A possible cause and a potential treatment for one of the most common forms of blindness – age-related macular degeneration - have been identified for the first time in a new study by an international team of vision researchers.
The study published in the leading journal Nature has shown that a key enzyme, known as DICER1, is greatly reduced in the eyes of people with the most common "dry" form of the disease – known as Geographic Atrophy (GA).
The team, led by Hiroki Kaneko in the lab of Professor Jay Ambati at the University of Kentucky, was then able to show through a series of experiments that artificially reducing DICER1 levels resulted in the same kind of degeneration of retinal cells in specially bred mice as seen in human GA.
The researchers found evidence that DICER1 plays a key role in digesting a fragment of genetic material - Alu RNA - within the retinal cells: the researchers suggest that a build-up of Alu RNA in the retina may be what causes the disease. It is the first time that Alu RNA – which is found widely in the primate genome only - has been suggested as a cause of diseases.
In turn, this opens up possible new routes for treatment by boosting DICER1 levels in the eyes or by reducing Alu RNA levels.
The team included Dr Michele Madigan, of the UNSW School of Optometry and Vision Science, whose role included providing access to eyes with AMD in association with the Lions NSW Eye Bank at Sydney Eye Hospital. Dr Madigan is also associated with the Save Sight Institute, University of Sydney and collaborates with Professor Jan Provis at ANU Medical School.
"Age-related macular degeneration is common, affecting one in seven people over the age of 50 in Australia and is a leading cause of blindness in our ageing population," notes Dr Madigan.
"This research is exciting not only because it gives us fundamental new insights into a condition that is not well understood, but also raises new hopes for possible treatments in the future.
"Age-related macular degeneration is a major cause of vision impairment and blindness among older Australians and with our ageing population, this problem will get worse unless we can better understand the disease process and develop ways to prevent or treat it."