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The resolution of the device is a tricky question to answer. /u/diashworth's prototype device has a grid of 20 stimulating electrodes that each create a spot of light. These spots of light cover about 12x12degrees of her visual field. We are working on new devices with more electrodes and a wider field of view.

We are definitely up for the challenge! There are lots of things to consider when trying to make electrodes smaller, including finding materials that can be physically made that small and can safely deliver electrical stimulation.

We actually use current stimuli as it allows us to deliver precise amounts of charge. The current levels we use are typically in the microampere range. We deliver the current between two separate electrodes in the eye.

Great question. The electrodes stimulate the nerve pathways of both rods and cones. Each individual electrode actually stimulates a large population of cells, including ones corresponding to red, green & blue, which combine to give whitish spots of light.

There are still lots of questions to answer about how the brain can adapt to make the most out of bionic vision and how users can learn to use the device in their everyday life.