Australian researchers claim that there may be a strong correlation between visual impairment and a loss of hearing in older adults.

A new research conducted by University of Sydney scientists found that adults who experience vision loss as they age are more likely to have hearing loss and vice versa.

The study, involved 1,911 adults with an average age of 69.8, whose hearing and visual abilities were examined five years after being originally evaluated between 1997 and 1999.

The researchers discovered that, for each line of the eye chart used by ophthalmologists that a volunteer could not see, there was an 18% (for the visually impaired) and 13% (for the best-corrected visually impaired) increase in the likelihood of hearing loss.

The two most common causes of age-related vision loss, cataracts and age-related macular degeneration, were independently associated with hearing loss.

According to the report, loss of both vision and hearing may be a regular part of aging and it may explain why older adults often have the two conditions. In addition, common risk factors could predispose older adults to both conditions.

"Each condition has been postulated to result from somewhat similar genetic,environmental and lifestyle factors. Exposure to oxidative stress [when cells receive too much oxygen], cigarette smoking and atherosclerosis [hardening of the arteries] and its risk factors have been linked respectively to age-related macular degeneration, cataract and hearing loss. Another common risk factor for cataract and visual and hearing impairments is diabetes," the authors wrote.

"Irrespective of the cause of sensory impairment, these two impairments were found to have a cumulative effect on function and well-being, significantly affecting both physical and mental domains. Further studies are needed to understand the relationship between visual and hearing impairments in older persons and to determine whether intervention to improve these impairments could delay biologic aging," they conclude.