Researchers at Okayama University have devised a thin photoelectric film which can stimulate degenerated retinal tissues of the eye and rejuvenate it. The team, led by Dr. Matsuo Toshihiko at Okayama University, has developed OUReP, a photoelectric dye-infused in a thin film generates current when exposed to light.
OUReP is made by sandwiching a thin sheet of the polymer polyethylene between two aluminum plates. Heating the plates melts the polymer, then applying pressure turns it into a fine polyethylene film. The film then undergoes a chemical reaction that couples it to a photoelectric dye.
Researchers initially measured the electric potential-generated by the film when it was exposed to a flashing light. As expected, waves of electric signals were observed on the film surface when light hit the film. To test the ability of the film to stimulated nervous tissue, the researchers used retinal tissues of rats with retinal dystrophy, a degenerative disorder.
As a control, they exposed retinal tissues from healthy to light and detected electrical signals using a multielectrode array. A similar set was built using dystrophic retinal tissue, but no signals were measured when it was exposed to flashing light. A photoelectric dye-coupled film was then placed on top of the dystrophic tissues and the flashing light was able to induce electric signals in response. A control film, without the photoelectric dye induced no electric signals in the diseased tissues.
To measure these electric signals more precisely, a nylon mesh was used to keep the dystrophic tissues and the multielectrode array detector in closer contact. This proximity revealed background electric impulses of weak amplitude with the dystrophic retinal tissues alone. In the background of weak amplitude of these signals, light induced remarkable action potential spikes in the dystrophic retinal tissues, in the presence of the photoelectric dye-coupled film. The photoelectric dye-coupled film was thus instrumental in boosting electrical impulses within the degenerated retina.
"The study showed that the photoelectric dye-coupled polyethylene film elicits electrical activity and action potential spikes in degenerative retina," conclude the researchers. Retinitis pigmentosa is one condition in which photoreceptors in the retina tissue slowly die, leading to blindness. The OUReP thin-film could replace the lost photosensitivity of these degraded cells. Implanting the device and testing visual enhancement in animals have given researchers further insights and hopes their invention could cure or at least delay blindness in some patients.