Objective: To demonstrate that an epiretinal prosthesis can produce patterned visual perception in patients blinded by photoreceptor degeneration who have no other treatment options.
Methods: A totally blind subject with retinitis pigmentosa had a 16-electrode epiretinal prosthesis implanted. The implant is controlled wirelessly by an external computer or a head-mounted video camera. Spatial vision was assessed by measuring the subject's response to direct stimulation of patterns and by comparing the ability of the subject to identify the orientation of gratings with the system on and off.
Results: In response to stimulation of 2 orthogonal rows of electrodes, the subject drew 2 lines with a mean (SEM) angle of 87.4 degrees (1.8 degrees) between them. With the system on, the subject identified the orientation of the grating target up to a spatial resolution that matches the spacing between the adjacent electrodes. In contrast, with the system off, the subject could not detect or identify the target's orientation.
Conclusion: Synchronized stimulation of different retinal locations with an epiretinal prosthesis implanted long-term can produce spatial vision with an acuity level determined by the distance between the electrodes.
Trial registration: clinicaltrials.gov Identifier: NCT00279500.