HYPERTENSIVE RETINOPATHY

Arterial hypertension is a major risk factor for cardiovascular disease, which is a leading cause of morbidity and mortality. The effects of arterial hypertension can be directly visualized in the fundus. These changes may involve the retinal arterioles, the choroid, and the optic nerve. Observation of these fundus changes may lead

to a diagnosis of hypertension in a previously undiagnosed patient.

Symptoms

Mild to moderate degrees of hypertension often result in asymptomatic fundus changes. Severe or malignant hypertension may produce fundus changes resulting in blurred or distorted vision. These fundus changes include central macular thickening or lipid deposition from retinal vascular or optic disc leakage. Serous macular detachment secondary to choroidal ischemia may occur also. In addition, transient obscurations of vision may result from hypertension-induced optic disc edema.

Clinical Features

The clinical features of hypertensive retinopathy are categorized as retinal vascular changes, choroidopathy, and optic neuropathy. The large retinal arterioles may be focally or difusely narrowed. The arterial walls become thickened due to leakage of blood elements into the wall, which may lead to focal ischemic whitening of the retina, producing the classic cotton wool spot. The focal ischemia may also lead to surrounding microvascular abnormalities in addition to retinal hemorrhages and intraretinal serous exudation and lipid deposition. Hypertensive choroidopathy results from choroidal ischemia, leading to necrosis of the overlying retinal pigment epithelium (RPE) and often resulting in serous retinal detachments. Changes in the pigment epithelium (Elschnig spots) and larger choroidal vessels (Segrist streaks) remain after resolution of the serous detachment. Severe or malignant hypertension often leads

to bilateral optic disc edema presumed to be due to ischemia. Lipid deposition may result in formation of a macular star.

Pathology/Pathogenesis

Pathogenesis of hypertensive retinopathy probably begins with failure of retinal vascular autoregulation, leading to endothelial cell alterations and breakdown of the blood-retinal barrier, resulting in leakage of fluid, blood, and macromolecules into the retina. Also, occlusion of terminal retinal arterioles can lead to nerve fiber layer infarction. The choroidopathy results from acute multifocal areas of fibrin-platelet occlusion and necrosis of choroidal arteries and choriocapillaris which leads to necrosis of overlying RPE.

Treatment/Prognosis

The primary treatment for hypertensive retinopathy is systemic arterial blood pressure control. The visual prognosis is excellent in mild to moderate cases of hypertensive retinopathy. When there is foveal edema and/or lipid deposition, a variable degree of permanent visual loss may occur due to structural changes in the retina and RPE. The presence of associated retinal vascular conditions, including arterial macroaneurysms and branch retinal vein obstruction (BRVO) also may affect

the prognosis.

Systemic Evaluation

The systemic evaluation should focus on the etiology of the hypertension. As many as 85% to 90% of cases are classified as essential hypertension. Secondary causes should be ruled out in selected patients.

Fundus photograph of a 48-year-old man with a recent diagnosis of hypertension. He had diffuse and focal arterial narrowing, arterial-venous crossing changes, and cotton wool spots.

A 22-year-old woman was admitted to the hospital with severe headaches. Her blood pressure was 240/150 mm Hg. She had bilateral optic disc edema, macular stars, cotton wool spots, and intraretinal hemorrhages.

Fluorescein angiogram of a 60-year-old woman with newly onset hypertension reveals areas of focal attenuation of the proximal arterioles.

This fundus photograph demonstrates the late sequelae of hypertensive choroidopathy: Elschnig spots (areas of focal hyperpigmentation) and Segrist streaks (areas of choroidal sclerosis).

A 32-year-old woman with severe hypertension and seizures complained of visual loss during her third trimester of pregnancy. She had serous detachment of the macula, with patchy white areas, indicating infarction of the retinal pigment epithelium.

The fluorescein angiogram of the same patient revealed multiple areas of leakage at the level of the retinal pigment epithelium resulting from choroidal ischemia.

Idiopathic juxtafoveolar retinal telangiectasis (the terms parafoveal telangiectasis and juxtafoveal telangiectasis are also used) refers to a group of retinal vascular disorders in which a portion of the parafoveal capillary network develops dilated and tortuous blood vessels. Patients with idiopathic juxtafoveolar retinal telangiectasis (IJRT) may be categorized into three subgroups that have distinct retinal findings, but all are located in the parafoveal retina. In all groups, the telangiectasis is a primary condition rather than a finding secondary to a retinal disorder such as diabetic retinopathy or venous occlusion.

