Just five days of training can make the visual acuity of older adults equivalent to that of adults in their 20s, according to a surprising study conducted by researchers from the University of California, Riverside, and Brown University and published in the journal Psychological Science.
The focused visual training regimen improved older adults’ sensitivity to contrast, and their ability to see things close up.
“Our research indicates that the visual system of older adults maintains a high degree of plasticity and demonstrates that training methods can be used to improve visual function,” researcher G. John Andersen said.
Earliest form of vision loss
Loss of vision and visual processing are common effects of aging, even in people without any eye disease. Indeed, studies have shown that loss of visual contrast (and a corresponding difficulty viewing grainy or poorly defined images) is not caused by eye health but is a result of changes in brain function.
“This is important because sensitivity to subtle changes in contrast is a significant issue for older individuals, and age-related declines in contrast sensitivity can be critical for many real-life tasks such as driving at night,” researcher Denton J. DeLoss said.
A loss of contrast sensitivity is usually one of the first age-related vision changes to manifest. In addition to making driving more dangerous, it can also significantly increase the risk of falls.
Yet, because loss of contrast sensitivity is caused by brain changes, the researchers wondered if those changes might not be reversible. Therefore, they recruited 16 young adults (average age 22) and 16 older adults (average age 71), all screened to be free of eye disease or cognitive decline. Participants visited the lab for a 1.5-hour visual training session daily for seven days. The sessions consisted of looking at striped images and deciding which way they had been rotated. The researchers adjusted the contrast of the images over time, pushing the graininess to the limit of what each participant had been able to distinguish in prior tests. Participants completed 750 trials per day, for a total of 3,750 tests in a week.
While the tests were taking place, the researchers also used sophisticated equipment to measure the dilation of the participants’ eyes. This allowed them to rule out the possibility that vision was improving due to increased pupil dilation.
Dramatic improvement in days
The researchers found that, while younger adults had better contrast sensitivity at the beginning of the study, by the end the sensitivity of the older adults had improved to match that of the younger ones. Pupil dilation contributed almost nothing to this improvement — nearly all the improvement came from enhanced brain function.
Surprisingly, the visual acuity of both younger and older adults also improved dramatically during the study, in just five days. Older adults improved in their ability to see nearby objects, while younger adults improved their ability to see distant ones.
The results were so surprising that the researchers doubled the number of study participants to make sure that they weren’t a fluke. The results held up.
“We did not expect such significant changes in acuity with only five days of training,” DeLoss said. “We found an average improvement of roughly three letters using a standard acuity test. Five letters would be equivalent to moving down a line on a standard chart-based vision test that you typically see at an optometrist’s office.”
The researchers are planning to conduct further studies to see if the benefits from the training can also improve performance of real-world tasks, such as driving.
“We hope that we can continue this line of research in the future and that it will eventually allow us to create interventions that can be used by the general public to counteract age-related declines in vision,” DeLoss said.