Abstract
Purpose: :
We have developed a visual prosthesis system called the suprachoridal-transretinal stimulation (STS) system. The purpose of this study was to determine the optimal electrode conditions that would elicit electrically-evoked potentials (EEPs) from the rabbit visual system.
Methods: :
A scleral pocket (3x5 mm) was created just over the visual streak in anesthetized pigmented rabbits (weight, 1.7-2.5 kg). The STS stimulating electrode system was implanted in the pocket. We varied the thickness of the scleral pockets (thick and thin), the pressure over the pocket by placing weights of 0 or 20 g, location of the reference electrodes (0, 90, or 180 degrees from the stimulating electrode), and the length of the reference electrodes (0, 3, or 10 mm). EEPs were then elicited by each type of electrode conditions. Three sessions were repeated for each group.
Results: :
For scleral pockets of 746±301 µm and 234±152 µm thicknesses, the implicit times of the EEPs were 28.5±4.5 ms and 28.9±4.9 ms, respectively, and the amplitudes were 58.9±19.4 µV and 54.3±18.4 µV respectively. These differences were not significant (P=0.881; P=0.660). The pressure over the pockets, the location and the length of the reference electrodes had no significant affect on the implicit times and the amplitudes of the EEPs (P>0.05).
Conclusions: :
The thickness of the scleral pockets, pressure over the pockets, and the location and length of the reference electrode do not significantly affect the implicit times and amplitudes of the EEPs elicited by the STS system.
Keywords: electrophysiology: non-clinical • neuro-ophthalmology: cortical function/rehabilitation • sclera