Perception of Straight Ahead With Vision, Hearing, and Proprioception by Individuals With Low Vision.

Purpose: The perception of straight ahead (PSA) is an important reference for spatial orientation. Although individuals with low vision often report difficulties in spatial tasks, it is not clear whether they face challenges in defining PSA. We asked whether low vision leads to increased biases and variabilities in visual PSA, and whether these changes, if any, would generalize to auditory PSA, due to the dominant role of vision in spatial tasks. Methods: Thirty-five low-vision participants and 17 age-matched control participants completed visual and auditory PSA tasks in which they adjusted the location of a brief LED light or a finger snap sound from a speaker to appear to be straight ahead. To control for proprioception, participants also completed a PSA task in which they pointed to their straight ahead while blindfolded. Results: The magnitudes of biases and variabilities in visual PSA were significantly associated with binocular acuity and contrast sensitivity, but the laterality of the visual biases was not associated with interocular asymmetries in acuity, contrast sensitivity, or lateral asymmetries in the binocular visual field. Low-vision individuals showed larger magnitudes of biases and variabilities in the auditory PSA independent of age or hearing status, possibly indicating a cross-modal impact of vision loss on sound localization. Despite the changes in visual and auditory PSA, the low-vision participants showed intact proprioception PSA. Conclusions: The changes in visual and auditory PSA may contribute to spatial orientation challenges encountered by low-vision individuals, and the robust proprioceptive PSA may play an important compensatory role.