Patients with a specific form of age-related macular degeneration (AMD), which is a leading cause of blindness in the United States, have been identified as being at significant risk for cardiovascular disease and stroke.
This is according to new research from New York Eye and Ear Infirmary of Mount Sinai, this study is the fist to demonstrate a link between the disorders.
Lead author of the study R.Theodore Smith, MD, PhD, professor of ophthalmology at the Icahn School of Medicine at Mount Sinai, said:
“For the last three decades researchers have suggested an association between AMD and cardiovascular disease, but there has been no conclusive data on this until now. Our retinal team answered this important question by focusing on two different varieties of AMD that can be seen with advanced retinal imaging. We discovered that only one form of AMD, that with subretinal drusenoid deposits, is tightly connected to high-risk vascular diseases, and the other form, known as drusen, is not,
if ophthalmologists diagnose or treat someone with the specific subretinal drusenoid deposits form of AMD, but who otherwise seems well, that patient may have significant undetected heart disease, or possibly carotid artery stenosis that could result in a stroke. We foresee that in the future, as an improved standard of care, such patients will be considered for early referral to a cardiologist for evaluation and possibly treatment.”
AMD is the leading cause of blindness and visual impairment in those over 65 years old.
It is caused by damage to the central area of the retina called the macula, which is responsible for reading and driving vision.
One major form of early AMD is known as druse, which is where small yellow cholesterol deposits form in a layer under the retina.
Another form is subretinal drusenoid deposits (SDD) which requires high-tech retinal imaging to detect. These deposits are made up of fatty lipids and other materials, however, they form in a different layer beneath the light sensitive retina cells.
Researchers at Mount Sinai analysed 126 patients with AMD by using optical coherence tomography, which is an advanced imaging system that provides high-resolution cross-sectional scans of the retina.
The patients part of the study also had to answer questionnaires about their health history including heart disease and stroke.
Of the 126 patients, 64 had drusen and 62 had SDD. 51 patients (40%) reported that they a cardiovascular disease or had suffered from a stroke, 66% of these patients had SDD.
In contrast, of the 75 patients who did not have any known heart disease or past stroke, only 19% had SDD.
Thus meaning, patients with cardiovascular disease or past stroke were three times more likely to have SDD than patients without.
From these results, the researchers have suggested that the underlying heart and vascular disease likely compromises blood circulation in the eye, which is leading to the SDDs beneath the retina and ultimately causing vision loss and blindness.
Study author Jagat Narula, MD, PhD Associate Dean of Global Affairs and Professor of Medicine (Cardiology), and Radiology, at the Icahn School of Medicine at Mount Sinai, said:
“We believe poor ocular circulation that causes SDDs is a manifestation of underlying vascular disease. This has important public health implications and can facilitate population screening and disease detection with major impact,
Seen in an eye clinic, such patients should be prompted to see a cardiologist. On the other hand, if clinically substantiated in prospective studies, SDDs could emerge as a risk marker for underlying vascular disease in asymptomatic patients in primary care or a cardiology clinic. The temporal relationship between SDDs and macrovascular disease will also need to be established in prospective studies which are currently in progress.”
The researchers also collected blood samples from the patients, and results demonstrate genetic risk factors may also play a role in SDD cases in addition to vascular cases.
More specifically, they discovered that the ARMS2 gene acted independently of vascular disease to cause SDD in some patients.
The Chief of the Retina Service for the Mount Sinai Health System, Richard B. Rosen, MD said: “This study further demonstrates that AMD is not a single condition or an isolated disease, but is often a signal of systemic malfunction which could benefit from targeted medical evaluation in addition to localised eye care,
It helps bring us one step closer to unraveling the mystery of this horrible condition which robs so many patients of the pleasure of good vision during their later years. “
