One-Year Outcome of 49-Channel Suprachoroidal-Transretinal Stimulation Prosthesis in Patients With Advanced Retinitis Pigmentosa.
OBJECTIVE
To determine the feasibility of a 49-channel suprachoroidal-transretinal stimulation (STS) retinal prosthesis that was implanted for 1 year.


METHODS
Three patients with advanced retinitis pigmentosa (RP) and with less than or equal to hand motion (HM) vision were studied. A 49-channel STS system was implanted in a scleral pocket, and the stability of the prosthesis, adverse events, and its efficacy were investigated.


RESULTS
The electrode array was implanted in a scleral pocket located under the parafoveal area through a scleral incision at 14 mm in patient (Pt) 1, 16 mm in Pt 2, and 18 mm in Pt 3 from the sclerocorneal limbus. No complications occurred during surgery in all cases. During the follow-up period, iridocyclitis developed in Pt 2 and Pt 3, which was successfully treated with topical medications. The implanted devices continued functioning and elicited phosphenes in all cases. The results of localization tests (P < 0.05) and table tests (P < 0.05) were significantly better with the prosthesis turned on than turned off in Pt 3. The deviations of the walking tests were smaller with the prosthesis turned on than off in Pt 2 and Pt 3 at multiple times after the implantation.


CONCLUSIONS
The 49-channel STS retinal prosthesis was able to elicit phosphenes in all patients with advanced RP for the entire 1-year experimental period without major complications. Better results on visual tasks were found in the eyes in which the electrode array was implanted closer to the fovea centralis.
Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan 2Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Takashi
T
Fujikado
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Motohiro
M
Kamei
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Hirokazu
H
Sakaguchi
Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan 3Nidek Co., Gamagori, Aichi, Japan.
Hiroyuki
H
Kanda
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Takao
T
Endo
Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.
Masakazu
M
Hirota
Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan 2Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Takeshi
T
Morimoto
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Kentaro
K
Nishida
Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka, Japan.
Haruhiko
H
Kishima
Nidek Co., Gamagori, Aichi, Japan.
Yasuo
Y
Terasawa
Nidek Co., Gamagori, Aichi, Japan.
Koji
K
Oosawa
Nidek Co., Gamagori, Aichi, Japan.
Motoki
M
Ozawa
Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
Kohji
K
Nishida
D000328:Adult; D000368:Aged; D002829:Choroid / Q000503:physiopathology; D004558:Electric Stimulation / Q000379:methods*; D005074:Evoked Potentials, Visual; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D012160:Retina / Q000503:physiopathology; D012174:Retinitis Pigmentosa / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity; D057488:Visual Prosthesis