A flexible high-precision photoacoustic retinal prosthesis.

Retinal degenerative diseases of photoreceptors are a leading cause of blindness with no effective treatment. Retinal prostheses seek to restore sight by stimulating remaining retinal cells. We here present a photoacoustic retinal stimulation technology. We designed a polydimethylsiloxane and carbon-based flexible film that converts near-infrared laser pulses into a localized acoustic field, aiming at high-precision acoustic activation of mechanosensitive retinal cells. This photoacoustic stimulation of wild-type and degenerated ex vivo retinae resulted in robust and localized retinal ganglion cell activation with sub-100-µm resolution in both wild-type and degenerated ex vivo retinae. Our millimeter-size photoacoustic film generated neural activation in vivo along the visual pathway to the superior colliculus, as measured by functional ultrasound imaging when the film was implanted in the rat subretinal space and stimulated by pulsed laser. Biosafety of the film was indicated by absence of short-term adverse effect under optical coherence tomography retinal imaging, while local thermal increase was measured below 1 °C. These findings demonstrate the potential of our photoacoustic stimulation for visual restoration in blind patients with a high spatial precision and a large field of view.