Patients with a specific form of age-related macular degeneration (AMD) are also highly likely to have either underlying heart disease, according to a new study.
This research from New York Eye and Ear Infirmary of Mount Sinai, published November 17 in BMJ Open Ophthalmology, is the first to identify which types of high-risk cardiovascular and carotid artery disease, associated with certain types of strokes, are linked to AMD, a leading cause of blindness.
Lead author Dr R. Theodore Smith, Professor of Ophthalmology at the Icahn School of Medicine at Mount Sinai, explained how the findings could prompt increased screening to save vision, diagnose undetected heart disease, and prevent adverse cardiovascular events.
“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),” Smith said.
“This study is the first strong link between the leading cause of blindness, AMD, and heart disease, the leading cause of death worldwide. Furthermore, we also have strong evidence for what actually happens: the blood supply to the eye is directly diminished by these diseases, 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.”
Smith continued: “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. Retinal damage means vision loss and can lead to blindness.”
In the image (top), the abnormal subretinal drusenoid deposits (SDDs) are the multiple, gray, conical lesions (yellow arrows) sitting on top of the bright white band known as the retinal pigment epithelium (RPE). They are pushing and penetrating the thin white retinal layer above them. All the other retinal layers further above are normal. The eye’s blood supply, seen below the RPE and known as the choroid, is abnormally thin because the weakened heart is not pumping enough blood to the eye.
Subretinal drusenoid deposits (SDDs), a less well-known yet major form of early AMD, require high-tech retinal imaging to detect. According to the researchers, SDD deposits contain a different form of cholesterol, and form above the retinal pigment epithelium (RPE), and just beneath the light-sensitive retina cells, where the damage occurs and vision is lost. There is no known treatment for SDDs.
Smith and a team of Mount Sinai researchers initially found that patients with cardiovascular disease or stroke were more likely to have SDDs. That first-of-its-kind research was published in the July issue of Retina. This new study expands on that previous work, looking at a larger patient population, and identifies the specific severe forms of heart disease and carotid artery disease that caused the SDDs of AMD.
Researchers analysed the eyes of 200 AMD patients with retinal imaging to determine which patients had SDDs. Patients answered a questionnaire about their history of cardiovascular disease. Of the 200 patients, 97 had SDDs and 103 had drusen only. Forty-seven of the 200 had severe heart disease (19 had heart damage from heart failure or heart attack, 17 serious valve disease, and 11 stroke stemming from the carotid artery). Forty of the 47 (86%) had SDDs.
By contrast, of the 153 AMD patients who did not have these severe diseases, 57 had SDDs (43%). The researchers concluded that AMD patients with these severe cardiovascular diseases and stroke were nine times more likely to have SDDs than those without them.
Co-investigator Dr Richard B. Rosen, Chief of the Retina Service for the Mount Sinai Health System, said the study demonstrates the fact that ophthalmologists may be the first physicians to detect systemic disease, especially in asymptomatic patients.
“Detecting SDDs in the retina should trigger a referral to the individual’s primary care provider, especially if no previous cardiologist has been involved. It could prevent a life-threatening cardiac event,” he said.
Dr Jagat Narula, Director of the Cardiovascular Imaging Program at the Icahn School of Medicine at Mount Sinai, said the study has opened the door to further productive multidisciplinary collaboration between the ophthalmology, cardiology and neurology services.
“We should also focus on defining the disease severity by vascular imaging in cardiology and neurology clinics, and assess their impact on AMD and SDDs with retinal imaging. In this way we can learn which vascular patients should be referred for detection and prevention of blinding disease,” Narula said.
The study was funded by a Regeneron Pharmaceuticals Investigator-Initiated Study, Research to Prevent Blindness Challenge Grant, the Macula Foundation, a Bayer-Global Ophthalmology Award, and the International Council of Ophthalmology-Alcon Fellowship.
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