Why the deaf see better than those who can hear

Deaf people have better eyesight than those who can hear, research shows. Scientists discovered that the retinas of people born deaf, or who lost their hearing early in life, developed differently from those in people who can hear. This gave them greater peripheral vision, allowing them to see more and thus increase their awareness of their surroundings and any potential hazards. Researchers at the University of Sheffield discovered that retinal nerve cells are distributed differently in those who are deaf and those who can hear. This makes them prioritise what they can see at their furthest peripheral vision, close to their ears. While previous research had already uncovered the link between deafness and increased peripheral vision, scientists had thought the visual cortex in the brain was responsible, not the retinas. Working on behalf of the Royal National Institute for Deaf People, the Sheffield researchers used ocular coherence tomography to scan the retinas of study participants. Scientists dilated the pupils of the participants just before scanning their retinas. They also measured their visual fields in both eyes to compare with the retina scans. The results, published in the journal PLoS ONE, recorded a significant correlation between changes in retinal distribution in deaf individuals and the effect this had on widening their peripheral vision. Study co-author Dr Charlotte Codina said: ‘Our hope is that as we understand the retina and vision of deaf people better, we can improve visual care for deaf people.’