In vitro reliability testing and in vivo lifespan estimation of wireless Pixium Vision PRIMA photovoltaic subretinal prostheses suggest prolonged durability and functionality in clinical practice

摘要

Objective. Retinal implants have the potential to restore some sight in patients with retinaldegeneration. The PRIMA implant’s novel design features simpler insertion and no transscleralcabling or extraocular components. This in vitro study investigated PRIMA’s durability under realtime and accelerated conditions and estimated the device’s lifespan in vivo. Approach. Two potentialfailure modes were examined: corrosion and overstimulation. Real-time aging was tested usingimplants immersed in balanced saline solution (BSS) at 37 ◦C, mimicking the intraocularenvironment. Accelerated aging was examined at 77 ◦C (Arrhenius theory). Confirmatory testingof acceleration factor was performed using different temperatures (37 ◦C–87 ◦C) and weakenedimplant coatings. The effect of repeated maximum stimulation was tested using a pulsed infraredlaser (6x acceleration factor). Data were used to estimate device lifespan. Main results. 175 implantswere tested for up to 33 months. No corrosion or water ingress was observed after approximately20 accelerated years. A pixel failure rate of 0.15% was recorded after 10 accelerated years’stimulation. The derived lifespan estimation for the PRIMA implant was 27.0 years with areliability of 90% (95% confidence interval). Significance. The PRIMA implant was found to berobust, with in vitro reliability of at least 10 years. The PRIMA implant shows durability andfunctionality for clinically relevant timespans under similar environmental conditions to thehuman eye. These results require in vivo confirmation.