Abstract
Purpose :
Postural stability is an important indicator of a person’s balance ability. However, few studies have examined this function using more real-life scenarios like standing on an uneven surface and reacting to sudden perturbation. Due to peripheral vision loss, we hypothesized that perturbed balance function in patients with glaucoma would be further compromised under a concurrent visual search task.
Methods :
Ten patients with moderate to severe glaucoma in both eyes (mean age ± SD: 66.2 ± 4.4; F/M: 5/5) and ten age-matched healthy subjects (67.2 ± 5.0; F/M: 5/5) were recruited. Perturbed balance performances were assessed using the Computerized Dynamic Posturography (Bertec Balance Advantage™ system), in which the force platform translated in either forward or backward direction. Participants were asked to stand on two support surfaces (firm vs. foam) and perform two visual tasks (fixation vs. target character search). Measurements including root mean square (RMS) sway of center of pressure (CoP) in anterior-posterior (AP) direction, path length, and latency reacting to perturbation were compared across conditions using analysis of variance.
Results :
In line with previous findings, a significant main effect of groups was found in RMS sway (p<0.000), path length (p<0.000), and latency (p=0.015). The glaucoma group showed significantly larger RMS sway, path length and had longer latency compared with the healthy group. A significant main effect of the support surface was found in latency, where participants required a longer reaction time when standing on the foam surface (p<0.001). Surprisingly, the visual search did not significantly alter the balance functions (p>0.10). No significant interaction effects among the group, support surface, and visual task conditions were found (p>0.10).
Conclusions :
Due to reduced peripheral visual information, glaucoma patients had poorer postural stability and required a longer reaction time in response to sudden perturbation. Although reduced somatosensory input by standing on a foam surface further increased participants’ reaction time to perturbation, the effect was similar for healthy and glaucoma groups. Contrary to our hypothesis, the dual task with visual search did not further reduce participants’ perturbed balance control. A possible explanation is that subjects may adopt a posture-first strategy in maintaining their upright posture.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.