What are vision prostheses and how do they work?
Vision prostheses, also known as “bionic eyes”, are electronic devices which are implanted into the eye or brain to provide some basic vision to people with severe vision loss. The implants can be put into the eye (on top of, in between, or behind the retina), onto the optic nerve between the eye and brain, or directly into the brain.
In a healthy retina, the photoreceptor cells convert the light entering the eye into electrical impulses, which then travel along the optic nerve to the brain. In inherited retinal diseases, the photoreceptor cells are damaged, but the connecting nerves stay relatively intact. This means that a vision prosthesis can replace the function of the photoreceptor cells, hence returning some basic visual cues.
Whilst all devices have different design features, the similarities are:
- The user will wear a pair of glasses with a small camera embedded into the frame
- The camera will capture images of the person’s surroundings, which are then translated into electrical signals by a small processing unit (around the size of a smart phone)
- The electrical signals are sent to the implant in the eye or brain, which then stimulates the rest of the visual pathway to give perceptions of light (also known as phosphenes)
At this stage of development, the devices provide small spots of light only, which the user can interpret to help them identify objects or people. The vision provided is not like normal sight, but with clever software programming and training, can be very helpful in everyday life.