February is AMD awareness month. No, it is not the chip manufacturer. AMD refers to Age-related Macular Degeneration. About 39 million people worldwide live with some form of degenerative disease that leads to blindness or vision loss. Approximately 2.2 billion people worldwide are afflicted with a visual impairment or blindness. About 80 million are living with some form of glaucoma. (reference the World Health Organization.)
The prospect of treating blindness with neurotechnology is still in the early stages of development but there are some visual prosthesis on the market in specific areas around the world. In general, the human visual sense is complex and intricately wired. Also, the amount of information that must be coded and transmitted in visual perception is no easy task. Nonetheless, there are several commercial firms and research laboratories developing neural prostheses that restore some level of visual function.
One of the pioneers in the field is the Artificial Retina team. Within that group are names like Mark Humayun from the University of Southern California Roski Eye Insitute, Jim Weiland from the University of Michigan, Robert Greenberg formerly from Second Sight, and Wentai Liu from the University of California Los Angeles. Other research teams developing an epiretinal device include the RWTH Aachen University and the University of Ulm in Germany as well as KN Toosi University of Technology in Iran.
The Bionic Vision Lab team lead by Michael Beyeler from the Unversity of California, Santa Barbara is developing a subretinal visual prosthesis. Also pursuing this concept are teams at Tubingen University in Germany and Philip Troyk’s team at the Illinois Institute of Technology in the U.S. Pixium Vision based in Paris, France is developing a commercial device, PRIMA, using this approach.
An alternative approach is to directly stimulate the optic nerve. Three teams are exploring this option, in Australia at the University of Melbourne & Australian National University, in Belgium at Catholique Universite de Louvain, and in China out of China’s Shanghai Jiao-Tong University.
One advantage of subretinal implants over other approaches is the topological fidelity with the point of stimulation. Epiretinal implants must use image processing algorithms to adjust the image coming from an external camera before stimulating the retina. Subretinal implants are positioned at the level of the photoreceptor layer and can thus make full, correct use of the retinotopy of bipolar cells linked to it. With the subretinal approach, light receivers are located beneath the retina, and assistance is provided by natural microsaccades which constantly refresh the image. In addition, the eye’s direction of gaze can be used to find the object viewed without need of resorting to movement of the head.
The other main approach to restoring vision is by stimulating the visual cortex within the human brain. In this method information is transcutaneously (on the surface of the skin) transferred from an external image capture system, processed, and cortically stimulated within the brain. Teams leading this effort are based at the Dobelle Institute in Portugal, the Polytechnique Montreal University in Canada, and in the U.S. at the University of Utah and the Illinois Institute of Technology. Second Sight is developing a commercial device with its Orion system and plans to address a wider array of visual impairments such as glaucoma, optic nerve injury and forms of cancer.
There are other approaches in the research stage. A team of researchers from Massachusetts General Hospital, Harvard Medical School, the University of Florida, and Xerox PARC is developing a new visual prosthetic platform for restoring high levels of visual acuity. In 2017, Applied Genetic Technologies Corp., a public biotechnology firm conducting human clinical trials of adeno-associated virus-based gene therapies, announced that it entered into a strategic research and development collaboration with Bionic Sight, an optogenetics startup developing visual neuroprosthetics based on the company’s retinal coding technology.
Companies that are developing implanted or external visual prostheses include Second Sight, Qura, Bionic Vision Technologies, Pixium Vision, Nano Retina, Magna Vision and EBS Technologies.
There is another area of neurotech for vision loss categorized as neural rehabilitation tools. Common in stroke and traumatic brain injury survivors, visual impairment can often occur. This may lead to complete vision loss but more commonly is a visual impairment, meaning a life altering condition. In some cases, rehabilitation tools may be used to help restore some and, in some cases, all vision. Tools such as the Bioness Integrated Therapy System (BITS) can be found in rehabilitation centers and used as a tool to aid in the recovery process.
Neurotech Network offers free resources and a directory of devices specifically for blindness, vision disorders and impairments. Check out our page here.