| abstract |
A retinal prosthesis that provides power control capabilities through the temporal integration of electrical charge is provided. The retinal prosthesis comprises at least one stimulating component, each stimulating component in turn comprising a photojunction element (e.g., a photodiode) in electrical communication with an electrode. A pulse generation circuit provides a reverse-bias signal and, from time to time, a pulsatile forward-bias signal to the photojunction element. During application of the reverse-bias signal, light incident upon the photojunction element causes electrical charge to be accumulated. Upon application of the pulsatile forward-bias signal, the accumulated electrical charge is injected via the electrode into retinal tissues, thereby stimulating the retina. By appropriately selecting the bias signal parameters, a sufficient amount of charge may be accumulated to ensure reaching stimulation thresholds. In this manner, control over stimulus currents may be improved while still retaining advantageous use of the eye's natural focusing and imaging capabilities. |