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Invest Ophthalmol Vis Sci. 2011 Jul 1;52(7):4726-33. doi: 10.1167/iovs.10-6836.

Testing of semichronically implanted retinal prosthesis by suprachoroidal-transretinal stimulation in patients with retinitis pigmentosa.

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Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.



To examine the safety and effectiveness of a retinal prosthesis that is implanted semichronically in two patients with advanced retinitis pigmentosa (RP).


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 perception. Phosphenes were elicited by suprachoroidal-transretinal stimulation (STS). The internal devices of the STS were implanted under the skin on the temporal side of the head, and the 49 electrode-array was implanted in the scleral pocket of one eye. Biphasic electrical pulses (duration, 0.5 ms; frequency, 20 Hz) were delivered through nine active electrodes. The threshold current was determined by currents ≤1 mA. Behavioral tasks were used to determine the functioning of the prosthesis.


The surgery was completed without a retinal detachment and retinal/vitreous hemorrhage. The implanted STS system remained functional for the 4-week test period. Phosphenes were elicited by currents delivered through six electrodes in Patient 1 and through four electrodes in Patient 2. The success of discriminating two bars was better than the chance level in both patients. In Patient 2, the success of a grasping task was better than the chance level, and the success rate of identifying a white bar on a touch panel increased with repeated testing.


Semichronic implantation of a microelectrode-STS system showed that it was safe and remained functional for at least 4 weeks in two patients with advanced RP. ( number, R000002690.).

[Indexed for MEDLINE]

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