September 2021
Volume 21, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2021
Saccades during visual search: adaptations in the presence of a binocular scotoma
Author Affiliations & Notes
  • Cécile Vullings
    Smith-Kettlewell Eye Research Institute
  • Zachary Lively
    Smith-Kettlewell Eye Research Institute
  • Preeti Verghese
    Smith-Kettlewell Eye Research Institute
  • Footnotes
    Acknowledgements  Supported by a Fulbright grant (C.V.), a Rachel C. Atkinson & C.V. Starr postdoctoral fellowship (C.V.) and a NIH grant NIH R01 EY029730 (P.V.)
Journal of Vision September 2021, Vol.21, 2659. doi:
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      Cécile Vullings, Zachary Lively, Preeti Verghese; Saccades during visual search: adaptations in the presence of a binocular scotoma. Journal of Vision 2021;21(9):2659.

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

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When macular degeneration affects the foveae bilaterally, it results in a binocular scotoma that compromises both high-acuity vision and eye movements. A preferred retinal locus (PRL) is eventually adopted for fixation and oculomotor reference, but individuals still struggle with daily-living tasks as they are sometimes unaware of the location and extent of their scotoma. Here, we use a visual search task to investigate how saccades compensate for the scotoma, which obscures parts of the visual scene. Four individuals with binocular scotomas (BinSc) and 4 age-matched controls participated in our study. We first extensively mapped the BinSc with an eyetracker while fixation was carefully monitored as reported previously. Participants then completed a visual search task where 0, 1, or 2 Gaussian blobs were distributed randomly across a natural scene. Participants reported the number of blobs after 10s of actively searching the display. Search accuracy was principally impacted by the size of the BinSc. All participants made mostly horizontal saccades, but individuals with BinSc made significantly more saccades toward their scotoma than controls for the same directions. Median saccade amplitude was smaller for individuals with BinSc and therefore, when directed toward the scotoma, saccades were aimed more at the scotoma edge closest to the PRL. Thus, multiple sequential saccades were necessary to fully uncover the region hidden by a large scotoma. Instead of adopting such a strategy, participants frequently made backward saccades directed to newly uncovered regions. Critically, this tendency was more likely following a saccade toward the BinSc rather than toward an already visible region. Individuals with BinSc seem to adopt a strategy to explore locations uncovered by having previously looked toward their scotoma. Our extensive analyses of saccade characteristics during visual search was made possible by the detailed mapping of the shape, size and location of the binocular scotoma.


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