Shack–Hartmann-based objective straylight assessment of the human eye in an increased scattering angle range

Stefan Schramm; Patrick Schikowski; Elena Lerm; André Kaeding; Jens Haueisen; Daniel Baumgarten

doi:10.1117/1.JBO.21.7.076003

1 July 2016 Shack–Hartmann-based objective straylight assessment of the human eye in an increased scattering angle range

Stefan Schramm, Patrick Schikowski, Elena Lerm, André Kaeding, Jens Haueisen, Daniel Baumgarten

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Journal of Biomedical Optics, Vol. 21, Issue 7, 076003 (July 2016). https://doi.org/10.1117/1.JBO.21.7.076003

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.

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Stefan Schramm, Patrick Schikowski, Elena Lerm, André Kaeding, Jens Haueisen, and Daniel Baumgarten "Shack–Hartmann-based objective straylight assessment of the human eye in an increased scattering angle range," Journal of Biomedical Optics 21(7), 076003 (1 July 2016). https://doi.org/10.1117/1.JBO.21.7.076003

Published: 1 July 2016

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