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Björn Hammar, MD, PhD. Photo.

Björn Hammar

Specialist physician

Björn Hammar, MD, PhD. Photo.

A robust method for calibration of eye tracking data recorded during nystagmus

Author

  • William Rosengren
  • Marcus Nyström
  • Björn Hammar
  • Martin Stridh

Summary, in English

Eye tracking is a useful tool when studying the oscillatory eye movements associated with nystagmus. However, this oscillatory nature of nystagmus is problematic during calibration since it introduces uncertainty about where the person is actually looking. This renders comparisons between separate recordings unreliable. Still, the influence of the calibration protocol on eye movement data from people with nystagmus has not been thoroughly investigated. In this work, we propose a calibration method using Procrustes analysis in combination with an outlier correction algorithm, which is based on a model of the calibration data and on the geometry of the experimental setup. The proposed method is compared to previously used calibration polynomials in terms of accuracy, calibration plane distortion and waveform robustness. Six recordings of calibration data, validation data and optokinetic nystagmus data from people with nystagmus and seven recordings from a control group were included in the study. Fixation errors during the recording of calibration data from the healthy participants were introduced, simulating fixation errors caused by the oscillatory movements found in nystagmus data. The outlier correction algorithm improved the accuracy for all tested calibration methods. The accuracy and calibration plane distortion performance of the Procrustes analysis calibration method were similar to the top performing mapping functions for the simulated fixation errors. The performance in terms of waveform robustness was superior for the Procrustes analysis calibration compared to the other calibration methods. The overall performance of the Procrustes calibration methods was best for the datasets containing errors during the calibration.

Department/s

  • Department of Biomedical Engineering
  • Lund University Humanities Lab
  • eSSENCE: The e-Science Collaboration
  • Ophthalmology Imaging Research Group

Publishing year

2020-02

Language

English

Pages

36-50

Publication/Series

Behavior Research Methods

Volume

52

Issue

1

Document type

Journal article

Publisher

Springer

Topic

  • Ophthalmology
  • Medical Laboratory and Measurements Technologies

Keywords

  • Calibration
  • Eye tracking
  • Nystagmus

Status

Published

Research group

  • Ophthalmology Imaging Research Group

ISBN/ISSN/Other

  • ISSN: 1554-3528