Going deaf and blind happens simultaneously in old age

Editor: Most of us expect that our hearing will decline as we age. And we probably expect our vision to deteriorate, as well. But we may not expect them to happen at the same time! Australian scientists claim that this simultaneous loss is common.

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October 2006

According to Australian scientists, vision and hearing loss happens almost simultaneously in older people. The researchers arrived at this conclusion after examining 1,911 adults living in the Blue Mountains region, west of Sydney, in New South Wales.

The participants had an average age of 70, and among the group, 178 had a visual impairment, categorised as eyesight worse than 20/40, 56 had 'best-corrected' visual impairment, meaning even when using glasses or contact lenses their eyesight was worse than 20/40 and 206 of this combined group also had a hearing problem.

They found the volunteers with restricted eyesight were more likely to suffer hearing impairments and vice-versa.

It is common for people to experience dual sensory impairment or deaf-blindness in their old age and the researchers suspect the underlying causes for these sensory impairments may be the same.

Five years after the original study, between 1997 and 1999, participants, then age 55 to 98, underwent a medical interview along with vision and hearing examinations.

The researchers discovered that, for each line of the eye chart used by ophthalmologists that a participant 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.

Those in the group that suffered hearing loss were 1.5 times more likely to have eyesight problems than those with good hearing.

The researchers also found that both those suffering age-related macular degeneration and cataracts were more likely to suffer hearing loss than those without these disorders.

The authors, from the University of Sydney and the National Acoustics Laboratories, Sydney, said the connection between vision and hearing could be explained by the fact that both are consequences of ageing and suggest common risk factors can predispose people to such sensory impairments.

They believe exposure to oxidative stress, cigarette smoking and atherosclerosis and its risk factors, have been linked respectively to age-related macular degeneration, cataract and hearing loss.

Diabetes is also a common risk factor for cataract and visual and hearing impairments.

Study leader Ee-Munn Chia, M.B.B.S., and colleagues say that irrespective of the cause of sensory impairment, the two impairments were found to significantly affect both physical and mental well being.

They say 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.