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When blindness is a clue to bigger problems

A particular type of macular degeneration is a sign of underlying heart damage.

A particular type of macular degeneration is a sign of underlying heart damage. Photo: Getty

People with a specific form of age-related macular degeneration are also highly likely to have underlying heart damage.

The damage comes from “heart failure and heart attacks, or advanced heart valve disease, or carotid artery disease associated with certain types of strokes”, according to a new study from the New York Eye and Ear Infirmary of Mount Sinai.

This research is apparently the first to identify which types of high-risk cardiovascular and carotid artery disease are linked to the eye disorder.

The upside?

Researchers suggest their findings could “prompt increased screening to save vision, diagnose undetected heart disease, and prevent adverse cardiovascular events”.

What’s the specific form of macular degeneration?

Age-related macular degeneration (AMD), a consequence of damage to the central area of the retina called the macula, is the most common macular disease in Australia. It’s responsible for half of all blindness and severe vision loss in this country.

AMD causes progressive loss of central vision. It does, however, leave the peripheral vision intact. This loss of central vision affects the ability to read, watch TV, and recognise faces.

One major form of early AMD implicates small yellow cholesterol deposits called drusen. These form under a part of the retina called the retinal pigment epithelium (RPE).

Yellow deposits under the retina are ‘drusen’, and may be a sign of macular degeneration.

Some experts suggest drusen are unlikely to cause AMD, but can increase a person’s risk of developing AMD, and they may be a sign of AMD.

The authors of the new study say that drusen deprive the retina of blood and oxygen, leading to vision loss.

They note that drusen formation can be slowed by appropriate vitamin supplementation.

The cryptic deposits

The other major form of early AMD is caused by subretinal drusenoid deposits (SDDs). The authors say these are less well-known, and require high-tech retinal imaging to detect.

Yellow arrows point to the sub-retinal drusenoid deposits. Image: Mount Sinai

These deposits “contain a different form of cholesterol, and form above the retinal pigment epithelium, and just beneath the light-sensitive retina cells, where the damage occurs and vision is lost”.

There is no known treatment for SDDs.

The researchers found that patients with cardiovascular disease or stroke were more likely to have SDDs.

Lead author Dr R. Theodore Smith, MD, professor of ophthalmology at the Icahn School, said.

“For the first time, we have been able to connect these specific high-risk cardiovascular diseases to a specific form of AMD, the one with subretinal drusenoid deposits (SDDs).”

He said the study is the first strong link “between the leading cause of blindness, AMD, and heart disease, the leading cause of death worldwide”.

How it happens

He said the researchers have “strong evidence for what actually happens”.

Professor Smith said the blood supply to the eye is directly diminished, “either by heart damage that diminishes blood supply throughout the body, or from a blocked carotid artery that directly impedes blood flow to the eye”.

He said a poor blood supply can cause damage to any part of the body, and with these specific diseases, “the destroyed retina and leftover SDDs are that damage”.

Topics: Heart health
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