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D-UG Bartsch, WR Freeman; Characterization of Whole Eye Aberration by Laser Ray Tracing and Hartmann-Shack Wavefront Sensing . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2055.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To compare the capabilities of a commercially available laser ray tracing instrument to a Hartmann-Shack sensor for characterizing whole eye aberrations. Additionally, we measured the reproducibility of both instruments in a clinical setting. Methods:We used a Tracey Visual Function Analyzer (VFA, Tracey Technologies, Houston, TX) and a Hartmann-Shack wavefront sensor (Flexible Optical B.V., Delft, The Netherlands) to measure the wavefront in 10 normal volunteers. The VFA uses a red laser diode for illumination and the Hartmann-Shack wavefront sensor uses a near-infrared laser light source. Results:The VFA is a single-beam scanning refractometer based on retina ray tracing. The instrument measures 64 points of the retina and optical system of the eye by sampling each thin beam 5 times through the pupil in less than 500 milliseconds. The VFA allows rapid characterization of the refractive error and calculation of the point spread function. The instrument also allows to quantify the accommodation range of the eye with a built-in adjustable fixation target. The VFA has a reproducibility of RMS measurements of 10%. The Hartmann-Shack wavefront sensor allows wavefront profile measurement with a RMS sensitivity of λ/40 in visible light imaging. Conclusion:Both instruments allow wavefront characterization. The VFA allows very rapid acquisition of the image. In clinical examination, the Hartmann-Shack wavefront sensor typically uses 5 images and discards the two worst images. This may make use of this instrument for adaptive less suitable than a ray tracing approach.
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