The semichronic suprachoroid transscleral (STS) prosthesis is developed by Fujikado et al. in Japan. In 2011 and 2016, this retinal prosthesis was reported to be able to elicit phosphenes in all five patients with advanced RP without major complications.

Suprachoroidal-Transretinal Stimulation (STS) internal device was 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 last update on the device’s information was in 2018 under the paper titled “Light localization with low-contrast targets in a patient implanted with a suprachoroidal–transretinal stimulation retinal prosthesis.”

Device Specifications

• Number of electrodes: 49
• Electrode layout: 7x7
• Electrode diameter: 500 μm
• Electrode pitch: 700 μm
• Image processor location: in glasses