Non-invasive ultrasound stimulation on the retina and visual cortex for visual restoration

Abstract

Nearly 30% of the U.S. population aged over 75 have age-related macular degeneration and retinitis pigmentosa. 10% of them may become legally blind. Currently, blindness cannot be cured and patients’ living quality can be compromised severely. Electrical visual prostheses are used as the best near-term strategy. However, they have challenges including invasive devices, complex implantation surgeries, and limited resolution. Non-invasive ultrasonic neuromodulation can be a promising technology for non-invasive visual prostheses. Our work showed that direct ultrasound stimulation on the retina can evoke neuron activities in either normal-sighted or retinal degenerated blind rats in vivo, indicating a promising future of ultrasound stimulation as a novel and non-invasive visual prosthesis for translational applications in blind patients. For patients with damaged optic nerves, retinal prostheses are not effective. Thus, we also investigated the feasibility of transcranial focused ultrasound for non-invasive stimulation of the visual cortex to develop a non-invasive cortical visual prosthesis. Besides stimulations, ultrasound has been used to non-invasively monitor brain activity by imaging cortical blood flow. Our study shows that ultrasound-induced visual responses can be monitored by ultrasound flow imaging of the brain, constructing an ultrasound stimulation-recording closed-loop system.