From bionic eyes to gene editing, how can we use science to bring back sight?
The human eye is an incredibly complex organ, and researchers continue to actively investigate how the eye functions and, in some cases, why it does not. An estimated 36 million people worldwide are blind, and an additional 217 million people have moderate to severe impairment of their vision. How many of these cases are avoidable? How can science help us reverse visual impairment and even blindness?
Reversing Blindness with Gene Editing
The most common genetic condition affecting vision is known as retinitis pigmentosa. Globally, around 1.5 million children are born with retinitis pigmentosa, a condition which causes the cells on the retina to deteriorate over time. This usually starts with a loss of night vision, followed by tunnel vision, and eventually can end in blindness.
Since retinitis pigmentosa is a genetic condition, it is caused by a genetic mutation. If cells from a healthy retina can be inserted into the eye, they could dominate over the cells with the mutation to either slow or stop the retinal degeneration. However, using cells from someone else’s healthy retina runs the risk of the foreign cells not being accepted by the new host body. Fortunately, new approaches to gene editing like the CRISPR/Cas9 enzyme mean that we can snip out unwanted sections of our own genes.
In a recent study published in the journal Nature, researchers took skin cells from patients with retinitis pigmentosa and used a known technique for turning them into multipurpose cells (called pluripotent stem cells). They then removed the mutation through CRISPR gene editing. When they tested the cells 10 days later, the mutation was still gone. The next steps will be to test whether the cells can be put back into the afflicted retina with positive results.
Researchers are also looking at reprogramming the eye’s own cells to address congenital issues like retinitis pigmentosa and other degenerative diseases like age-related macular degeneration. For example, scientists from the National Eye Institute (part of the National Institutes of Health in the U.S.) recently found that Muller glia, cells that act as connective support between neurons in the eye—or, in other words, retinal glue—could be reprogrammed to function as photoreceptors in the eyes of mice that were born blind, specifically the rods that allow us to see in low light.
Reversing Blindness with Bionic Eyes
Another approach to reversing genetic conditions like retinitis pigmentosa is through replacing the entire affected eye. The Bionics Institute of Australia has created a prototype bionic eye and their first eye transplant was performed in 2012. The female patient reported being able to see flashes of light right away, and scientists are working toward shapes.
In 2015, at a hospital in Colorado, doctors created a bionic eye by implanting a microchip into the retina of a retinitis pigmentosa patient. The microchip coordinates with a pair of glasses which wirelessly transmit video to the chip which stimulates her optic nerve to then send that visual information to her brain. She can see outlines and shadows, but her vision is still far from 20/20.
Researchers are also studying whether bionic eyes could be used to address other causes of vision impairment. In 2015, a British patient got a bionic eye implant to reverse the effects of macular degeneration.