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Accuracy and precision of videokeratoscopes for test surfaces

Tang, Wilfred, Collins, Michael J., & Carney, Leo G. (2000) Accuracy and precision of videokeratoscopes for test surfaces. Clinical and Experimental Optometry, 83(2), p. 86.

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: Journal Article
Additional Information: The contents of this journal from 1998 to 2005 can be freely accessed online via the journal's web page (see hypertext link).
Additional URLs:
ISSN: 0816-4622
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: 11 Aug 2011 03:46

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