New findings could aid early diagnosis of common eye disease

New findings could aid early diagnosis of common eye disease in elderly

Researchers at the University of Auckland have discovered that age-related macular degeneration – the most common form of vision loss in the elderly – extends to areas outside the macula, a discovery which could prove critical in helping prevent the onset of the disease.

Molecular cell biologist Dr Monica Acosta led the Health Research Council of New Zealand-funded study, which used both human donor tissues from the New Zealand Eye Bank and animal models to investigate the early stages of age-related macular degeneration (AMD).

Clinically, AMD is diagnosed when yellow protein deposits called drusen are seen in the macula – a small part in the centre of the eye’s retina, about the size of a pinhead, which is responsible for clear and detailed central vision. However, Dr Acosta and her team have found that molecular changes associated with AMD, including the presence of drusen and changes in cell communication, occur outside the macula. Inflammation also occurs in an area just above the retina called the choroid.

“Until now, people have focused on developing interventions to prevent the death of photosensitive cells in the macula. Our findings suggest that the changes in the macula that result in vision loss may actually be due to changes in the choroid, and that visual function should be monitored across the retina,” says Dr Acosta.

To further investigate this finding, Dr Acosta’s group used an animal model of AMD to test alternative treatment options. They found that administering a peptide called connexin 43, which acts on the channels (gap junctions) between cells, significantly reduced inflammation in the choroid and retina. Co-researchers Professors Colin Green and Helen Danesh-Meyer from the university’s Ophthalmology Department have been researching different aspects of this molecule for many years.

“We don’t know if this molecule is interacting with the outer part of the channels or the inner part, or what the mechanism of action is. However, it’s intervening at a critical step of the damaging process to restore retinal function and stop the spread of the disease.”
Dr Acosta says looking at the ways cells communicate with each other could be one of the keys to developing alternative therapies for AMD.

“The disease affects people over 60 for whom genetic and environmental factors, principally as a consequence of light damage, may cause changes to the macular area. We need to find the reasons for this and a cure as it’s devastating for the elderly and their families.”

For this study, the team used human donor tissue from three patients who had advanced AMD. Dr Acosta hopes that by using more human donor tissue, and improving the animal model, they will be able to look for inflammation in other areas not normally targeted, with the aim of stopping the progress of the disease.

“Now that we have identified a molecule with the ability to combat the spread of inflammation, oxidative stress, and cell death, as well as trigger repair mechanisms, we have good prospects for advancing that line of research.”

Dr Acosta says that while their research is in the early stages, it offers exciting possibilities for the treatment of retinal diseases.

“I’m convinced that we have the clues for finding the right therapies and interventions at the protein and cellular level. With the support of my colleagues in optometry and ophthalmology, it’s possible to apply or translate our findings to a clinical environment, and this is something we will look at pursuing in the near future.”

Information: Dr Monica Acosta
Department of Optometry and Vision Science
The University of Auckland
Phone: +64 9 923 6069
Email: m.acosta@auckland.ac.nz

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