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Proceedings Paper

SLO saccade profile measurements and the effects of retinal raster size and distortion
Author(s): Martin Stetter; George T. Timberlake; R. A. Sendtner; Robert H. Webb
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Paper Abstract

We present a high resolution, noninvasive method for measuring saccade profiles based on retinal images obtained with the scanning laser ophthalmoscope (SLO) and investigate the effect of SLO raster distortion on saccade measurements. The method uses the fact that images of horizontally moving objects made with the SLO show a systematic distortion: images of vertical edges show a tilt towards the horizontal. First, a mathematical framework is given for the quantitative determination of instantaneous saccade velocities from this tilt. Under the assumption that the SLO provides undistorted retinal images, it is shown that saccade profiles can be obtained in a simple way from a restricted number of successive digitized SLO video fields, which are calibrated with respect to the visual angle they cover. Second, SLO raster (and image) distortions that could affect saccade measurement are examined theoretically and by numerical methods. We show that for emmetropic eyes the retinal raster shape and size are virtually unaffected by changes in the axial and lateral positions of the beam-scan waist. Image distortions due to distortions of the SLO raster and due to the optical properties of the eye are found to be present but can be corrected by applying an empirically determined inverse distortion transform. The method is applied to sequences of successive digitized fundus images taken with a Rodenstock SLO. Measurements of retinal blood vessel tilts during saccades from these video fields were used to determine saccade profiles. Shapes of the saccade profiles measured using our method agree well with results obtained by others using different eye movement recording techniques.

Paper Details

Date Published: 10 January 1996
PDF: 12 pages
Proc. SPIE 2632, Lasers in Ophthalmology III, (10 January 1996);
Show Author Affiliations
Martin Stetter, Univ. of Regensburg (Germany)
George T. Timberlake, Univ. of Kansas Medical Ctr. (United States)
R. A. Sendtner, Univ. of Regensburg (Germany)
Robert H. Webb, Massachusetts General Hospital (United States)

Published in SPIE Proceedings Vol. 2632:
Lasers in Ophthalmology III
Reginald Birngruber; Adolf Friedrich Fercher, Editor(s)

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