Abstract
Purpose :
Individuals with central visual field loss (CFL) often limit their physical activity due to poor vision and a fear of falling. There are known mobility deficits in CFL, though their extent is not well characterized and often attributed to aging. The Timed Up and Go (TUG) is a common test of mobility and fall-risk. In it, an individual is asked to stand from a seated position, walk 3m, turn, and sit back down while being timed. Some studies suggest that those with CFL perform worse on the TUG than age-matched controls. Despite its common use, the TUG’s diagnostic accuracy for fall risk is questionable. Thus, with the rise of lightweight wearable technology, the instrumented TUG is increasingly used to obtain objective, quantifiable postural and gait measures that are more sensitive to mobility changes, often examining head and trunk acceleration and its variability. In this preliminary study, we used the instrumented TUG to characterize performance with respect to visual function in healthy older adults with and without CFL.
Methods :
Four older adults with no visual disorders (3F, 75.8 ± 4.1 y.o.) and 9 individuals with CFL (3F, 71.2 ± 8.5 y.o.) performed the TUG 3 times with wireless inertial measurement units on the head, chest, and right ankle (latter used for step detection). We examined median acceleration and acceleration variability (median absolute deviation, MAD) of the head and trunk in the frontal plane during straight and turning phases of the TUG. We performed partial correlations accounting for age and phase duration between visual acuity and the acceleration metrics.
Results :
We did not find significant kinematics or time differences on the TUG between controls and those with CFL. The head and trunk acceleration metrics were closely correlated on the straight walking (p<0.05, 0.80<r<0.93) but not when turning (median and MAD). Interestingly, a significant negative correlation was found between visual acuity and head and trunk acceleration variability during straight walking only (p<0.05, -0.79<r<-0.64).
Conclusions :
Our data suggest that with poorer visual acuity, individuals adapt their walking behavior toward a more consistent head and trunk motion that would allow for a more predictable motion of the visual scene. Experiments are ongoing to include additional visual deficit metrics, such as scotoma size and viewing eccentricity.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.