A very important discovery was made by American scientists, who actually "revived" the eyes of a dead man five hours after his death.
Specifically, scientists revived light-sensing nerve cells in a dead man's eyes and restored communication between them, as part of a series of discoveries that are set to transform brain and vision research.
Billions of neurons in the central nervous system transmit sensory information as electrical signals; in the eye, specialized neurons known as photoreceptors perceive light.
Publishing their research in the journal Nature, a team of researchers from the John A. Moran at the University of Utah and colleagues at Scripps Research describe how they used the retina as a model of the central nervous system to investigate how neurons die - and new methods for regenerating them.
"We were able to awaken photoreceptor cells in the human macula, which is the part of the retina responsible for our central vision and our ability to see fine details and colors," explains Moran Eye Center scientist Fatima Abbas, lead author of the published study.
"In eyes taken up to five hours after the death of an organ donor, these cells responded to bright light, coloured lights, and even very dim flashes of light."
While the initial experiments revived photoreceptors, the cells appeared to have lost their ability to communicate with other retinal cells. The team identified oxygen deprivation as the critical factor leading to this loss of communication.
To overcome the challenge, Scripps Associate Research Professor Anne Hanneken, MD, procured organ donor eyes less than 20 minutes from the time of death, while Moran Eye Center scientist Frans Vinberg, PhD, designed a special transport unit to restore oxygenation and other nutrients to organ donor eyes.
First record of such an achievement
Vinberg also built a device to stimulate the retina and measure the electrical activity of its cells.
Using this approach, the team was able to restore a specific electrical signal seen in living eyes, the "b wave."
This is the first recording of the b wave made from the central retina of postmortem human eyes.
"We were able to get the retinal cells to talk to each other, as they do in the living eye to mediate human vision," says Vinberg."
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