June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Head contribution to gaze during outdoor mobility in pedestrians with homonymous hemianopia
Author Affiliations & Notes
  • Shrinivas Pundlik
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Prerana Shivshanker
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
  • Ayush Kumar
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
  • Matteo Tomasi
    EyeNexo, LLC, Massachusetts, United States
  • Kevin Houston
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Alex R Bowers
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Eli Peli
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Gang Luo
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Shrinivas Pundlik BEDx, Code C (Consultant/Contractor), EyeNexo, LLC, Code I (Personal Financial Interest); Prerana Shivshanker None; Ayush Kumar None; Matteo Tomasi None; Kevin Houston None; Alex Bowers None; Eli Peli None; Gang Luo None
  • Footnotes
    Support  R21EY031444
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 1976. doi:
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      Shrinivas Pundlik, Prerana Shivshanker, Ayush Kumar, Matteo Tomasi, Kevin Houston, Alex R Bowers, Eli Peli, Gang Luo; Head contribution to gaze during outdoor mobility in pedestrians with homonymous hemianopia. Invest. Ophthalmol. Vis. Sci. 2023;64(8):1976.

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

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Abstract

Purpose : Head movement is a major component of the overall gaze position when walking outdoors, but quantitative measures are lacking. We analyzed the proportion of head movement for different gaze magnitudes and different conditions in pedestrians with homonymous hemianopia (HH) during naturalistic walking scenarios.

Methods : 19 pedestrians - 7 Left HH (LHH), 6 Right HH (RHH), and 6 with (or history of) Left hemi spatial neglect (LHSN) walked 0.5-mile-long urban routes involving multiple street crossings, while wearing a mobile gaze tracking system (eye & head). Scene videos were used to mark the street crossing segments. Lateral head and gaze positions were obtained with respect to the body midline on the blind side (BS) or seeing side (SS) of the subject. The head movement proportion (Hprop) of the total gaze movement was obtained based on the mean head magnitude binned for every 10° gaze increments ranging from 5° to 105° on either side. Hprop was compared between BS and SS, between street crossings and non-crossing sections, and among the 3 subject groups.

Results : Overall, the Hprop linearly increased with gaze magnitude until around 65°, after which it nearly plateaued. Hprop was significantly larger at street crossings than non-crossing sections for all groups (diff=0.049, p<0.001), with the largest difference seen in the RHH (0.075). There was a significant interaction between subject group and scanning side. Hprop was significantly higher towards the SS than the BS for LHH subjects (diff=0.05, p=0.023), whereas the Hprop was significantly lower toward the SS than their BS (neglect side) in LHSN subjects (diff=-0.05, p<0.001).

Conclusions : During outdoor walking, especially at street crossings, head movements may be the largest driver of gaze shift in pedestrians with HH, as increasingly larger head movements are employed to achieve gaze shifts up to a certain limit. We postulate that this limit, at which the head contribution peaks, is the comfortable head turning limit. Beyond this point, both eye and head movement magnitudes increase to achieve farther gaze shifts, even as their relative contributions remain unchanged. Even for the largest gaze shift, eye movements still account for about one-third of the overall gaze.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Mean head proportion of gaze (Hprop) at street crossings and non-crossing segments, averaged over the subject groups and scanning side factors, for different gaze magnitudes.

Mean head proportion of gaze (Hprop) at street crossings and non-crossing segments, averaged over the subject groups and scanning side factors, for different gaze magnitudes.

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