Abstract
Purpose :
While it is known that reduced contrast sensitivity impacts gait on level ground and increases fall-risk, the effect of contrast level of an obstacle in the walkway is unknown. This study investigated the effect of obstacle contrast on foot clearance when stepping over the obstacle.
Methods :
Three young normally sighted adults (mean 24.67 years, SD 2.31) walked along a 30-foot walkway covered in a black carpet. An obstacle was present halfway along the walkway that varied in both height (1 cm and 19 cm) and contrast (6% and 90% Michelson contrast). Subjects were instructed to walk along the path at a self-selected pace and step over the obstacle. Each subject completed 10 trials for each of the 4 conditions. Lower limb kinematics were recorded using 13 motion capture cameras. From the marker position data, foot clearance for the lead and trail foot of each subject was calculated as the distance between the top of the obstacle and the marker placed on the distal toe of the subject’s shoe.
Repeated-measures ANOVAs were run to assess how foot clearance in the lead and trail foot changed as a function of obstacle height and contrast.
Results :
Foot clearance for both the lead (F1,29=270.375, P < .001) and trail (F1,29=87.964, P < .001) foot were significantly higher for the tall versus short height obstacle. There was a trend that foot clearance was greater for the high contrast obstacle compared to the low contrast obstacle; however this difference was not significant for the lead (F1,29=3.635, P =.067) nor the trail (F1,29=1.151, P =.292) foot. The interaction between obstacle height and contrast was not significant for the lead (F1,29=0.011, P =.916) nor trail (F1,29=0.374, P =.545) foot.
Conclusions :
Reduced foot clearance in low versus high contrast obstacles suggest that young adults with normal vision may have difficulty discriminating an obstacle from the ground if its contrast is low. This could increase fall risk from tripping, as the foot may not clear the obstacle. Consistent with previous studies, foot clearance increased with increased obstacle height. However, the contrast of an obstacle did not appear to affect the relationship between foot clearance and obstacle height. Recruitment of normally sighted and vision impaired participants is ongoing to confirm these observations and to identify individuals at greater risk of tripping and falling.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.