Citation

Pundlik S, Tomasi M, Houston KE, Kumar A, Shivshanker P, Bowers AR, Peli E, Luo G. Invest. Ophthalmol. Vis. Sci. 2024; 65(8): e46.

Copyright

(Copyright © 2024, Association for Research in Vision and Ophthalmology)

DOI

10.1167/iovs.65.8.46

PMID

39078731

PMCID

PMC11290574

Abstract

PURPOSE: The purpose of this study was to investigate gaze-scanning by pedestrians with homonymous hemianopia (HH) when walking on mid-block sidewalks.

METHODS: Pedestrians with right homonymous hemianopia (RHH), and left homonymous hemianopia (LHH) without and with left spatial neglect (LHSN) walked on city streets wearing a gaze-tracking system. Gaze points were obtained by combining head movement and eye-in-head movement. Mixed-effects regression models were used to compare horizontal gaze scan magnitudes and rates between the side of the hemi-field loss (BlindSide) and the seeing side (SeeingSide), among the three subject groups, and between mid-block walking and street crossing segments.

RESULTS: A total of 7021 gaze scans were obtained from 341 minutes of mid-block walking videos by 19 participants (6 with LHH, 7 with RHH, and 6 with LHSN). The average gaze magnitude and scanning rate in mid-block segments were significantly higher towards the BlindSide than the SeeingSide in LHH (magnitude larger by 1.9° (degrees), P = 0.006; scan rate higher by 4.2 scans/minute, P < 0.001) and RHH subjects (magnitude larger by 3.3°, P < 0.001; scan rate higher by 3.2 scans/minute, P = 0.002), but they were not significantly different in LHSN subjects. The scanning rate, in terms of scans/minute (mean, 95% confidence interval [CI]) was significantly lower in LHSN subjects (mean = 6.9, 95% CI = 5.6-8.7) than LHH (mean = 10.2, 95% CI = 8.0-13.1; P = 0.03) and RHH (mean = 11.1, 95% CI = 9.0-13.7; P = 0.007) subjects. Compared to street-crossings, the scan rate during the mid-block segments was lower by 3.5 scans/minute (P < 0.001) and the gaze magnitude was smaller by 3.8° (P < 0.001) over the 3 groups.

CONCLUSIONS: Evidence of compensatory scanning suggests a proactive, top-down mechanism driving gaze in HH. The presence of spatial neglect (SN) appeared to negatively impact the top-down process.

Language: en

Keywords

Humans; Adult; Aged; Female; Male; Middle Aged; Aged, 80 and over; *Pedestrians; *Fixation, Ocular/physiology; *Hemianopsia/physiopathology/diagnosis; *Perceptual Disorders/physiopathology/etiology; *Visual Fields/physiology; Eye Movements/physiology; Eye-Tracking Technology; Head Movements/physiology; Walking/physiology