Alarm device helps partially sighted to walk and avoid collisions

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US researchers develop an audible walking navigation aid for people with field of vision impairment, based on time-to-collision

An audible alarm system that warns partially-sighted people of impending collisions could make a valuable contribution to them navigating through crowded environments safely and comfortably, according to its developers at the Schepens Eye Research Institute at Massachusetts Eye and Ear Hospital. The device is wearable or can be carried in a pocket, and is claimed to be particularly useful for people who have suffered brain injury or other conditions which limit their visual field.

Guang Luo of Schepens Eye Research Institute adjusts the collision-alert device

The device works by using machine vision to predict time to impact with an obstacle rather than proximity, explained senior researcher Guang Luo. ‘It gives warnings only when the users approach to obstacles, not when users stand close to objects and not when moving objects just pass by,’ he added. ‘So, the auditory collision warnings given by the device are simple and intuitively understandable.’

People suffering from conditions like tunnel vision or hemianopia, when half of the visual field is lost, are particularly prone to falls and collisions; and therapies to restore vision are still in their infancy, making technological solutions an attractive option. Luo’s team, who discuss their research in Investigative Opthalmology and Visual Science, tested the device by asking people with visual conditions (or using devices that mimicked them) to walk through an obstacle course both with and without the warning device. They found that using the device reduced collisions by 37 per cent, with barely any change in walking speed, and no patients had more collisions when using the device than without it.

‘We are excited about the device’s potential value for helping visually impaired and completely blind people walk around safely,’ Luo said in a statement. ‘Our next job is to test its usefulness in patients’ daily lives in a clinical trial study.’