The new system — known as the BrainPort vision device — was developed by the Centre for Vision Restoration for the US Armed Forces Institute of Regenerative Medicine (AFIRM) and is being trialled in the UK by retired Lance Corporal, Craig Lundberg, who served with 2nd Battalion The Duke of Lancaster’s Regiment.
Lundberg was hit by a rocket-propelled grenade in March 2007 while he was serving in Basra. As a result of the explosion his left eye had to be removed and his right eye was severely damaged, leaving him profoundly blind.
The BrainPort vision device works on the principle of sensory substitution; in this instance the touch sensors of the tongue are used instead of the photoreceptors of the eye.
To use the system, the patient wears a pair of glasses which carry a video camera. Images are fed into a device that is held in the mouth and transforms the pictures into electrical impulses that are felt on the tongue.
The sensation is a tingling of different intensities that correspond to the relative darkness of the pixels recorded on the camera, allowing him to perceive light and dark and negotiate his way around objects.
Lundberg and Wing Commander Rob Scott, his military eye doctor, spent two weeks at the University of Pittsburgh Medical Centre in 2009 learning how to use and train on the device.
‘I could feel with my tongue that the first letter was an ’A’, and then I moved onto the next one,’ said Lundberg, describing the tests. ‘Then I walked down a corridor and I could make out the doorways, the walls and people coming towards me.
‘It was the first time since Iraq that I had been able to do that. The equipment needs a lot of work, but it has got huge potential.’
Scott and Lundberg will now trial the device at the Birmingham Midland Eye Centre and the Royal Centre for Defence Medicine, where Lundberg will undergo further training.
‘If this technology is going to work at all, I believe it has to be developed through blind people for blind people,’ said Scott. ‘I am waiting to see how it works with Craig and if it is a success we can start extending the project to include other blind service people.’
The images above demonstrate how information from the video camera is represented on the tongue. Today’s prototypes have 400 to 600 points of information on a ~3cm x 3cm tongue display, presented at approximately 30 frames per second
How does the BrainPort vision device work?
The BrainPort vision system consists of a postage-stamp-size electrode array for the top surface of the tongue (the tongue array), a base unit, a digital video camera, and a handheld controller for zoom and contrast inversion.
Visual information is collected from the user-adjustable head-mounted camera (FOV range 3–90 degrees) and sent to the BrainPort base unit.
The base unit translates the visual information into a stimulation pattern that is displayed on the tongue.
The tactile image is created by presenting white pixels from the camera as strong stimulation, black pixels as no stimulation, and grey levels as medium levels of stimulation, with the ability to invert contrast when appropriate.
With the current system (arrays containing 100 to 600+ electrodes), study participants have been able to recognise high-contrast objects, their location, movement, and some aspects of perspective and depth.
Trained blind participants use information from the tongue display to augment understanding of the environment.
Source: Wicab, Inc
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