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Diamond Brunt, YINGZI XIONG, Gordon E Legge; Impacts of Vision and Hearing Impairment on Egocentric Straight-ahead. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3573.
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Egocentric perception of straight-ahead is an important internal reference for spatial orientation. For people with sensory impairment who receive reduced external sensory input, such internal reference may affect mobility and judgments of spatial layout. This study investigates the impacts of vision and hearing impairment on the perception of egocentric straight-ahead and the relationship to real-life tasks such as walking without veering.
Subjects with vision impairment (VL, N = 9), dual sensory impairment (DSL, combined vision and hearing impairment, N = 6), and healthy controls (N = 6) participated in this study. Across all subjects, the acuity ranged from -0.14 to 1.66 logMAR, the contrast sensitivity ranged from 0 to 2.25 logCS, and the hearing threshold ranged from -1.3 to 55 dB. The egocentric straight-ahead was measured in three modalities: proprioception, vision and audition. In measuring proprioception, subjects closed their eyes and pointed to their perceived straight-ahead. To measure vision and audition, subjects adjusted a LED light or clicking sound in the horizontal plane to their perceived straight-ahead. Each condition was tested with eight trials. The center point between the two eyes was measured as the reference for body center. Bias was calculated as the mean error in the angle between the reported straight-ahead and a straight-ahead line defined by body center. Precision was calculated as the standard deviation across the eight trials
There was no significant group difference in bias in any of the three modalities. The biases were also not significantly related to hearing asymmetry, hearing threshold, binocular acuity or contrast sensitivity. When comparing the precision, only the auditory condition showed a significant group difference. Post-hoc analysis showed that the control group had significantly higher precision than both VL and DSL groups. Hearing threshold and binocular acuity were both significant predictors for the auditory precision, with higher hearing threshold and worse acuity related to reduced precision.
Our preliminary results showed that vision and hearing impairment did not significantly affect the perception of proprioceptive and visual straight-ahead, but both reduced the precision of auditory straight-ahead. The impacts of vision and hearing impairment on other real-life tasks such as walking without veering is currently under investigation.
This is a 2021 ARVO Annual Meeting abstract.
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