People deaf from birth develop enhanced sight

People who are deaf from birth develop enhanced sight because of changes to their retinas, scientists have discovered.

The modification gives them better peripheral vision and increases their field of view.

Scientists found that the retinal nerve cells of individuals born deaf, or who went deaf very early in life, are distributed differently from those of hearing adults.

As a result their retinal neurons prioritise the region at the edge of vision, towards the ears.

Previous research suggested that deaf people can see further into the visual periphery than people who hear. However, this was thought to be due to an adaptation in the visual centre of the brain.

The new research, funded by the Royal National Institute for Deaf People, is published in the online journal Public Library of Science ONE.

Scientists scanned the retinas of deaf individuals with a technique called ocular coherence tomography, which works in a similar way to ultrasound using light waves.

Charlotte Codina, medical doctor and a member of the University of Sheffield team, said: “The retina has been highly doubted previously as being able to change to this degree, so these results which show an adaptation to the retina in the deaf really challenge previous thinking.

“This is the first time the retina has been considered as a possibility for the visual advantage in deaf people, so the findings have implications for the way in which we understand the retina to work. Our hope is that as we understand the retina and vision of deaf people better, we can improve visual care for deaf people, the sense which is so profoundly important to them.”

Ralph Holme, head of biomedical research at the RNID, said: “The better peripheral vision experienced by people who are deaf, in comparison to those who hear, has significant benefits for their everyday lives – including the ability to quickly spot hazards at the boundaries of their view.

“This research substantially improves our understanding of how changes in the retina create this advantage, and could help researchers identify ways to further enhance this essential sense for people who are born deaf.” From this month the RNID is changing its name to Action on Hearing Loss.