Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep.

Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies result in extensive neural and glial remodelling, with survival of excitable retinal neurons that can be electrically stimulated to elicit visual percepts and restore a form of useful vision. The Phoenix99 Bionic Eye is a fully implantable visual prosthesis, designed to stimulate the retina from the suprachoroidal space. In the current study, nine passive devices were implanted in an ovine model from two days to three months. The impact of the intervention and implant stability were assessed using indirect ophthalmoscopy, infrared imaging, and optical coherence tomography to establish the safety profile of the surgery and the device. The biocompatibility of the device was evaluated using histopathological analysis of the tissue surrounding the electrode array, with a focus on the health of the retinal cells required to convey signals to the brain. Appropriate stability of the electrode array was demonstrated, and histological analysis shows that the fibrotic and inflammatory response to the array was mild. Promising evidence of the safety and potential of the Phoenix99 Bionic Eye to restore a sense of vision to the severely visually impaired was obtained.

Safety and biocompatibility of a bionic eye: Imaging, intraocular pressure, and histology data.

The data presented here are related and supplementary data to the research article "Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep" [1]. In Eggenberger et al., nine sheep of the Suffolk (N=2) and Dorper (N=7) breeds were implanted in the left eye with an electrically inactive, suprachoroidal retinal stimulator (Bionic Eye) for durations of up to 100 days. The surgical safety, implant stability and device biocompatibility were assessed. Intraocular pressure measurements, indirect and infrared ophthalmoscopy and optical coherence tomography were performed at fixed time points to evaluate the clinical effects of the surgery and device implantation. Post-mortem eye tissue collection and histology was performed to measure the effects of the intervention at the cellular level. The data, including a comprehensive collection of fundus, infrared, optical coherence tomography and histology images can be used as a reference for comparison with other research, for example, active retinal stimulators. Furthermore, these data can be used to evaluate the suitability of the sheep model, in particular Dorper sheep, for future research.

A method to assess the location and positional stability of supra-choroidal retinal neuroprostheses.

Electrical stimulation of the retina is now firmly established as a means of restoration of rudimentary vision for blindness particularly that caused by retinitis pigmentosa. Of the various approaches, the novel positioning of an ultra-thin stimulating electrode array (SEA) posterior to the choroid has shown promising results. Following their implantation, reliable imaging methods are essential to establish the SEA's location relative to the optic disk and retinal vasculature. Because the opacity of the choroid precludes the use of conventional light-based fundus imaging, we developed an instrument (Wangiscope) that relies on infra-red illumination from LEDs. This instrument generates video from an inexpensive web camera whose optics have been enhanced for wide-angled retinal imaging by adding two plano-concave lenses to the existing lens system. When imaging, the instrument's outer lens, protected by a thin plastic film and methylcellulose gel, contacts the cornea while a probe comprising two 940 nm wavelength LEDS is held against the sclera. This instrument has provided useful retinal images in acute experiments using the Felus catus and also proof of the positional stability over 3 months of SEAs in the Ovis aries.