Ever wondered why people who are born deaf have been gifted with a better vision? Well, that’s probably because their retinas develop differently. According to experts from the University of Sheffield, the retina of adults who are either born deaf or have an onset of deafness within the very first years of life actually develops differently to hearing adults so that it can capture more peripheral visual information.
By means of retinal imaging data and measures of peripheral vision sensitivity, scientists pointed out that, measures of peripheral vision sensitivity are distributed differently around the retina. Hence, deaf people can possibly capture more peripheral visual information. In the course of the investigation, an enlarged neuroretinal rim area was also found in the optic nerve. After examining this area, it was confirmed that deaf people have more neurones transmitting visual information than hearing.
“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,” remarked Dr Charlotte Codina. “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.”
Apart from these tests, a non-invasive technique called ocular coherence tomography (OCT) was also employed for scanning the retina. Through this technique, the depth of retinal architecture including the depth of the neurone layer and dimensions of the components of the optic nerve can be mapped out. The study subjects were either severe/profoundly deaf or hearing and had their pupils dilated just before the retinal scans were taken.
During a separate visit, the participants had their visual fields measured in either eye. The results then compared with the retinal scan information with visual behavior. It then appeared that the alterations in retinal distribution were dramatically associated with the level of advantage individuals were showing in their peripheral vision.
The study is published in the journal PlosONE.