August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Dilation can minimize pupil-induced fixational drift.
Author Affiliations
  • Kevin Willeford
    NOVA Southeastern College of Optometry
  • Victoria Georges
    Mila - Québec AI Institute, Montréal, QC, Canada
Journal of Vision August 2023, Vol.23, 5651. doi:
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      Kevin Willeford, Victoria Georges; Dilation can minimize pupil-induced fixational drift.. Journal of Vision 2023;23(9):5651.

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      © ARVO (1962-2015); The Authors (2016-present)

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Introduction. Gaze-dependent patterns of binocular misalignment are used to diagnose extraocular muscle pareses; however, utilizing video-based eye trackers for this analysis is challenging because erroneous patterns may arise when an observer’s pupil changes size during the experiment. This can introduce bias across time (i.e., the pupil-size artifact) and/or gaze positions (e.g., variable pupil foreshortening errors). The goal of our experiment was to quantify the influence of both phenomena on the repeatability of gaze-estimates and to determine whether pharmacological dilation could reduce any biases present. Methods. The Eyelink 1000 Plus (Tower Mount) was used in conjunction with a bite-bar apparatus to measure the eye position and pupil size of twenty-eight observers. Measurements were repeated at twenty-five gaze positions (10° x 10° grid) across twenty two-minute blocks. Eye positions and pupil sizes were referenced to the first block and then averaged across gaze-positions (for each block) and across blocks (for each gaze position) to determine whether spatiotemporal associations between changes in eye position and changes in pupil size existed. The same analysis was then performed for two observers with dilated pupils. Results. Progressive pupillary constrictions were associated with progressive rightward and leftward drifts in position for the left- and right-eyes, respectively. A progressive upward drift in both eyes was also associated with a sequential reduction in pupil size. On the other hand, the continuous miosis was not associated with any gaze-dependent shifts in eye position. Dilation prevented any sequential change in pupil size from occurring and thus improved the repeatability of gaze-estimates across time. Conclusions. Fluctuations in pupil size contribute to fixational drift; however, this can be minimized by pharmacological dilation which maintains the validity of the initial calibration across time.


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