PRIMA Retinal Implant Restores Central Vision in Geographic Atrophy Patients, Achieving 81% Response Rate
核心洞察
The PRIMA subretinal implant demonstrated clinically meaningful vision improvement in 81% of patients with geographic atrophy (搜索) secondary to age-related macular degeneration (搜索) at 12 months.
Patients achieved an average improvement of 23 letters on visual acuity tests, with the best performers gaining 59 letters, enabling reading and writing tasks.
The wireless 2×2 mm device bypasses damaged photoreceptors (搜索) by stimulating bipolar cells (搜索) through 378 photovoltaic pixels activated by near-infrared light.
The PRIMA photovoltaic retinal stimulation system has demonstrated the ability to restore central vision in patients with geographic atrophy (搜索) (GA) secondary to age-related macular degeneration (搜索), marking what researchers describe as the first retinal prosthetic device treatment to restore functional central vision in this patient population. Results from the PRIMAvera study, published in the New England Journal of Medicine, showed that 81% of patients achieved clinically meaningful vision improvement at 12 months post-implantation.
Revolutionary Approach to Vision Restoration
The PRIMA system (搜索) represents a paradigm shift in GA treatment, moving beyond current therapeutic approaches that focus on slowing disease progression. While recently approved therapies like pegcetacoplan injection (Syfovre; Apellis Pharmaceuticals) and avacincaptad pegol intravitreal solution (Izervay; Astellas Pharma Inc) work by inhibiting the complement cascade (搜索), no approved therapies have previously led to meaningful vision improvement in GA patients.
Frank G. Holz, MD, FEBO, FARVO, chair of the Department of Ophthalmology at the University of Bonn, Germany, and lead researcher, explained that the device addresses the fundamental problem in GA: "It sits where all photoreceptors (搜索) are gone. But fortunately, the other neurons are still there."
Device Technology and Mechanism
The PRIMA implant is a wireless crystalline silicon array measuring 2×2 mm and 30 μm thick, comprising 378 photovoltaic pixels each 100 μm in width. The system includes specialized glasses equipped with a camera that captures images and projects them onto the implant using near-infrared light at 880 nm wavelength. The 378 pixels convert this near-infrared light into electrical pulses that stimulate retinal bipolar cells (搜索), bypassing the damaged photoreceptors (搜索) and restoring visual information flow to the brain.
Clinical Trial Results
The PRIMAvera study (NCT04676854) was an open-label, multicenter, prospective, single-group, baseline-controlled clinical trial conducted across 17 clinical sites in five European countries. Thirty-eight patients with foveal-involving GA and visual acuity of 20/320 or worse underwent PRIMA implantation, with 32 completing the 12-month evaluation.
The primary endpoint of clinically meaningful visual acuity improvement, defined as 0.2 logMAR or greater improvement from baseline, was achieved in 26 patients (81%; 95% CI, 64-93; P < .001). Using multiple imputation to account for missing data from six patients, researchers estimated that 80% (95% CI, 66-94; P < .001) of all participants would have achieved clinically meaningful improvement at 12 months.
The mean improvement at 12 months was 23 letters, with the best-performing patients achieving gains of 59 letters. Patients reported practical benefits, including the ability to read text and recognize numbers in real-world settings such as train stations.
Safety Profile and Adverse Events
Twenty-six serious adverse events occurred in 19 patients, all attributed to the implantation procedure alone or the procedure combined with the implant, but none to the implant itself. Eighty-one percent of these events occurred within two months post-operatively, with 95% resolving within two months of onset. Twenty-two events were classified as mild or moderate, while four severe events included full-thickness macular hole, ocular hypertension, retinal detachment, and proliferative vitreoretinopathy.
The wireless design eliminates the need for external cables, significantly improving the safety profile compared to previous generations of bionic vision implants. Long-term follow-up extending to three years showed no biocompatibility issues, fibrosis, or inflammation.
Patient Experience and Rehabilitation
Learning to use the PRIMA implant requires a rehabilitative process spanning several months. Patients gradually learn to recognize letter sequences and words while integrating their remaining peripheral vision with the artificial central vision provided by the device. Video documentation showed patients reading text slowly but precisely, a task impossible without the device.
Future Implications
The researchers noted that the wireless design allows for potential replacement with higher-resolution next-generation implants or implantation of multiple arrays in a tiled pattern within the atrophic area with minimal incision requirements. This technology opens the door for future devices that may offer expanded fields of view and enhanced visual restoration capabilities.
The study represents a significant breakthrough in treating advanced GA, offering hope for vision restoration in patients who have exhausted other therapeutic options. As Holz concluded, "The PRIMA subretinal implant restored meaningful central vision in persons with GA due to AMD, thus enabling the performance of visual tasks such as reading and writing."