Author: Rita Ehrlich
Co-authors: Peter Stalmans, Inge Joniau, Stanislao Rizzo, Francesco Bandello, Adiel Barak
Abstract
Purpose:The study objective is to demonstrate safety of the NR600 System, and to evaluate the performance of the device in restoring visual activity of daily living in subjects with retinitis pigmentosa and severe visual impairment.
Methods:
Nano Retina initiated a feasibility, first in human study of the NR600 System in severely visually impaired retinitis pigmentosa (RP) patients in Belgium, Italy and Israel. The study is designed as a multi-center, non-randomized, open label, and interventional study. Prior to implantation the patients undergo extensive ophthalmic examinations, including retinal viability status, psychophysical visual examinations and activity of daily living tasks requiring vision, as well as psychological evaluation. About two weeks following unilateral implantation of the device, the implant is activated by an infrared beam projected from the NR Glasses and the optimal stimulation parameters to evoke discrete phosphenes with minimal fading and saturation effects are uniquely set for each patient. With the initial setting of optimal configuration, the patients go through a program of visual training and rehabilitation in the clinic and at their home environment where the visual experience is expected to improve, relying on cortical plasticity. Patients are followed over 18 months post-implantation where the primary safety and performance endpoints are set at 6-months post-optimization of the stimulation parameters.
Results:
Eight RP patients (mean age 66.6±8.5 years, 3 females & 5 males) were implanted with an average follow-up of 10.6 ± 8.6 months. All tolerated the procedure well with fast recovery. The eyes had no evidence of fibrotic reaction and the implant surface as well as the anchoring parts stayed free of tissue debris. No retinal detachment, endophthalmitis or cases of subretinal hemorrhage were observed. Retinal morphology remained without changes or with slight changes in the vicinity of the implant. Two patients experienced possibly procedure/device related SAEs (visual hallucination followed by psychological decompensation, and high IOP that required reintervention to correct a misplaced IOL haptic). Stimulation of the device has resulted in phosphene perception in all eight patients. Threshold settings were typically low, with an average setting of 6.5±2.5µA across all patients (250±70 µS pulse width and 15 ±5 Hz pulse frequency), which supports the concept of ultra-low threshold activation of the retina with a penetrating electrode design. Patients who started the vision rehabilitation program demonstrated significantly improved visual performance in Activity of Daily Living, Orientation & Mobility and Social Interaction tasks when tested with device On vs. device Off and compared to baseline.
Conclusion:
The interim results of the study establish safety of the NR600 prosthesis and positive efficacy for otherwise blind patients. The NR600 can be implanted in human with acceptable long-term safety results.
