Peripheral refraction validity of the Shin-Nippon SRW5000 autorefractor
Osuagwu, Uchechukwu Levi, Suheimat, Marwan, Wolffsohn, James S., & Atchison, David A. (2016) Peripheral refraction validity of the Shin-Nippon SRW5000 autorefractor. Optometry and Vision Science. (In Press)
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Purpose: To investigate the operation of the Shin-Nippon/Grand Seiko autorefractor and whether higher-order aberrations affect its peripheral refraction measurements.
Methods: Information on instrument design, together with parameters and equations used to obtain refraction, was obtained from a patent. A model eye simulating the operating principles was tested with an optical design program. Effects of induced defocus and astigmatism on the retinal image were used to calibrate the model eye to match the patent equations. Coma and trefoil were added to assess their effects on the image. Peripheral refraction of a physical model eye was measured along four visual field meridians with the Shin-Nippon SRW-5000 and a Hartmann-Shack aberrometer, and simulated autorefractor peripheral refraction was derived using the Zernike coefficients from the aberrometer.
Results: In simulation, the autorefractor’s square image was changed in size by defocus, into rectangles or parallelograms by astigmatism, and into irregular shapes by coma and trefoil. In the presence of 1.0 D oblique astigmatism, errors in refraction were proportional to the higher-order aberrations, with up to 0.8 D sphere and 1.5 D cylinder for ±0.6 µm of coma or trefoil coefficients with a 5 mm diameter pupil. For the physical model eye, refraction with the aberrometer was similar in all visual field meridians, but refraction with the autorefractor changed more quickly along one oblique meridian and less quickly along the other oblique meridian, than along the horizontal and vertical meridians. Simulations predicted that higher-order aberrations would affect refraction in oblique meridians, and this was supported by experimental measurements with the physical model eye.
Conclusions: The autorefractor’s peripheral refraction measurements are valid for horizontal and vertical field meridians, but not for oblique field meridians. Similar instruments must be validated before being adopted outside their design scope.
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|Item Type:||Journal Article|
|Keywords:||Peripheral refraction, Shin-Nippon/Grand Seiko autorefractor, COAS-HD, Higher-order aberrations, Hartmann Shack aberrometer|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Optical Technology (111302)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Vision Science (111303)
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Optometry & Vision Science
|Copyright Owner:||Copyright 2016 American Academy of Optometry|
|Copyright Statement:||This is a non-final version of an article published in final form in (provide complete journal citation)|
|Deposited On:||18 Sep 2016 23:22|
|Last Modified:||28 Sep 2016 04:11|
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