A promising new retinal prosthesis using ultrasound to activate neurons could restore vision in patients with retinal degenerative diseases.
“This is a step towards a retinal prosthesis that works without invasive eye surgeries,” said Dr Qifa Zhou, professor of biomedical engineering and ophthalmology at the University of Southern California in Los Angeles. “Special glasses with a camera and an ultrasound transducer are intended to give blind and partially sighted people a new view of the world.”
Bypassing the degenerated photoreceptors in the retina, the researchers investigated if vision could be restored by directly stimulating the retinal neurons using ultrasound. Focusing the high-frequency sounds on a specific area of the eye made it possible for researchers to activate small groups of neurons in a blind rat’s eye, just like light would in a functioning eye. By placing a multi-electrode array in the superior colliculus (the visual area of the brain) and directly connected to the optic nerve, it was possible to record retinal activation by electrophysiology. The study demonstrated that when ultrasound is projected as a pattern on the retina – for example, the letter 'C' – corresponding activities in the superior colliculus were seen.
Study co-lead Professor Mark Humayun, one of the inventors of the Argus II epiretinal implant, said, “The challenge remains to enable ultrasound-elicited visual perception so that it can provide useful vision for the blind.”
The study was published in BMEF (BME Frontiers), and is now at an early stage of developing a device for human trials.
