Abstract
Loss of photoreceptors in atrophic age-related macular degeneration results in severe visual impairment, although some peripheral vision is retained. To restore central vision without compromising the residual peripheral field, we developed a wireless photovoltaic retinal implant (PRIMA; Pixium Vision, Paris, France) in which pixels convert images projected from video glasses using near-infrared light into electric current to stimulate the nearby inner retinal neurons. We carried out a first-in-human clinical trial to test the safety and efficacy of the prosthesis in patients with geographic atrophy (ClinicalTrials.gov identifier, NCT03333954). Five patients with geographic atrophy zone of at least 3 optic disc diameters, no foveal light perception, and best-corrected visual acuity of 20/400 to 20/1000 in the worse-seeing study eye. The 2-mm wide, 30-μm thick chip, containing 378 pixels (each 100 μm in diameter), was implanted subretinally in the area of atrophy (absolute scotoma). Anatomic outcomes were assessed with fundus photography and OCT for up to 12 months of follow-up. Prosthetic vision was assessed by mapping light perception, bar orientation, letter recognition, and Landolt C acuity. In all patients, the prosthesis was implanted successfully under the macula, although in 2 patients, it was implanted in unintended locations: within the choroid and off center by 2 mm. All 5 patients could perceive white-yellow prosthetic visual patterns with adjustable brightness in the previous scotomata. The 3 with optimal placement of the implant demonstrated prosthetic acuity of 20/460 to 20/550, and the patient with the off-center implant demonstrated 20/800 acuity. Residual natural acuity did not decrease after implantation in any patient. Implantation of the PRIMA did not decrease the residual natural acuity, and it restored visual sensitivity in the former scotoma in each of the 5 patients. In 3 patients with the proper placement of the chip, prosthetic visual acuity was only 10% to 30% less than the level expected from the pixel pitch (20/420). Therefore, the use of optical or electronic magnification in the glasses as well as smaller pixels in future implants may improve visual acuity even further.
Highlights
Prosthetic vision was assessed by mapping light perception, bar orientation, letter recognition, and Landolt C acuity
In 3 patients with the proper placement of the chip, prosthetic visual acuity was only 10% to 30% less than the level expected from the pixel pitch (20/420)
Study participants were older than 60 years and had advanced dry Age-related macular degeneration (AMD) with an atrophic zone of at least 3 optic disc diameters and best-corrected visual acuity of 20/400 or worse in the worse-seeing study eye; no foveal light perception, but visual perception in the periphery, with preferred retinal locus determined by microperimetry; absence of photoreceptors and presence of the inner retina in the atrophic area as confirmed by OCT; and absence of choroidal neovascularization verified by retinal angiography
Summary
The 2-mm wide, 30-mm thick chip, containing 378 pixels (each 100 mm in diameter), was implanted subretinally in the area of atrophy (absolute scotoma). Prosthetic vision was assessed by mapping light perception, bar orientation, letter recognition, and Landolt C acuity. The aim of this first-in-human feasibility study of the PRIMA implant (ClinicalTrials.gov identifier, NCT03333954) was to test safety and functionality of this device in 5 patients with AMD. Study participants were older than 60 years and had advanced dry AMD with an atrophic zone of at least 3 optic disc diameters and best-corrected visual acuity of 20/400 or worse in the worse-seeing study eye; no foveal light perception (absolute scotoma), but visual perception in the periphery, with preferred retinal locus determined by microperimetry; absence of photoreceptors and presence of the inner retina in the atrophic area as confirmed by OCT; and absence of choroidal neovascularization verified by retinal angiography.
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