III The above and retinal hemorrhages, exudates, and cotton-wool spots

IV Severe grade III and papilloedema Scheie grade features:

0 No changes

1 Barely detectable arterial narrowing

2 Obvious arterial narrowing with focal irregularities plus light reflex changes

3 Grade 2 plus retinal hemorrhages and exudates

4 Grade 3 plus silver wiring and papilledema Signs of hypertensive retinopathy are com-

mon and are correlated with elevated blood pressure. Recent studies show that some of these signs (e.g., retinal hemorrhages, microaneurysms, and cotton-wool spots) predict stroke and death from stroke independently of elevated blood pressure and other risk factors. Patients with these signs of retinopathy may benefit from close monitoring of cerebrovascular risk and intensive measures to reduce that risk.

19.5.2 Pathophysiology

The retinal circulation undergoes a series of pathophysiological changes in response to elevated blood pressure. In the initial vasoconstrictive stage, there is vasospasm and an increase in retinal arteriolar tone owing to local autoregulatory mechanisms. This stage is seen clinically as a generalized narrowing of the retinal arterioles. Persistently elevated blood pressure leads to intimal thickening, hyperplasia of the media wall, and hyaline degeneration in the subsequent sclerotic stage. This stage corresponds to more severe generalized and focal areas of arteriolar narrowing, changes in the arteriolar and venular junctions (i.e., arteriovenous nicking or nipping), and alterations in the arteriolar light reflex (i.e., widening and accentuation of the central light reflex, or “copper wiring”).

This is followed by an exudative stage in which there is disruption of the blood–retina barrier, necrosis of the smooth muscles and endothelial cells, exudation of blood and lipids, and retinal ischemia. These changes are manifested in the retina as microaneurysms, hemorrhages, hard exudates, and cotton-wool spots. Swelling of the

optic disk may occur at this time and usually indicates severely elevated blood pressure (i.e., malignant hypertension).

Because better methods for the control of blood pressure are now available in the general population, malignant hypertension is rarely seen. In contrast, other retinal vascular complications of hypertension, such as macroaneurysms and branch-vein occlusions, are not uncommon in patients with chronically elevated blood pressure.

19.5.3 Blood Pressure

Numerous studies have confirmed the strong association between the presence of signs of hypertensive retinopathy and elevated blood pressure. Two studies have further evaluated the effect of a history of elevated blood pressure on the occurrence of specific retinal signs. In both studies, generalized retinal arteriolar narrowing and arteriovenous nicking were associated with an elevation in blood pressure that had been documented 6–8 years before the retinal assessment; the studies were controlled for concurrent blood pressure levels. This association suggests that generalized narrowing and arteriovenous nicking are markers of vascular damage from chronic hypertension. In contrast, other signs (focal arteriolar narrowing, retinal hemorrhages, microaneurysms, and cotton-wool spots) were related to current but not previous blood pressure levels and may therefore be more indicative of the severity of recent hypertension.

Furthermore, the observation of signs of retinopathy in people without a known history of hypertension suggests that these signs may be markers of a prehypertensive state. For example, generalized and focal narrowing of the retinal arterioles has been shown to predict the risk of hypertension in normotensive persons. Other factors unrelated to hypertension (e.g., hyperglycemia, inflammation, and endothelial dysfunction) may also be involved in the pathogenesis of retinopathy.

19.5.3.1 The Risk of Stroke

The strongest evidence of the usefulness of an evaluation of hypertensive retinopathy for risk