Light in the Dark
New visual prostheses are intended to replace missing or defective photoreceptors in the retina - and give blind people some sight again.
Since he was diagnosed with retinitis pigmentosa at the age of six, Peter Böhm has lived with the knowledge that his eyesight will steadily decrease. The hereditary disease, in which light-sensitive cells in the retina die off, affects about one in 4000 people. It usually causes significant visual impairments such as night blindness, increased sensitivity to glare and tunnel vision. Some of those affected even become completely blind. In 2014, Böhm himself was no longer able to see with his left eye at all and with his right only to a very limited extent.
That year he underwent an operation intended to partially restore his vision: he had a retinal implant placed in the retina of his left eye. Such visual prostheses consist of chips, each with a few hundred electrodes or light-sensitive photodiodes. They translate light into tiny electrical impulses, which they emit into their environment. Nerve cells in the retina register this signal and transmit it to the brain. The impression of "phosphenes", i.e. single-colored points of light, is then created in the cortex.
After the operation, Böhm watched fireworks at a folk festival. In a 2017 TEDx Talk, he described the experience…
