Calcium in the back of the eye may be a trigger for AMD

21 January 15

written by:

Ade Deane-Pratt

(more articles)

A mineral found in teeth and bones is identified in the macula for the first time.

An international team of researchers has found that tiny lumps of calcium phosphate may be an important trigger for age-related macular degeneration (AMD). Calcium phosphate is a group of minerals that’s found in cow’s milk and blood. This is the first time that these mineral deposits have been linked to AMD.

AMD gets its name because it affects the macula, the central area of the retina at the back of the eye that’s responsible for the sharp, direct vision required for reading and driving. It develops slowly over decades, with the build-up of fatty protein deposits in the retina, which cause damage by blocking the flow of nutrients into the light-sensitive portion of the eye, and of waste products out. Scientists have known about these deposits for over a century, but their origins remained a mystery.

In the current study, Professor Richard Thompson at the University of Maryland School of Medicine and colleague Dr Imre Lengyel of University College London led a team who studied retinal samples from a group of elderly patients, some of whom had AMD.

Calcium phosphate is common in the body

Results showed that the AMD samples contained tiny balls of a type of calcium phosphate known as hydroxyapatite, or HAP. We already know that HAP is common in the body – it makes up the hard part of teeth and bones – but it had never been identified in this part of the eye before.

Thompson and Lengyel discovered that the fatty protein deposits seem to form around the tiny bits of HAP. Over years, the clumps build up.

A biomarker for early detection?

“This is a very important discovery because HAP found in this part of the eye could be an important biological marker, or ‘biomarker’ that would help us to detect AMD early on, before significant sight loss has occurred,” said Dr Dolores M Conroy, Director of Research at Fight for Sight.

“It also gives us a new target for treatment that could potentially slow or stop AMD from progressing. This was the number one research priority identified in our Sight Loss and Vision Priority Setting Partnership by people affected by AMD.”

The results were published in the Proceedings of the National Academy of Sciences.

Read more about the research project:

How do calcium and protein build up in the eye and what’s the link to AMD?

1 July 15 - 1 June 17

A surprise link to the mineral found in teeth and bones.

Find out more