Ocular effects of hypertension

INTRODUCTION — A number of ocular abnormalities are directly or indirectly associated with hypertension [1,2]. These include some that are a direct consequence of elevated blood pressure, including hypertensive retinopathy, choroidopathy, and optic neuropathy. With other abnormalities, hypertension is a significant risk factor, including retinal vein and artery occlusion, retinal artery emboli, and diabetic retinopathy. In addition, hypertension may accelerate nonvascular eye disease, including age-related macular degeneration and glaucoma.

OCULAR DISEASES DIRECTLY RELATED TO HYPERTENSION — Fundoscopy should be part of the physical examination on every patient with newly diagnosed hypertension since the retina is the only part of the vasculature that can be visualized noninvasively. Pupillary dilatation with a short-acting mydriatic (eg, tropicamide 1%) is almost always useful since the mild changes are hard to quantify, even with retinal photography [3]. Newer approaches to retinal imaging, such as optical coherence tomography angiography (OCTA), may also be useful in evaluating hypertensive retinopathies [4]. (See "Initial evaluation of adults with hypertension", section on 'Physical examination'.)

The most common ocular diseases directly related to hypertension are progressively increasing retinal microvascular changes, which are subsumed under the name "hypertensive retinopathy." Classically, the features are divided into four degrees, and their morphological classification has been widely used [5]. However, a more pathophysiological division has been proposed and seems more logical [3,6]. This three-degree classification includes mild, moderate, and severe (image 1):

●Mild – Retinal arteriolar narrowing related to vasospasm, arteriolar wall thickening or opacification, and arteriovenous nicking, referred to as "nipping" (image 1) [3].

●Moderate – Hemorrhages, either flame or dot-shaped, cotton-wool spots, hard exudates, and microaneurysms (image 1).

●Severe – Some or all of the above, plus optic disc edema (image 1). The presence of papilledema mandates rapid lowering of the blood pressure. Symptoms of papilledema are discussed elsewhere. (See "Overview and differential diagnosis of papilledema".)

Generalized narrowing and nicking are related to current and previous blood pressure levels; by comparison, focal narrowing, hemorrhages, and exudates are related only to current blood pressure levels [7].

Retinal arterial narrowing, a predictor of the future development of hypertension, is linked to nonocular systemic vascular diseases, particularly stroke [8,9]. In a study of 2907 hypertensives who had gradable retinal photographs and were followed for an average of 13 years, hypertensive retinopathy predicted the long-term risk of stroke, independent of the level of blood pressure [10]. Substantial evidence also exists for the association with coronary heart disease, left ventricular remodeling, and kidney damage [11-14].

The presence of hypertensive retinopathy should serve as an additional stimulus to ensure adequate control of hypertension. With good control, retinopathy may regress, providing an easily obtained indicator of success [15].

HYPERTENSION AS A RISK FACTOR FOR OCULAR DISEASE — Hypertension increases the risk of a number of ocular diseases. The most common is diabetic retinopathy, which is also the most common cause of blindness in developed societies. In a multiethnic cohort in the United States, retinopathy was found in 33 percent of diabetics over age 40 years, 8 percent of whom had vision-threatening retinopathy [16]. Multiple factors may be involved in the added risk of hypertension to the development and progression of diabetic retinopathy, including increased endothelial damage [17].

Fortunately, good control of hypertension can reduce the threat of diabetic retinopathy, independent of control of hyperglycemia [18]. In the United Kingdom Prospective Diabetes Study, the risk of retinopathy was reduced 10 percent for each 10 mmHg lower systolic blood pressure [18]. Goal blood pressure and choice of antihypertensive therapy in patients with diabetes and diabetic retinopathy are discussed elsewhere in detail. (See "Diabetic retinopathy: Prevention and treatment", section on 'Good blood pressure control' and "Treatment of hypertension in patients with diabetes mellitus".)

Other ocular diseases wherein hypertension serves as a risk factor include retinal venous and arterial occlusion, retinal emboli, retinal macroaneurysm, and anterior ischemic optic neuropathy [1]. (See "Retinal vein occlusion: Epidemiology, clinical manifestations, and diagnosis" and "Central and branch retinal artery occlusion" and "Nonarteritic anterior ischemic optic neuropathy: Epidemiology, pathogenesis, and etiologies".)

OCULAR DISEASES WHEREIN HYPERTENSION MAY BE A RISK FACTOR — The risk for two of the more common causes of vision loss, age-related macular degeneration and glaucoma, may be increased by the presence of systemic hypertension. Although cross-sectional data support an association [19,20], the evidence is not conclusive. It should be noted that systemic hypotension, especially at night from excessive antihypertensive therapy, has been shown to further reduce blood flow to the optic nerve, accentuating the damage of high intraocular pressure from glaucoma [21]. (See "Open-angle glaucoma: Epidemiology, clinical presentation, and diagnosis".)

SUMMARY

●The most common ocular diseases directly related to hypertension are progressively increasing retinal microvascular changes, which are subsumed under the name "hypertensive retinopathy." The three-degree classification includes mild, moderate, and severe disease. The presence of papilledema mandates rapid lowering of the blood pressure. (See 'Ocular diseases directly related to hypertension' above.)

●Hypertension increases the risk of a number of ocular diseases, with the most common being diabetic retinopathy. Other ocular diseases wherein hypertension serves as a risk factor include retinal venous and arterial occlusion, retinal emboli, retinal macroaneurysm, and anterior ischemic optic neuropathy. (See 'Hypertension as a risk factor for ocular disease' above.)

●The risk for two of the more common causes of vision loss, age-related macular degeneration and glaucoma, may be increased by the presence of systemic hypertension. (See 'Ocular diseases wherein hypertension may be a risk factor' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Norman M Kaplan, MD, who contributed to an earlier version of this topic review.