People who are deaf benefit from better vision due to the fact their retinas develop differently. Research carried out by scientists at the University of Sheffield has shown that the retina of adults who are either born deaf or who become deaf within the first few years of life actually develops differently to that of hearing adults so as to be able to capture more peripheral visual information.
Using retinal imaging data and correlating this with measures of peripheral vision sensitivity, a team led by Dr Charlotte Codina and Dr David Buckley, from the University's Academic Unit of Ophthalmology and Orthoptics, showed that the retinal neurons in deaf people appear to be distributed differently around the retina to enable them to capture more peripheral visual information. Previous research has shown that deaf people are able to see further into the visual periphery than hearing adults, but it was thought that the area responsible for this change was the visual cortex, which is the area of the brain that is particularly dedicated to processing visual information. This research shows for the first time that additional changes appear to be occurring much earlier on in visual processing than the visual cortex, even beginning at the retina.
The team also found an enlarged neuroretinal rim area in the optic nerve which shows that deaf people have more neurons transmitting visual information than hearing.
The findings were collected after the experts used a non-invasive technique called ocular coherence tomography (or OCT) to scan the retina. OCT works in a similar manner to ultrasound however uses light interference as opposed to sound interference. All of the adults involved in the research were either severely or profoundly deaf.
Dr Charlotte Codina said: "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."