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London, UK - Abnormalities in the retinal microvasculature identify patients at increased risk of stroke, a new study shows, suggesting retinal photography may be a useful screening tool for populations at risk. The new report appears in the October 6, 2001 issue of the Lancet.1
Abnormalities in the retinal microvasculature are thought to stem from arteriolar damage subsequent to hypertension and other vascular problems. Although retinal examination is already recommended for people with hypertension, the researchers write, its value has been challenged. This is partly because clinical ophthalmoscopy is "highly unreliable" in detecting these lesions, and partly because there has been no evidence that detection of these abnormalities would give any prognostic information beyond that gleaned from traditional risk-factor profiles.
The data reported here "suggest that retinal microvascular abnormalities can be reliably detected with retinal photographs, and are predictive of stroke, beyond that attributable to stroke risk factors," the researchers, led by Dr Tien Yin Wong (Department of Ophthalmology, University of Wisconsin, Madison, WI) conclude.
ARIC study
The study used data on 10358 men and women from the Atherosclerosis Risk in Communities (ARIC) study, a large population-based study of middle-aged subjects living in four US communities. Participants had undergone retinal photography as part of their study examinations. The caliber of retinal arterioles and venules was measured after digital conversion of the photographs, and a summary arteriole-to-venule ratio (AVR) was calculated as an index of arteriolar narrowing.
Over 3.5 years of follow-up, 110 subjects had incident strokes. After adjustment for age, sex, race, 6-year mean arterial blood pressure (BP), diabetes, and other stroke risk factors, most retinal microvascular characteristics were predictive of stroke - in most cases, more than doubling the risk.
Relative risk of stroke associated with retinal microvascular characteristics|
Microvascular characteristic |
Relative risk |
95% CI |
|
Any retinopathy | 2.58 | 1.59-4.20 |
|
Microaneurysms | 3.11 | 1.71-5.65 |
|
Soft exudates | 3.08 | 1.42-6.68 |
|
Blot hemorrhages | 2.55 | 1.27-5.14 |
|
Flame-shaped hemorrhages | 2.26 | 1.00-5.12 |
|
Arteriovenous nicking | 1.60 | 1.03-2.47 |
The relative risk of stroke increased with a decreasing AVR (p=0.03). The associations were similar for ischemic strokes, and for strokes in subjects with hypertension, with or without diabetes.
In this study, retinal abnormalities were strongly related to current and past BP, as well as to markers of inflammation and endothelial dysfunction, Wong et al note. "Thus, in ARIC, retinal abnormalities allow us to investigate, noninvasively, the association of microvascular pathology, due to hypertension, inflammation, endothelial dysfunction, and other unmeasured factors, with cerebrovascular disease," they write.
