gms | German Medical Science

Objective: To assess the passive, in vivo performance of a visual prosthesis comprising 98 stimulation electrodes on an array placed within the supra-choroidal space, a small hermetic capsule containing a single microchip and monopolar return electrode fixed to the globe, and a flexible lead wire leading to a hermetically-sealed telemetry implant for the transmission of data and power.

Materials and Methods: Ovis aries (sheep, N=4) were implanted for a period of not less than 90 days with fully-implantable, passive systems. System performance in terms of device stability, macroscopic tissue responses, and material robustness was assessed through a number of means including X-ray, indirect ophthalmoscopy and infra-red imaging, micro-CT, and visual inspection of the surgical sites through dissection under magnification.

Results: With the exception of one event where the flexible lead-wire became dislodged from the orbital margin, all devices remained stable in their intended position, showed no signs of adverse tissue responses, and maintained their material integrity through implantation, testing, and explant phases.

Discussion: The Phoenix99 supra-choroidal implant appears to be appropriately designed and manufactured with a robust and reliable surgical implantation approach. Histological analysis outcomes will determine if the devices should now proceed to fully active systems for the assessment of the effects of stimulation on the retina.

Acknowledgment: This work was supported by UNSW Australia and the Australian Research Council’s Special Research Initiative in Bionic Vision Research and Technology granted to Bionic Vision Australia.