Retinal Prosthesis Dissertation - Student Home Pages

microstimulator with a 1:4 demultiplexer built on the electrode array results in 1024-
pixel prosthesis.”, “For 1024 sites, 10 address bits are required. If the stimulus data for
each driver is around 20 bits, this results in 50% increase in the data rate.”, “The chip
consumes around 20 mW when delivering 600 A bi-phasic current pulses of 1 ms
phase widths (anodic, cathodic and interphase delay) at a stimulation rate of 60 Hz.”
[49]
Electrical Stimulation in Isolated Rabbit Retina
“Analysis of the data from this study predicts that a 50- m electrode may have enough
safe charge capacity to evoke a retinal response. “, “With current electrode technology,
more than one thousand 50- m-diameter electrodes could be placed in the macula (5-
mm-diameter area around fovea) . Simulations of prosthetic vision, suggest that face
recognition and reading will be possible with 1000 macular electrodes.”, “Overall,
epiretinal electrodes and subretinal electrodes appear to have similar stimulus pulse
requirements.” [229]
A Biomimetic Retinal Stimulating Array
“.. and in severe cases will lose most of their vision in the central 20º of the visual field.
The macula is the part of the retina that anatomically corresponds to the central 20º of
the visual field”… “When 32 × 32 electrodes were used, the recognition scores
improved to over 80%.” “The electrodes should support 100 nC (100 μA for 1 ms)
pulses without damaging either the electrodes or tissue.”…”Standard visual acuity
testing demonstrated that 20/30 vision could be achieved using 625 pixels in the central
1.7º of the visual field.”… “To accommodate a square arrangement, the electrode must
be reduced to 93µm in order to achieve 1,000 macular electrodes.”
[103]