Evaluating Associations Between Central Visual Field Loss and Conscious Movement Processing

Central visual field loss (CFL) due to diseases such as age-related macular degeneration (AMD) is a large and growing problem. While much is known about the visual limitations associated with this condition, one of its most dangerous and poorly understood outcomes is the increase in the risk of falls, which can be debilitating and even deadly. Recent studies suggest that older adults deemed to be at an increased risk of falls may alter their movement processing strategies (Wong et al. 2008). Specifically, heightened conscious movement processing and task-irrelevant ruminations are observed; both of which are linked to increased fall-related anxiety and increased movement errors when walking (Ellmers et al. 2019). These behaviors are also linked with maladaptive visual search strategies (i.e. reducing previewing of an intended walking path) during locomotion that may further increase the risk of trips, slips and falls. The current study sought to evaluate if similar conscious movement processes emerge in individuals with CFL and if these changes are related to the extent of visual deficit.
To assess changes in movement processing we used the Gait-Specific Attentional Profile (G-SAP, Young et al. 2020). Items on this scale were divided in to three sub-scales: conscious movement processing, anxiety, and rumination. The total score for each category was calculated separately for each participant and correlated with measures of binocular contrast sensitivity (MARS letter test) and visual acuity (VA) of the better eye. A total of 29 individuals with CFL (18 F) were surveyed for the study. We found binocular contrast sensitivity to be a significant predictor of increases in conscious movement processing during locomotion in individuals with CFL (linear regression, p = 0.037). Additionally, VA of the better eye was a strong predictor of an increase in anxious thoughts during locomotion (p = 0.041). The latter may be related to previously-reported increases in overall fear of falling in individuals with AMD (van Landingham et al. 2014). These findings suggest that further experiments are needed to investigate potentially dangerous behavioral changes in gaze strategies and posture in patients with CFL associated with increased conscious monitoring of movements during locomotion.