New study brings ray of hope for treating blindness

Amazing are the ways of the brain and it continues to astonish us every now and then. Getting a feel of this recently were neuroscientists when they found out a method to bring back vision in adult mice who were suffering from congenital blindness as per a report in sciencealert.com.

What makes this restoration truly mind blowing is that the mice were suffering from a rare human disorder of the retina known as leber congenital amaurosis. This generally results in blindness or severe visual impairment at birth.

Cause of this is a change in one of the genes concerned with the retina and its ability to sense light. Retinal implants, editing of genes and treatment by drugs were tried to restore vision.

Among these the use of synthetic compounds looked promising for the mutations that involved rod photoreceptors. Located at the back of the eye, rod photoreceptors sense dim light and they convert sensory light into electrical signals enabling the brain to read them.

Children with LCA showed some restoration of vision when they received synthetic retinoid treatment yet scientists wondered if it would work for adults. Elaborating this, the researchers in their paper published in Current Biology wrote: “Although some progress has been made, it still remains unclear the extent to which adult visual circuits can be restored to a fully functional state at the level of the visual cortex upon correction of the retinal defect.”

It is generally believed that the visual system in the brain develops in early life and if the eye is not exercised during this period it results in lifelong deficit in vision. Still, the scientists decided to look at the possibility that this deficit vision may not be wired very rigidly and they gave synthetic retinoids to adult mice who were born with retinal deterioration.

This intervention was successful at partially bringing back the rodents’ light sensitivity and their light-orienting behaviours for 27 days. It was found that following nine days of treatment, a large number of neurons in the visual cortex were being activated by the optic nerve.

Recalling the reaction of the scientists, Sunil Gandhi, a neurobiologist from the University of California, Irvine said: “Frankly, we were blown away by how much the treatment rescued brain circuits involved in vision. Seeing involves more than intact and functioning retinae. It starts in the eye, which sends signals throughout the brain. It’s in the central circuits of the brain where visual perception actually arises.”

The study has given hope to neuroscientists. It suggests that lack of vision in childhood does not necessarily mean it can’t be restored in adulthood.

It is obvious that more studies are required in this field but it does look promising as this benefit could be reaped among older humans too for some types of LCA.

Summing up the study, Gandhi said: “The fact that this treatment works so well in the central visual pathway in adulthood supports a new concept, which is that there is latent potential for vision that is just waiting to be triggered.”

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