Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Surgical Stability and Safety During a 2-Year Clinical Trial.

backgroundTo assess the safety and stability profile of the suprachoroidal retinal prosthesis (ScRP) in participants with retinitis pigmentosa (RP) for 2 years from implantation.

methodsFour participants, with advanced RP and bare-light perception vision were enrolled in a prospective, single arm unmasked interventional clinical trial and unilaterally implanted with a 44-channel ScRP (NCT03406416). Electrical stimulation commenced in the psychophysics laboratory prior to use in local environments. Outcome measures included serious adverse events, adverse events, implant stability and implant functionality to assess the safety and stability profile over 2.0-2.7 years.

resultsSurgical procedures took 204-260 min and were uncomplicated. Postoperative recovery was uneventful. Imaging confirmed the device position under the macula and the absence of retinal trauma. There were no serious adverse events and the adverse events that occurred were mild. All electrodes were functional at surgery completion, and only 3% electrodes lost functionality by study end. There was minor array movement (translational and rotational) within the first 10-15 weeks only. The electrode to retina distance increased as expected with fibrous capsule development, but plateaued in three of four participants within 12 months. Retinal and choroidal thicknesses were consistent with the underlying retinal dystrophic disease.

conclusionsThe ScRP can be safely implanted in the suprachoroidal space and has minimal long-term impacts on the eye, with no SAEs and only slight array movement seen over 2.0-2.7 years. Hence, the findings indicate approach feasibility and further multicentre studies are warranted.