The BrainPort V100, a medical device that claims to help blind people "see" with their tongues, has been approved by the U.S. Food and Drug Administration (FDA).
Developed by Middleton, Wis.-based Wicab, the device translates visual information from a video camera into gentle electrical stimuli for the tongue. Eventually, users are able to interpret the signals to "see" where objects are located, how big they are, and how quickly and in what direction they are moving.
About two million optic nerves are required to transmit visual signals from the retina—the portion of the eye where light information is decoded or translated into nerve pulses—to the brain's primary visual cortex. With BrainPort, visual data are collected through a small digital video camera about 1.5 centimeters in diameter that sits in the center of a pair of sunglasses worn by the user. Bypassing the eyes, the data are transmitted to a handheld base unit, which is a little larger than a cell phone. This unit houses such features as zoom control, light settings and shock intensity levels as well as a central processing unit (CPU), which converts the digital signal into electrical pulses—replacing the function of the retina.
From the CPU, the signals are sent to the tongue via a "lollipop," an electrode array about nine square centimeters that sits directly on the tongue. Each electrode corresponds to a set of pixels. White pixels yield a strong electrical pulse, whereas black pixels translate into no signal. Densely packed nerves at the tongue surface receive the incoming electrical signals, which feel a little like Pop Rocks or champagne bubbles to the user. It remains unclear whether the information is then transferred to the brain's visual cortex, where sight information is normally sent, or to its somatosensory cortex, where touch data from the tongue is interpreted, Wicab neuroscientist Aimee Arnoldussen said.
Within 15 minutes of using the device, blind people can begin interpreting spatial information via the BrainPort, says William Seiple, research director at the nonprofit vision healthcare and research organization Lighthouse International. The electrodes spatially correlate with the pixels so that if the camera detects light fixtures in the middle of a dark hallway, electrical stimulations will occur along the center of the tongue.
"It becomes a task of learning, no different than learning to ride a bike," Arnoldussen noted, adding that the "process is similar to how a baby learns to see. Things may be strange at first, but over time they become familiar."
The key to the device may be its utilization of the tongue, which seems to be an ideal organ for sensing electrical current. Saliva there functions as a good conductor, Seiple said. Also it might help that the tongue's nerve fibers are densely packaged and that these fibers are closer to the tongue's surface relative to other touch organs. (The surfaces of fingers, for example, are covered with a layer of dead cells called stratum corneum.)
Clinical data supporting the safety and effectiveness of the BrainPort V100 included several assessments, such as object recognition and word identification, as well as oral health exams to determine risks associated with holding the intra-oral device in the mouth. Studies showed that 69 percent of the 74 subjects who completed one year of training with the device were successful at the object recognition test. Some patients reported burning, stinging or metallic taste associated with the intra-oral device. There were no serious device-related adverse events.
"Medical device innovations like this have the potential to help millions of people," William Maisel, chief scientist at the FDA's Center for Devices and Radiological Health, said. "It is important we continue advancing device technology to help blind Americans live better, more independent lives."
Wicab received permission to sell the BrainPort V100 in Europe in 2013 after 15 years of research. Now, it can be marketed in the United States, where, according to the National Institutes of Health, 1.2 million people are blind.