Australian researchers have helped combine studies of more than 170,000 people to find “conclusive evidence” that regular exercise reduces the risk of age-related cataracts.
In a recent paper published in the International Journal of Ophthalmology, researchers from China’s Xi’an Jiaotong University and the University of South Australia (UniSA) also suggest that the cataract risk could decrease 2% for every hour of physical activity.
They assessed data from six different studies involving more than 19,000 cases looking at how exercise reduces oxidative damage in the eye
The meta-analysis found a 10% reduction in age-related cataracts (ARC) among people who engaged in regular physical activity such as walking and cycling.
UniSA epidemiologist Dr Ming Li said physical activity reduces oxidative stress in the eye by inhibiting lipid degradation which results in cell damage.
“We know that exercise increases antioxidant enzyme activity which has all sorts of benefits, including limiting infections and inflammation in the eye,” she said.
Previous studies have shown that long-term physical activity also elevates HDL (high-density lipoprotein), otherwise known as the ‘good cholesterol’, which may carry more antioxidants from plasma to the lens to prevent oxidative damage.
Exercise also improves insulin resistance and lipid profiles, both of which have been associated with an increased risk of ARC.
“Age-related cataracts are one of the most common causes of vision impairment and blindness in the world and although surgery is an effective option to recover vision, it is very costly,” Li said.
“The lens is highly susceptible to oxidative damage because of its high concentration of polyunsaturated fatty acid and its specific biological function. Although we don’t completely understand the mechanisms underlying ARC, we do know that ageing and oxidative damage play a crucial role in the development of the disease.”
The researchers found the risk of cataract could decrease by 2% for every six metabolic equivalents per day of physical activity – approximately equivalent to jogging or cycling for an hour.
However, with 23% of adults reportedly inactive and a series of physical activity related diseases, including the high incidence and huge burden of ARC, encouraging physical activities such as walking, cycling in a supportive physical environment, could bring a great public health significance to prevent ARC, the researchers noted.
“These findings will hopefully encourage older people to start exercising on a regular basis,” Li said.