Enzyme Deficiency Behind Age-Related Vision Loss

Deficiency of an enzyme called DICER-1 could lead to age-related macular degeneration (AMD), a most common form of vision loss and blindness.

Deficiency of an enzyme called DICER-1 could lead to age-related macular degeneration (AMD), a most common form of vision loss and blindness. The discovery has been effected thanks to research conducted with help from Australian eye donors.

AMD affects one in every seven Australians over 70 and is a leading cause of blindness among the elderly. Patients suffering the disease experience difficulties reading or recognising faces. The research findings could lead to new treatments for this previously untreatable disease.

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Professor Jan Provis from the The Australian National University’s Vision Centre said the research found that the enzyme, DICER-1, is reduced in the eyes of those suffering the ‘dry’ form of AMD, causing changes in cells that lead to the premature death of the vision cells.

“We’ve known for some time that cell death is the cause of ‘dry’ AMD. What was not clear until now was which mechanism caused the cells to die,” said Professor Provis.

“This discovery relied on the help of Australians who donated their eyes through the Lions NSW Eye Bank.

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“Thanks to these donations, we were able to collect critical evidence to confirm that a deficit of DICER-1 was causing the cells to die,” she said.

Professor Provis said that understanding what causes the cell death takes scientists a step closer to finding a possible treatment for this form of AMD. The discovery identifies a new role for DICER-1 which is also implicated in some forms of cancer.

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“Dry macular degeneration affects very large numbers of elderly Australians, and is presently untreatable. The existing forms of AMD therapy, that involve injections into the eye, are not appropriate for this ‘dry’ form of the disease. The research not only shows that DICER-1 is reduced, but also identifies the regulator that is responsible for its reduction. That is where new therapies can be targeted,” said Professor Provis.

Jan Provis is Professor of Anatomy in the ANU Medical School, and Associate Director of the Vision Centre. The Vision Centre is funded by the Australian Research Council as the ARC Centre of Excellence in Vision Science.