A new primary mobility tool for the visually impaired: A white cane-adaptive mobility device hybrid.

This article describes pilot testing of an adaptive mobility device-hybrid (AMD-H) combining properties of two primary mobility tools for people who are blind: the long cane and adaptive mobility devices (AMDs). The long cane is the primary mobility tool used by people who are blind and visually impaired for independent and safe mobility and AMDs are adaptive devices that are often lightweight frames approximately body width in lateral dimension that are simply pushed forward to clear the space in front of a person. The prototype cane built for this study had a wing apparatus that could be folded around the shaft of a cane but when unfolded, deployed two wheeled wings 25 cm (9.8 in) to each side of the canetip. This project explored drop-off and obstacle detection for 6 adults with visual impairment using the deployed AMD-H and a standard long cane. The AMD-H improved obstacle detection overall, and was most effective for the smallest obstacles (2 and 6 inch diameter). The AMD-H cut the average drop off threshold from 1.79 inches (4.55 cm) to .96 inches (2.44 cm). All participants showed a decrease in drop off detection threshold and an increase in detection rate (13.9% overall). For drop offs of 1 in (2.54 cm) and 3 in (7.62 cm), all participants showed large improvements with the AMD-H, ranging from 8.4 to 50%. The larger drop offs of 5 in (12.7 cm) and 7 in (17.8 cm) were well detected by both types of canes.

Drop-off detection with the long cane: effect of cane shaft weight and rigidity on performance.

Most travellers who are blind rely on a long cane to detect drop-offs on their walking paths. We examined how different cane shaft materials affect drop-off detection performance through providing different vibrotactile and proprioceptive feedbacks to the cane user. Results of the study showed a significant interaction between cane shaft weight and how the cane is used. A heavier cane was advantageous for detecting drop-offs when the individual used the 'constant contact technique' - cane tip stays in contact with the walking surface at all times - but not when he used the 'two-point touch technique' - cane tip is rhythmically tapped on the surface. In addition, a more flexible cane was advantageous for detecting drop-offs when the two-point touch technique was used but not when the constant contact technique was used. It is recommended that, when blind individuals select a cane shaft material, they consider which long cane technique they use more often. Practitioner Summary: Long cane shaft material affects how well a blind individual can detect drop-offs. A heavier shaft was advantageous when using the constant contact technique (cane tip stays in continuous contact with the surface), while a more flexible shaft was better when using the two-point touch technique (cane tip rhythmically taps the surface).

Traffic gap detection for pedestrians with low vision.

PURPOSE: Pedestrians with low vision have identified crossing the street as a difficult task. With the increasing complexity of the crossing environment (actuated signals and roundabouts), the challenges are increasing. The purpose of this study was to evaluate the effect of two types of vision loss (central or peripheral) on the ability to detect gaps in traffic. METHODS: Forty-one subjects participated with 14 being fully sighted (FS), 10 having central vision loss from age-related macular degeneration (AMD), and 17 having peripheral vision loss from either retinitis pigmentosa or glaucoma. Standing at entry and exit lanes of a roundabout, subjects depressed a handheld trigger to indicate when there was a sufficient gap in traffic to cross the street. A total of twelve 2-min intervals were completed including four of those intervals with occluded hearing. RESULTS: No difference was found in the ability of the three subject groups to identify crossable or short gaps. There were significant differences in latency and safety margin. The AMD subjects did not perform as well as the FS or the subjects with retinitis pigmentosa/glaucoma. When hearing was occluded, the two vision loss groups did not show a change in sensitivity but the FS group did, being more sensitive when hearing was occluded. CONCLUSIONS: The purpose of this study was to evaluate the effect of low vision on the ability to detect crossable gaps in traffic. The findings suggest that subjects with AMD have an increased risk because they show significant latency in their identification of gaps and this in turn results in a reduction of safety margin.