New insight into cataracts
New insight into cataracts In a world-first, Brisbane scientists have discovered that the most common form of cataracts - the world's leading cause of blindness - is caused by exposure to ultra-violet radiation.
Nuclear cataracts are the most common cataract and occur in the centre of the eye lens. Previous international studies showed that UV was a risk for cortical cataracts which occur outside the eye lens and are less common. A cataract is a clouding of the natural lens of the eye - the part of the eye responsible for focusing light and producing clear, sharp images.
Cataracts are the major cause of blindness around the world. Of the world's 40 to 45 million blind people, approximately half are blind from cataracts and of those, 80 per cent have nuclear cataracts.
As populations age, the number of blind people is expected to double by the year 2025.
In Australia more than 120,000 cataract operations are performed every year.
Until now, people have believed that cataracts were a "natural" part of ageing.
"Our study indicates that cataracts may not be natural, but that they are preventable," Queensland Institute of Medical Research Associate Professor David Purdie (pictured right) said.
Dr Purdie said the QIMR study offered new evidence to support a link between sun exposure and nuclear cataracts.
He said cataract risk was highest among people who had high sun exposure at younger ages.
"It is plausible that previous studies have failed to identify the link between sun exposure and nuclear cataracts because they did not specifically analyse exposure in the early years of life," Dr Purdie said.
"These results suggest that the majority of ultraviolet-induced lens damage occurs before 30 years of age.
"People who had high sun exposure in their 20s but low in subsequent decades had consistently higher risks than those with low exposure between 20 and 29.
"The study also identified that wearing sunglasses with UV protection early in life gave greater protection from cataracts than wearing sunglasses at older ages.
"There is potentially an easy solution to a very serious problem around the world - wear sunglasses with UV protection. The next step is education."
Dr Purdie said the study had significant implications not only in Australia and Queensland where an outdoor lifestyle was common, but also internationally.
"In developing countries, cataracts are not treated and people are going blind. If we can prevent cataracts in the first place, that's a unique opportunity we have.
"Studies such as this are vital in alerting people to the causes of cataracts so they can take preventive practices and avoid disease later in life," Dr Purdie said.
The latest discovery forms part of the Nambour Trial of Skin Cancer Prevention study at the QIMR, which is internationally recognised as one of the largest trials of sunscreen use and its effect on skin cancer.
The QIMR study was published in the United States Journal called Epidemiology, which is read internationally by public health professionals.
Contact:
Christine Borthwick, QIMR
christiB@qimr.edu.au
telephone (07) 3362 0291