Non-invasive Ultrasound Stimulated Retinal Prosthesis

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Abstract Age-related macular degeneration and retinitis pigmentosa lead to loss of retinal photoreceptor cells, causing blindness in thousands of people each year. Retinal prosthetic devices treat these incurable conditions by electrically or chemically stimulating surviving retinal neurons with implanted devices in the eye. However, existing devices are very expensive, invasive, and require complex implantation surgeries. Here we propose to explore a new approach in retinal prosthetics that is entirely noninvasive. Previous studies have demonstrated the feasibility of ultrasound to elicit neural activity in the rat hippocampus and motor cortex, and salamander retina cell. We recently demonstrated that a focused single element ultrasound transducer can elicit spiking activity in mammalian retinal neurons. In order to develop potential ultrasound prosthetic devices, we have to overcome several technical challenges: 1) Engineer an ultrasound device that is safe and effective (i.e., optimized) for retinal stimulation. 2) Develop three-dimensional mapping of neural activity in the retinal neural network under acoustic stimulation. Such an imaging method is essential for studying the biological mechanism of ultrasound stimulation and functional evaluation of ultrasound stimulation protocols. The goal of this study is to develop ultrasound stimulation by using phased array that can potentially replace invasive prosthetic electrical stimulation for retina. The first, we will develop specialized ultrasonic single- element transducer/phased arrays for retinal stimulation; we will design an optimal ultrasound stimulation paradigm to produce controllable and consistent retinal responses with high spatiotemporal resolution. The purpose of this study is two-fold: 1) to investigate biophysical mechanisms of ultrasound stimulation on retinal neurons, and 2) to conduct functional testing of the ultrasound devices developed. Finally, in vitro and in vivo rabbit studies using integrated ultrasound stimulation will be developed.