Surgical Approach for Semi-chronic Implantation of Retinal Prosthesis by Suprachoroidal-Transretinal Stimulation (STS) in Patients with Retinitis Pigmentosa

Abstract

Purpose: : We have developed a retinal prosthesis by suprachoroidal-transretinal stimulation (STS) and reported the safety and effectiveness of this approach on acute clinical trials. Now we have developed a wireless device for a semi-chronic trial. In this study we implanted the device in two patients with advanced retinitis pigmentosa (RP) and examined the safety of the surgical procedure.

Methods: : The visual acuity was bare light perception in the left eyes of the patients with RP. The wireless STS device was subcutaneously implanted on the left occipital bone. A scleral pocket of 7x7 mm was created at the lower-temporal to the posterior of the globe and a 49-channel-electrode array (5.7 × 4.6 mm, with each platinum electrode having a diameter of 0.5 mm) was inserted into the pocket. The cables were then secured with sutures on sclera around the eye. A platinum return electrode was inserted into the vitreous cavity through the pars plana at the upper-nasal area. Five and seven weeks after implantation, the devise, wire and electrodes array were removed. Approval from the Institutional Review Board Committee and informed consent were obtained for these cases.

Results: : The surgery was performed without serious complications such as infection, epilepsy, endophthalmitis, retinal detachment or retinal and choroidal bleeding. The surgical time was approximately 6 hours. Eye movement was slightly restricted in several directions during implantation for the first case. Conjunctival suture was performed at a more posterior position than usual for the second case and eye movement was then normal during implantation. After the removal of the system, the eye movements of both cases were normal. Visual acuity was light perception after the removal of the device.

Conclusions: : The wireless device was developed for a semi-chronic implantation of the retinal prosthesis by STS. No serious complications occurred during and after the surgery, suggesting that this procedure is safe enough to perform a chronic trial.

Clinical Trial: : UMIN, UMIN000002208

Keywords: retina • clinical (human) or epidemiologic studies: systems/equipment/techniques