The retina is the tissue layer located in the back of your eye. This layer transforms light into nerve signals that are then sent to the brain for interpretation.
When your blood pressure is too high, the retina’s blood vessel walls may thicken. This may cause your blood vessels to become narrow, which then restricts blood from reaching the retina. In some cases, the retina becomes swollen.
Over time, high blood pressure can cause damage to the retina’s blood vessels, limit the retina’s function, and put pressure on the optic nerve, causing vision problems.
Hypertensive retinopathy is retinal vascular damage caused by hypertension. Signs usually develop late in the disease. Funduscopic examination shows arteriolar constriction, arteriovenous nicking, vascular wall changes, flame-shaped hemorrhages, cotton-wool spots, yellow hard exudates, and optic disk edema. Treatment is directed at controlling blood pressure and, when vision loss occurs, treating the retina.
Systemic hypertension affects both the retinal and choroidal circulations. The clinical manifestations vary according to the degree and rapidity of rise in blood pressure and the underlying state of the ocular circulation. The most florid ocular changes occur in young patients with abrupt elevations of blood pressure, such as may occur in pheochromocytoma, malignant hypertension, or preeclampsia-eclampsia. Hypertensive retinopathy can be a surrogate marker for current and future non-ocular endorgan damage. Its detection is aided by non-mydriatic fundal photography.
Chronic hypertension accelerates the development of atherosclerosis. The retinal arterioles become more tortuous and narrower and develop abnormal light reflexes (“silver-wiring” and “copper-wiring”). There is increased venous compression at the retinal arteriovenous crossings (“arteriovenous nicking”), predisposing to branch retinal vein occlusions. Flame-shaped hemorrhages occur in the nerve fiber layer of the retina.
Acute elevations of blood pressure result in loss of autoregulation in the retinal circulation, leading to breakdown of endothelial integrity and occlusion of precapillary arterioles and capillaries that manifest as cotton-wool spots, retinal hemorrhages, retinal edema, and retinal exudates, often in a stellate appearance at the macula.
Vasoconstriction and ischemia in the choroid result in exudative retinal detachments and retinal pigment epithelial infarcts that later develop into pigmented lesions that may be focal, linear, or wedge-shaped. The abnormalities in the choroidal circulation may also affect the optic nerve head, producing ischemic optic neuropathy with optic disk swelling.
Fundal abnormalities are the hallmark of hypertensive crisis with retinopathy (previously known as malignant hypertension) that requires emergency treatment. Marked fundal abnormalities are likely to be associated with permanent retinal, choroidal, or optic nerve damage. Precipitous reduction of blood pressure may exacerbate such damage.