Retinal Artery and Vein Occlusions

Retinal Artery Occlusion

A retinal artery occlusion (RAO) is the result of blockage of arterial blood flow into the retina, usually as a result of an embolus. Interruption of blood flow to the retina reduces oxygen flow to the cells in the retina, resulting in dysfunction of these cells; this translates into vision loss which in most cases can be permanent. A retinal artery occlusion can affect the entire retinal circulation, a central retinal artery occlusion (CRAO), or may impact a portion of the retinal circulation in a branch retinal artery occlusion (BRAO).  Symptoms of RAO may include sudden, dramatic vision loss in a CRAO or a horizontal shadow coming over the vision in a BRAO.

Cause

Blockage of retinal arteries typically occurs as a result of emboli, which may originate in the heart and/or neck. Risk factors for RAO include high blood pressure, high cholesterol, valvular heart disease, carotid artery disease, and clotting disorders.

Diagnosis

Diagnosis of RAO is made with dilated examination, though ancillary tests such as ocular coherence tomography (OCT) and fluorescein angiography are very useful in solidifying the diagnosis. A fluorescein angiogram enables visualization of retinal blood flow and may assist in understanding the extent of retinal damage as a result of impaired blood flow to the retina.

RAO Treatment

Unfortunately, treatment options are of limited utility in rehabilitating vision loss. Management often centers on evaluation of systemic health and assessment of stroke risk factors. Additional testing is commonly recommended and may need to be performed at an emergency department.

Retinal Vein Occlusion

A retinal vein occlusion (RVO) is the result of blockage of the blood vessels that take blood out of the retina. A venous occlusion can occur to the central retinal vein which drains blood from the entirety of the retina, a central retinal vein occlusion (CRVO); it may also occur in only a section of the retinal veins, impacting a smaller area, in a branch retinal vein occlusion (BRVO). Symptoms of a RVO may range from nothing to a sudden, significant decrease in vision.

Cause

Risk factors for retinal vein occlusion include high blood pressure, heart disease, glaucoma, clotting disorders, and age (greater than 50).

Diagnosis

Diagnosis of RVO is made with dilated fundus examination, though ancillary tests such as ocular coherence tomography (OCT) and fluorescein angiography contribute to an enhanced understanding of the extent of the circulatory disturbance.

RVO Treatment

Management of RVO varies depending on the severity of the vascular event. Many cases can be managed with close observation. If there is swelling in the macula due to RVO, treatment is typically recommended in order to reduce swelling. If there is extensive bleeding in the retina and/or the vitreous, treatment is usually implemented. Treatment of retinal vein occlusions centers on the administration of potent medications via intravitreal injections. Laser treatment may also be recommended as an adjuvant therapy in certain cases.