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<p>Visual prostheses are an emerging technology to restore vision in blind </p><p>individuals.
The level of vision currently attainable with these prostheses is crude and </p><p>far
from the level of normal vision though. Epiretinal prostheses work by using a multi-
</p><p>electrode array implanted within the eye on the inner layer of the retina to
electrically </p><p>stimulate the neural elements beneath the electrodes and produce
punctate visual </p><p>percepts of light called phosphenes. Stimulation by serially
delivering a cathodic </p><p>monopolar pulse of current with each electrode in the
array would require the least </p><p>power to construct pixilated images of the visual
scene. There is the possibility of </p><p>complex stimulation schemes that may be
able to preferentially stimulate the neural </p><p>elements between the electrodes
of the multi-electrode array by utilizing multiple </p><p>electrodes of the array
at once though. Although this would require more power, this </p><p>would effectively
increase the resolution capabilities of the epiretinal prosthesis without </p><p>the
need to increase the number of electrodes on the multi-electrode array. To </p><p>investigate
the possibility of such a stimulation scheme, a computational model of the </p><p>inner
layers of the human retina including the nerve fiber layer and ganglion cells was
</p><p>constructed. The model response was validated against studies of biological
ganglion </p><p>cells, and under comparable conditions reproduced features of epiretinal
stimulation </p><p>seen clinically. The response of the computational model of the
inner retinal layers to </p><p>stimulation by up to two electrodes at once in the
multi-electrode array was then </p><p>determined to evaluate the possibility of producing
phosphenes between the electrodes. </p><p>The investigation found that disk electrodes
using rectangular pulses of equal </p><p>magnitude could not produce a distinct phosphene
between the electrodes of the model.</p>
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