Calibration of the Canon R-1 autorefractor for continuous measurement of accommodation
Collins, Michael J., Davis, Brett A., & Atchison, David A. (1992) Calibration of the Canon R-1 autorefractor for continuous measurement of accommodation. In American Academy of Optometry Meeting, 1992, Orlando, Florida.
The Canon Autoref R-1 is an infrared optometer, which allows free-space viewing. Pugh and Winn have described hardware modifications necessary to con vert the Autoref R-1 from an instrument capable of taking single static measurements of the eye's accommodative (refractive) status to an instrument capable of continuous measurement of the accommodative status of the eye. We describe two methods of calibrating the Autoref R-1 for continuous measurement of accommodation for any individual eye. In the first method we establish the relationship between accommodation stimulus/response and the voltage output of the Autoref R-1. In the second method we calibrate the voltage output of the Autoref R-1 with the position of the internal focusing lens system ( wave form) in reference to the stimulus/response relationship. The assumptions and sources of error underlying these calibration techniques are discussed. We present data on the accuracy of the calibration of the Autoref R-1 for continuous measurements, by comparing repeated static and continuous readings taken under identical stimulus conditions. The differences between static and continuous readings are small (<0.25D). To determine the accuracy of the static shot measures, five cyclopleged subjects wore a range of soft lenses with powers ranging from -3 to +6D. The regression on these data gave y=0.11+0.99x, r=0.98, indicating a high level of reliability. A further subject wore opaque tinted soft contact lenses with clear pupil diameters of 3, 4, 5, 6 and 8mm. The continuous Autoref R-1 output signal is influenced for pupil sizes of less than 4mm.
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|Item Type:||Conference Paper|
|Additional Information:||abstract published in Optometry and Vision Science, 96, pp.111|
|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
|Deposited On:||25 Jan 2008|
|Last Modified:||10 Nov 2014 03:00|
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