Symptoms

The primary visual symptom of IJRT is blurred central vision in one or both eyes. Patients with group 1 IJRT have blurred vision in one eye only. Group 2 patients, which includes both women and men, have bilateral, mild to moderate central visual loss that typically begins in the fifth or sixth decade of life. In group 3 IJRT, a rare condition, patients have bilateral visual loss that is associated with central nervous system symptoms.

Clinical Findings

Group 1 patients have unilateral retinal telangiectasis in the parafoveal region that may consist of a single aneurysm or a large cluster of aneurysms. The telangiectatic vessels and aneurysms are easily visible and are accompanied by retinal edema. Cystoid macular edema and lipid exudate also may be present. These patients, who are predominantly male, tend to have mild-to- moderate visual loss beginning in their 30s and 40s.

In group 2 IJRT, the retina has a subtle gray appearance, with loss of the normal retinal transparency, and bilateral thickening of the parafoveal retina. Superficial retinal crystals may form in the early or late stage of the disease. Telangiectatic vessels, foveal cysts, and lipid exudate are clinically absent. Early in the disease, group 2 patients may develop “right angle venules,” which are dilated and blunted in appearance. With time, pigmentary plaques may form in the neurosensory retina. Group 2 patients may have visual loss due to retinal pigment epithelial atrophy or subretinal new vessels.

Group 3 patients demonstrate progressive central macular capillary nonperfusion in addition to aneurysmal dilation of the parafoveal capillary bed.

Ancillary Testing

Fluorescein angiography is the most useful test in demonstrating juxtafoveolar telangiectasia. In group 1 IJRT, filling of the telangiectatic vessels is prompt, with late leakage in only one eye. Group 2 IJRT is characterized by bilateral telangiectasis involving the temporal portion of the juxtafoveolar retina (usually confined to 1 disc diameter of the center of the fovea). Subretinal neovascularization may be detected. Patients in group 3 have occlusion of the juxtafoveolar capillary network in both eyes.

Pathology/Pathogenesis

The underlying cause of IJRT is not known. Group 1 IJRT is most likely a congenital retinal telangiectasis. Group 2 IJRT may be the result of a low-grade, chronic venous stasis in the macula. Electron microscopic findings reveal changes in the retinal capillaries similar to those found in diabetic retinopathy.

Treatment/Prognosis

Photocoagulation to leaking microaneurysms is the treatment of choice in group 1 IJRT. In group 2 IJRT, subretinal neovascularization may be treated with confluent photocoagulation. Although grid photocoagulation has been advocated by some retinal experts to treat intraretinal edema in group 2 patients, laser treatment does not appear to reverse the retinal pigment epithelial alterations that are the ultimate cause of visual loss. Laser therapy may be effective in rare cases of extrafoveal subretinal neovascularization. The role of photodynamic therapy is unclear.

Systemic Evaluation

No definitive systemic associations occur with group 1 or group 2 IJRT. Controversy exists as to whether there is a link between group 2 IJRT and diabetes mellitus.

Group 3 IJRT has been associated with central nervous system disease.

Group 2 idiopathic juxtafoveolar retinal telangiectasis is the most common type of parafoveal retinal telangiectasis. It is characterized by subtle abnormalities of the parafoveal capillary system.

Other findings in patients with group 2 idiopathic juxtafoveolar retinal telangiectasis include “right angle venules” and intraretinal pigment accumulation.

Early findings include loss of the normal retinal transparency in the temporal parafoveal region with irregular, telangiectatic vessels. Group 2 IJRT is bilateral but may be asymmetric.

Superficial retinal crystals may be seen in addition to the retinal vascular and pigmentary alterations.

Fluorescein angiography reveals irregularities of the parafoveal capillary network. Telangiectatic vessels are more commonly observed temporal to the fovea.

Some patients with group 2 idiopathic juxtafoveolar retinal telangiectasis develop subretinal neovascularization. It has been proposed that the subretinal new vessels originate from the retinal circulation rather than the choroid. Fluorescein angiography reveals a lacy vascular network that leaks throughout the fluorescein study.