Abstract
Purpose :
We have reported the feasibility of 9-channel STS retinal prosthesis in subacute clinical trial (Fujikado, IOVS 2011). In this study, we report the one-year outcomes of clinical trials (interventional case series) to evaluate the safety and effectiveness of a 49-channel STS retinal prosthesis.
Methods :
Three patients with advanced retinitis pigmentosa (RP) with vision ≤HM were studied. A 49 channel STS retinal prosthesis system was implanted. The stability of the prosthesis, side-effects, and the efficacy of artificial vision were investigated during 1 year. Square localization tests, walking tests, and table tests were performed to assess the visual functions.
Results :
The electrode array was implanted in a scleral pocket located under the parafoveal inferotemporal retinal area. The scleral incision was made 14 mm (Pt1), 16 mm (Pt2), and 18 mm (Pt3) from the sclero-corneal limbus. Irido-cyclitis was observed in Patients 2 and 3 at 2 and 5 months after the implantation. The irido-cyclitis was successfully treated with topical medications. The implanted devices were still functioning during the follow-up period in all cases. The number of electrodes which elicited phosphenes with a current less than 1 mA and without evoking somatosensory sensation was 36, 34, and 18. The results of square localization test (P<0.05) and table tests (P<0.05) were significantly better with the prosthesis turned ON than OFF in Patient 3. The deviation of the walking test were smaller with the prosthesis turned ON than OFF in Patients 2 (P<0.01) and 3 (P<0.01).
Conclusions :
The 49-channel STS-Japan retinal prosthesis was able to elicit phosphenes in all 3 patients with advanced retinitis pigmentosa without major complications, and the device was functional for at least 1-year. Greater improvements of visual tasks were observed in patients in which the electrode array was implanted closer to the fovea centralis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.