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M. Kamei, T. Fujikado, H. Kanda, T. Morimoto, K. Nakauchi, H. Sakaguchi, Y. Ikuno, M. Ozawa, S. Kusaka, Y. Tano; Suprachoroidal–Transretinal Stimulation (STS) Artificial Vision System for Patients with Retinitis Pigmentosa . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1537.
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© ARVO (1962-2015); The Authors (2016-present)
We have developed the Suprachoroidal–Transretinal Stimulation (STS) artificial vision system and demonstrated its effectiveness and safety in vivo. We now report a preliminary clinical trial of the STS system to patients with retinitis pigmentosa (RP).
Two RP patients with a visual acuity of light perception were enrolled. After dissection of lateral rectus muscle insertion, a scleral pocket of 5x5 mm was made posterior to the inferior oblique muscle insertion. A 9–channel electrode array (4x5 mm) was inserted into the scleral pocket and a wire reference electrode (<font face="symbol">f</font> 0.1mm) was inserted into the vitreous cavity through the pars plana. Biphasic pulses (duration: 0.5 or 1.0 ms, frequency: 20 Hz) were applied through selected channel(s). The size and shapes of phosphene described by the patients were recorded. All procedures were performed under topical anesthesia (20mg of fentanest iv was used on Patient 1 almost at the end of the trial).
Localized phosphenes were obtained with stimuli of 0.3–0.5 mA (0.5 ms) in Patient 1 and 0.4 mA (1.0 ms) in Patient 2. Two isolated phosphenes or an "8–shaped" phosphene were perceived when stimulated through 2 adjacent channels. Lines of different direction were perceived by stimulating different pairs of channels in Patient 1.
Localized and separate phosphenes were elicited by multi–channel STS system in patients with advanced RP. These results suggest that STS enables pattern recognition and will be a feasible artificial vision system.
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