes (the Keratron, TMS-1 and PAR systems) in elevation topography with six test surfaces that were designed to challenge each instrument’s ability to measure them. The test surfaces comprised a sphere (r = 7.8 mm), an asphere (r = 7.8 mm, Q = - 0.49), a multicurve (r1 = 7.84 mm, r2 = 7.54, r3 = 7.84, r4 = 7.54, r5 = 7.84), a 5.0 bicurve (r1 = 5.0 mm, r2 = 7.80), a 6.5 bicurve (r1= 6.5 mm, r2 = 7.80) and an 8.5 bicurve (r1= 8.5 mm, r2= 7.80, sag = 50 μm). For the spherical test surface, the root mean square error (RMSE) data showed the instrument accuracies for the Keratron, TMS-1 and PAR systems were 1.64, 2.61 and 20.89 μm, respectively. The standard error for the Keratron system was small (< ± 1 μm) for the same test surface, compared to the standard errors of ± 3 and ± 44 μm for the TMS-1 and PAR systems. Overall, each instrument performed well on certain test surfaces but none of the instruments excelled on all the surfaces. The study has confirmed the high accuracy of the Keratron system in measuring test surfaces such as the sphere, the asphere and the multicurve. The precision of the instrument was the best among the three instruments. The TMS-1 system was slightly less accurate and precise than the Keratron system in elevation topography for the sphere and the asphere surfaces. Of the three instruments, the PAR system has the poorest performance in accuracy and precision.

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ID Code: 12145
Item Type: Conference Paper
Additional Information: Abstract published in Clinical and Experimental Optometry, 83(2), p. 86
Additional URLs:
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Optical Technology (111302)
Divisions: Current > Research Centres > Centre for Health Research
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2000 Optometrists Association Australia
Deposited On: 21 Jan 2008
Last Modified: 03 Nov 2014 14:13

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