French researchers study the capacity of artificial eyes to restore sight in AMD patients

Subretinal implants could help patients suffering from age-related macular degeneration (AMD), an eye disease which is the most common cause of blindness in people aged over 50.

Scientists at the French National Institute of Health and Medical Research (inserm) have developed an ocular implant to replicate the role of the retina's light-sensitive cells (photoreceptors) to help restore the sight of patients suffering from age-related macular degeneration (AMD). The results of initial studies on animals and AMD patients are encouraging.  

A team from Institut de la Vision (Inserm-CNRS- Sorbonne Université) led by Inserm researcher Serge Picaud has shown that a device could be used to induce high-resolution visual perception. The results of their research have been published by the review Nature Biomedical Engineering.

Developed by the company Pixium Vision, the artificial retina project aims to help patients who have age-related macular degeneration (AMD), which is the main cause of blindness in over-50s, and those suffering from retinitis pigmentosa, a pathology that can also progressively lead to blindness.

The device consists of implants fixed under the retina and composed of electrodes to replace the photoreceptor cells of the retina, which transform light signals into electrical signals that are then transmitted to the brain.

To date, two models of artificial retina have been developed and put on the market: Argus II (Second sight, USA) and Retina Implant (AG, Germany). "Nevertheless, these companies are gradually withdrawing from the market, particularly because the results seen in patients have been insufficient for targeting the device at those with AMD. The patients managed to see light signals but those able to distinguish letters were very much in the minority," explains Serge Picaud.

Sight of five AMD patients restored by the device

The objective of the team of French researchers was to design a new visual prosthesis based on the principle of the artificial retina which would be a simpler device in the form of a connected implant designed to improve the resolution of images perceived by the eye projected by infrared stimulation.

Its effectiveness has been tested in the laboratory on non-human primates. The experiment showed that each pixel activates different cells in the retina. This selectivity results in a very high resolution. 

These encouraging results led to the device being tested on five French patients suffering from AMD. "Initial results show a gradual restoration of central vision. They are able to perceive light signals and some can even identify sequences of letters, with growing rapidity over time," point out the researchers.

"The objective now is to conduct a Phase 3 trial in a larger group of patients with AMD. If the artificial retina works for them, there is no reason why it should not work in patients with retinitis pigmentosa -- a disease also related to photoreceptor degeneration," concludes Serge Picaud.