Findings suggest potential screening and disease detection opportunities.
Patients with a specific form of age-related macular degeneration (AMD) characterized by subretinal drusenoid deposits (SDD) are at a significant risk for cardiovascular disease and stroke, according to research published in the July issue of Retina.
The study, conducted by researchers from New York Eye and Ear Infirmary of Mount Sinai, is the first to demonstrate an association between the disorders.
“For the last 3 decades, researchers have suggested an association between AMD and cardiovascular disease, but there has been no conclusive data on this until now.” lead author R. Theodore Smith, MD, PhD, Professor of Ophthalmology at the Icahn School of Medicine at Mount Sinai, said in a press release. “Our retinal team answered this important question by focusing on 2 different varieties of AMD that can be seen with advanced retinal imaging. We discovered that only 1 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,”
AMD is known to be the leading cause of visual impairment and blindness among individuals over 65 years of age in the United States. AMD is the result of damage to the central area of the retina, the macula, which is responsible for reading and vision.
Drusen is a major form of early AMD, characterized by small yellow cholesterol deposits forming in a layer under the retina. These deposits can deprive the retina of blood and oxygen, leading to vision loss.
The other major form of early AMD involves the presence of SDD and is lesser known. High-tech retinal imaging is required to detect SDD. Similar to the deposits found in patients with drusen, SDD are made of fatty lipids and other materials. However, they form in a different layer beneath the light sensitive retina cells, also causing vision loss. Currently, there is no known treatment available for SDD.
Researchers at Mount Sinai examined patients using optical coherence tomography (OCT), an advanced imaging system that provides high-resolution cross-sectional scans of the retina. Patients were also asked to answer questionnaires about their health history, including heart disease and stroke.
There were 126 patients participating in the study, including 64 patients with drusen and 62 patients with SDD. Of the 51 patients who reported having cardiovascular disease or a past stroke, 66% had SDD. Only 19% of the 75 patients who did not have known heart disease or stroke had SDD.
Researchers found that patients with cardiovascular disease or stroke were 3 times more likely to have SDD than participants without.
"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,” Smith said in the press release. “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.”
The researchers suggest that the underlying heart and vascular disease likely compromises blood circulation in the eye, which may lead to the SDDs beneath the retina.
“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,” 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, explained in the press release. “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 had also collected patient blood samples as part of the study. Results showed that genetic risk factors may also play a role in SDD cases in addition to vascular causes. The ARMS2 gene was found to act independently of vascular disease to cause SDD in some patients.
“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 localized eye care,” Richard B. Rosen, MD, Chief of the Retina Service for the Mount Sinai Health System, said in the press release. “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.”