Solar panels in the eyes: reality or distant future?

Implanting tiny solar cells in people's eyes might sound like a futuristic idea, but it's what Australian scientists are exploring. This advanced technology could greatly help those with eye diseases.

Implanting tiny solar cells into people's eyeballs may seem like science fiction, but that's exactly what a group of Australian scientists are working on. The next-generation technology could significantly improve the quality of life for people with incurable eye diseases. Neuroprostheses are devices that interact with the nervous system to restore lost functions. One example is the cochlear implant, which helps people hear better by stimulating the auditory nerve.

Now, researchers at the University of New South Wales (UNSW) are investigating if similar technology can restore vision in those with damaged photoreceptors - cells in the retina that convert light into electrical signals sent to the brain. While camera sensors offer excellent image quality, they need power. But implanting batteries in the eye isn't feasible. Instead, solar cells, which convert light into electricity, offer a solution.

"People with certain diseases like retinitis pigmentosa and age-related macular degeneration slowly lose their eyesight as photoreceptors at the center of the eye degenerate," says Dr Udo Römer, a specialist in photovoltaics, known more commonly as solar panel technology. "It has long been thought that biomedical implants in the retina could stand in for the damaged photoreceptors. One way to do it is to use electrodes to create voltage pulse that may enable people to see a tiny spot."

When light enters the eye, photoreceptors convert it into electrical signals, which travel to the brain via the optic nerve, enabling sight. RP and AMD cause these photoreceptors to deteriorate, leading to vision loss.

Römer's interest in using solar cells for medical purposes was sparked by a conversation with a biomedical student. Initially skeptical, he realized that stacking solar cells could provide the necessary voltage to stimulate neurons in the eye. Silicon solar cells are common, but stacking them is challenging. Römer's team is exploring materials like gallium arsenide and gallium indium phosphide, which offer better flexibility for this purpose.

Funded by the Australian Research Council, their research is progressing well. Trials have shown promising results, but inserting wires into the eye poses challenges. An alternative approach involves attaching a solar panel to the eye's surface. While still in the proof-of-concept stage, the technology shows immense potential. Future versions aim for smaller pixels and higher resolution, paving the way for human trials.

However, there are limitations. The device currently only works when exposed to a laser and provides black-and-white images with low resolution. Additionally, sunlight may not provide enough power for the solar cells, necessitating smart glasses to amplify the signal. Römer emphasizes that the device is solely for medical use, not for enhancing abilities artificially.