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BACKGROUND To determine the efficient parameters to evoke electrical phosphenes is essential for the development of a retinal prosthesis. We studied the efficient parameters in normal subjects and investigated if suprachoroidal-transretinal stimulation (STS) is effective in patients with advanced retinitis pigmentosa (RP) using these efficient parameters.(More)
PURPOSE To determine whether wire microelectrodes implanted in the optic disc can be used to elicit cortical potentials. METHODS Two or four platinum wire electrodes of two types, viz., the cut-end type and the exposed-tip type, were inserted through the vitreous and fixed in the optic disc of 16 rabbit eyes. Electrically evoked potentials (EEPs) were(More)
PURPOSE To examine the safety and effectiveness of a retinal prosthesis that is implanted semichronically in two patients with advanced retinitis pigmentosa (RP). METHODS Two eyes of two patients with advanced RP had a retinal prosthesis implanted in a sclera pocket of one eye. The visual acuity of both eyes before the implantation was bare light(More)
PURPOSE Assessment of a novel method of retinal stimulation, known as suprachoroidal-transretinal stimulation (STS), which was designed to minimize insult to the retina by implantation of stimulating electrodes for artificial vision. METHODS In 17 normal hooded rats and 12 Royal College of Surgeons (RCS) rats, a small area of the retina was focally(More)
PURPOSE To investigate whether electrical stimulation of the optic nerve can elicit an electrical evoked potential (EEP) in rabbits and to determine whether such stimulation is a useful approach for the placement of a visual prosthesis. METHODS Two needle-type electrodes were inserted into the optic nerve using a transvitreal approach. For electrical(More)
PURPOSE To determine whether transcorneal electrical stimulation (TES) has neuroprotective effects on photoreceptors and preserves retinal function in Royal College of Surgeons (RCS) rats. METHODS Three-week-old RCS rats received TES through a contact lens electrode on the left eye weekly for 2 to 6 weeks. The right eyes received sham stimulation on the(More)
BACKGROUND A new method of stimulating the retina electrically, called suprachoroidal transretinal stimulation (STS), was shown to be effective in eliciting electrically evoked cortical potentials (EEPs) in Royal College of Surgeons (RCS) rats. Before extending this technique to patients, it is important to determine its safety and feasibility in eliciting(More)
PURPOSE Several approaches for placing an electrode device for visual prosthesis have been previously proposed. In this study, we investigated if transretinal stimulation from the suprachoroidal space can elicit an electrical evoked potential (EEP) in albino rabbits. METHODS A flat electrode array (polyimide plate, platinum electrode) was developed and(More)
PURPOSE To investigate the feasibility of implanting a newly developed suprachoroidal-transretinal stimulation (STS) prosthesis in dogs and to determine its biocompatibility and stability over a 3-month period. METHODS The STS prosthesis system consisted of an array of 49 electrodes (nine were active), an intravitreal return electrode, and an extraocular(More)
The purpose of this study is to determine the threshold suprachoroidal-transretinal stimulation (STS) current that results in retinal damage in rabbits. Biphasic STS pulses (anodic first, frequency 20 Hz) were used to stimulate the retina of pigmented rabbits (n = 18) continuously for 1 h using a 100 microm diameter platinum wire electrode. The STS current(More)