Retinal Prosthesis Dissertation - Student Home Pages

“Medical experiments have estimated that the equivalent impedance for the retina tissue
of RP and AMD patients is about 10kΩ and, in the worst case, the current threshold
value is about 600µA. Thus a voltage drop up to 6v is expected across the retinal
tissue”… “The power consumption in the stimulus chip depends on the image frame
rate. In our application the frame rate is greater than 60 frames/s. The power dissipated
at 100 frames/s, corresponding to a data rate of 40kb/s would be approximately 3mw.”
[53]
On the Thermal Elevation of a 60-Electrode
Epiretinal Prosthesis for the Blind
“In this paper, the thermal elevation in the human body due to the operation of dual-unit
epiretinal prosthesis to restore partial vision to the blind affected by irreversible retinal
degeneration is presented. An accurate computational model of a 60-electrode device
dissipating 97 mW power, currently under clinical trials is developed and positioned in
a 0.25 mm resolution, heterogeneous model of the human head to resemble actual
conditions of operation of the prosthesis.”… “This indicates that it is possible to
position and operate the implant so that the induced temperature increase in the eye over
the body core temperature is less than 2 degree Centigrade.”
[227]
A variable range bi-phasic current stimulus
driver circuitry for an implantable retinal
prosthetic device
“The duration of anodic and cathodic pulses is required to be a maximum of 1ms each.
Effectively any output is on for only 2ms in one stimulation cycle.”
[56]