Effects of walking on bilateral differences in spatial attention control: a cross-over design

Influence of postural control difficulty on changes in spatial orienting of attention after leftward prism adaptation

Prism adaptation (PA) affects visuospatial attention such as spatial orienting in both the right and left hemifields; however, the systematic after-effects of PA on visuospatial attention remain unclear. Visuospatial attention can be affected by non-spatial attentional factors, and postural control difficulty, which delays the reaction time (RT) to external stimulation, may be one such factor. Therefore, we aimed to investigate the influence of postural control difficulty on changes in spatial orienting of attention after leftward PA. Seventeen healthy young adults underwent 15-min and 5-min PA procedures for a leftward visual shift (30 diopters). Participants underwent the Posner cueing test immediately before (pre-evaluation) and in between and after the PA procedures (post-evaluations) while standing barefoot on the floor (normal standing condition) and on a balance-disc (balance standing condition). In the pre-evaluation, RTs in the balance standing condition were significantly longer compared to those in the normal standing condition for targets appearing in both the right and left hemifields. Leftward PA improved the RT for targets appearing in the right, but no left, hemifield in the balance standing condition, such that RTs for targets in the right hemifield in the post-evaluation were not significantly different between the two standing conditions. However, leftward PA did not significantly change RTs for targets in both hemifields in the normal standing condition. Therefore, postural control difficulty may enhance sensitivity to the features of the visuospatial cognitive after-effects of leftward PA.

Treadmill-walking impairs visual function in early glaucoma and elderly controls

AIMS

Impaired vision is an additional risk factor in elderly for falls. We investigated the hypothesis that treadmill (TM) walking affects visual function in both healthy elderly and those with early-moderate visual dysfunction due to glaucoma.

METHODS

Thirty healthy controls (HC) aged 64-83 years and 18 glaucoma patients (GLA) aged 62-82 years participated in this cross-sectional study. The impact of TM-walking on visual function was assessed binocularly for (i) best-corrected visual acuity (BCVA) with and without crowding effect, (ii) contrast sensitivity (CS), and (iii) and visual field (mean deviation, VF-MD). Visual function was tested while participants were standing or during TM-walking for 2 speed conditions: (i) fast walking at their preferred speed and (ii) walking at a fixed speed of 3.5 km/h.

RESULTS

GLA, most with early-moderate VF loss, performed equally well as HC. Independent of GROUP, an impact of SPEED on visual functions was statistically evident with large statistical effect size for (i) both types of BCVA with a mean loss of 0.02-0.05 logMAR (η2 = 0.41) and (ii) VF-MD with mean loss of 1 dB (η2 = 0.70), but not for CS.

CONCLUSIONS

Here, we introduce a paradigm for the assessment of visual function during walking. We provide proof-of-concept that our approach allows for the identification of walking induced visual function loss, i.e., a deterioration of BCVA and VF-sensitivity during TM-walking in both groups. It is therefore of promise for the investigation of the relation of vision impairment and mobility, ultimately the increased frequency of falls in advanced glaucoma.