New gene therapy could rewire the eye to help blind people see

By making normal nerve cells into light-sensing ones, scientists might be able to give some patients their sight back

Dr Ian Crozier caught the deadly Ebola virus in September last year while he was working in West Africa during the latest outbreak (Rex images)

Scientists might be able to change the cells in blind people’s eyes, giving them the power to see again.

If the rods and cones that make up the photoreceptors of the eye fail because of injury or illness, then people can lose their sight entirely. Now, scientists hope that they can use gene therapy to transform nerves in the eye to replace those lost photoreceptors.

The technique has been developed by Zhuo-Hua Pan of Wayne State University in Detroit. It is part of a new field called optogenetics, which uses molecules from algae or other microorganisms that respond to light, or creates molecules to do so, and put them into nerve cells to transform them so that they can receive light.

As well as helping blind people see, the new field has also given insight into how the brain works. It can even be used to alter memories.

Now the scientists hope that they can use the technique to restore the sight of blind people — a technique that has already worked on animals. Studies in humans could begin next year.

Optogenetics is a form of gene therapy, and works by changing the makeup of the damaged cells. But since it only converts — rather than edits — genes, it is not likely to cause the same kind of ethical and practical problems that blight work on other forms of gene therapy.

When the new genes are placed into cells, they will produce working copies of proteins to help it get back working again. The same technique has been used to help children with fault immune systems and has already restored the sight of people with a specific form of blindness.

About 200,000 people in the US have inherited diseases that cause problems for the photoreceptors in their eye. When those cones and rods are gone, there’s usually no way of restoring them.

But the new approach gets around relying on those photoreceptors. Instead it focuses on the ganglion cells behind them, which usually work to take the information between the rods and cells and the brain.

But the scientists hope that they can rewire those cells so that they become light-sensitive, by inserting the right molecules and shining light at them. The light wakes up the right proteins, allowing messages to flow through and then bringing out the same behaviour in cells around them.