People who experience partial vision loss in early childhood find it more difficult to accurately judge the location of a sound than those who lose sight later in life, new research shows.
The randomized controlled clinical trial was the first to compare how people with vision loss before age 10 and those with later onset vision loss judge the distance of sound.
It was led by researchers from Anglia Ruskin University, Cambridge, England and the University of East Anglia, Norwich, England and was published in the June 2024 edition of Optometry and Vision Sciences .
People with vision loss rely heavily on their other senses for path planning, safe navigation, avoiding collisions and general day-to-day living.
The study involved 52 people aged under 33. Each took part in 480 separate trials over an hour and 40 minutes which involved estimating the distance of each sound.
The sounds were emitted from distances ranging from 1.2m to 13.8m away and varied between speech, music, or noise. Participants estimated the distance the sound came from.
The differences in estimations between people with early and late onset vision loss, as well as a fully-sighted control group, was greater for closer distances than for sounds coming from further away.
Compared to the control group, people with early-onset vision loss tended to judge that sounds played from close distances, up to five metres, were actually coming from further away.
Distance judgements were not found to be significantly different between the control group and those with late-onset vision loss.
Lead author Professor Shahina Pardhan, director of the Vision and Eye Research Institute at Anglia Ruskin University said: “These results suggest that people who suffer vision loss at birth or in early childhood are more likely to struggle to accurately judge the distance of close-range sounds.
“This is the first study of its kind and is important when assessing the healthcare needs of people who suffered partial vision loss early in life, such as at birth or in childhood, who tend to be reliant on their other sensory abilities.
“Clearly a difficulty in judging short and medium distance sounds could have safety implications, for example when attempting to cross the road. Hopefully this study will add to evidence that will lead to solutions to improve the lives of people with vision loss across the world.”
The study was co-authored by academics from the University of Cambridge and Sankara Nethralaya Eye Hospital in Chennai, India.
Co-author Dr Andrew Kolarik, of the University of East Anglia’s School of Psychology and Anglia Ruskin University’s Vision and Eye Research Institute, said: “Many studies have shown that fully blind people display measurable changes in their hearing abilities, showing either better or worse performance compared to sighted people depending on the hearing task they are given.
“This study shows that even partial vision losses can lead to changes in hearing abilities, especially if vision is lost early on in life.”
The study was also co-authored by academics from the University of Cambridge and Sankara Nethralaya Eye Hospital in Chennai, India.
