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Journal of Biomedical Optics

Shack–Hartmann-based objective straylight assessment of the human eye in an increased scattering angle range
Author(s): Stefan Schramm; Patrick Schikowski; Elena Lerm; André Kaeding; Jens Haueisen; Daniel Baumgarten
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Paper Abstract

Objective measurement of straylight in the human eye with a Shack–Hartmann (SH) wavefront aberrometer is limited in imaging angle. We propose a measurement principle and a point spread function (PSF) reconstruction algorithm to overcome this limitation. In our optical setup, a variable stop replaces the stop conventionally used to suppress reflections and scatter in SH aberrometers. We record images with 21 diameters of the stop. From each SH image, the average intensity of the pupil is computed and normalized. The intensities represent integral values of the PSF. We reconstruct the PSF, which is the derivative of the intensities with respect to the visual angle. A modified Stiles Holladay approximation is fitted to the reconstructed PSF, resulting in a straylight parameter. A proof-of-principle study was carried out on eight healthy young volunteers. Scatter filters were positioned in front of the volunteers’ eyes to simulate straylight. The straylight parameter was compared to the C-Quant measurements and the filter values. The PSF parameter shows strong correlation with the density of the filters and a linear relation to the C-Quant straylight parameter. Our measurement and reconstruction techniques allow for objective straylight analysis of visual angles up to 4 deg.

Paper Details

Date Published: 1 July 2016
PDF: 10 pages
J. Biomed. Opt. 21(7) 076003 doi: 10.1117/1.JBO.21.7.076003
Published in: Journal of Biomedical Optics Volume 21, Issue 7
Show Author Affiliations
Stefan Schramm, Technische Univ. Ilmenau (Germany)
Patrick Schikowski, GMC Systems mbH (Germany)
Elena Lerm, Technische Univ. Ilmenau (Germany)
André Kaeding, GMC Systems mbH (Germany)
Jens Haueisen, Technische Univ. Ilmenau (Germany)
Daniel Baumgarten, Technische Univ. Ilmenau (Austria)

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