Calcium deposits in the eye linked to age-related blindness

Age-related macular degeneration is one of the most common forms of blindness, affecting 1 in every 5 UK citizens over the age of 75.

Age-related macular degeneration is one of the most common forms of blindness, affecting 1 in every 5 UK citizens over the age of 75. There are currently over 500,000 cases, and this number is set to rise to 700,000 by 2020, according to National Health Services.

 

What is AMD?

AMD causes vision to slowly deteriorate and is most common in older adults. There's currently no way to detect the onset of the disease early, as researchers don't have the proper knowledge of the condition.

The disease usually starts when an accumulation of deposits containing protein and fat - called drusen - build up in the retina. These deposits make it impossible for nutrients to reach the light-sensitive cells in the eye called photoreceptors, which create waste as they're recycled.

Drusen keep the waste from exiting the retina, increasing the build up. This is the first clear understanding physicians have as to how drusen grow in size as people age, but the origins have remained unknown until recently.

 

Calcium-based spheres linked to AMD

A new study performed by the University College London and published in Proceedings of the National Academy of Sciences discovered a potential explanation for the sudden existence of drusen in the eye. Small calcium-based hydroxyapatite spheres attract proteins and fats to their surfaces. The protein and fat eventually accumulate to form drusen.

Researchers performed postmortem assessments of 30 eyes from donors ranging from 43 to 96 years old. To determine where the spheres were located, they used fluorescent dyes. The results showed that some of the spheres were covered in amyloid beta - commonly associated with Alzheimer's disease. There's a chance that if scientists could find a method to detect these spheres early, they could not only prevent the onset of AMD, but Alzheimer's as well.

"The calcium-based spheres are made up of the same compound that gives teeth and bone their strength, so removal may not be an option," said Imre Lengyel, senior research fellow at the UCL Institute of Ophthalmology. "However, if we could get to the spheres before the fat and protein build up, we could prevent further growth. This can already be done in the lab, but much more work is needed before this could be translated into patients."

The findings mention that it's still unknown whether the calcium spheres are a symptom or cause of AMD. Regardless, drusen aren't only helpful diagnostic tools, but if strategies can be developed to prevent build-up of these deposits, physicians may be able to stop AMD altogether.

 

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