The retina is a delicate structure at the back of the eye responsible for converting light into neural signals for vision. For this process to work efficiently, the retina requires a steady supply of oxygen and nutrients delivered by blood vessels. When these vessels become blocked, a condition known as vascular occlusion occurs.

What Is a Retinal Vascular Occlusion?

A retinal vascular occlusion is a blockage in one of the blood vessels that supply the retina. This condition can affect either the veins (retinal vein occlusion, RVO) or the arteries (retinal artery occlusion, RAO). While both types of occlusions can lead to vision loss, their causes, symptoms, and treatment strategies differ.

Types of Retinal Vascular Occlusions

  • Retinal Vein Occlusion (RVO)
    • Central Retinal Vein Occlusion (CRVO): The blockage occurs in the main retinal vein.
    • Branch Retinal Vein Occlusion (BRVO): A smaller vein, branching off the main retinal vein, becomes blocked.
  • Retinal Artery Occlusion (RAO)
    • Central Retinal Artery Occlusion (CRAO): The central artery supplying the retina is blocked.
    • Branch Retinal Artery Occlusion (BRAO): A smaller branch of the central retinal artery is obstructed.

Causes 

Retinal Vein Occlusion: RVO is primarily caused by a blood clot or atherosclerosis (plaque buildup) in the retinal vein. Other contributing factors include:

  • High blood pressure: Can damage blood vessels, making them more susceptible to blockage.
  • Diabetes: Can cause damage to blood vessels, increasing the risk of clots.
  • High cholesterol levels: Contribute to atherosclerosis.
  • Glaucoma: Increased pressure in the eye may compress retinal veins.
  • Smoking: Promotes vascular inflammation and clot formation.

Retinal Artery Occlusion: RAO occurs when a blood clot or embolus obstructs the flow of blood to the retina. Common causes include:

  • Atherosclerosis: Narrowing of arteries due to plaque buildup.
  • Cardiovascular diseases: Conditions like atrial fibrillation or heart valve disease can lead to emboli.
  • Carotid artery disease: Plaques from the carotid artery may travel to the retina.
  • Giant cell arteritis: Inflammation of blood vessels that can reduce blood flow to the retina.
  • Rare blood disorders: Such as sickle cell anemia.

Symptoms

Retinal Vein Occlusion: Symptoms of RVO may develop suddenly or gradually and include:

  • Blurry vision: Typically affecting one eye.
  • Sudden vision loss: Partial or complete loss of vision in one eye.
  • Dark spots or floaters: Caused by bleeding in the retina.
  • Swelling in the retina (macular edema): Results in distorted or blurry central vision.

Retinal Artery Occlusion: Symptoms of RAO tend to appear suddenly and can include:

  • Sudden, painless vision loss: Often in one eye.
  • Partial vision loss: In cases of branch occlusion, affecting the part of the retina supplied by the blocked artery.
  • Blind spots: Corresponding to areas of the retina affected by the blockage.

Treatment Options

Retinal Vein Occlusion

  • Medications
    • Anti-VEGF medications injected into the eye may reduce macular edema and improve vision. Steroid injections or implants are also sometimes used to help reduce inflammation and swelling in the retina.
  • Laser therapy
    • Focal laser photocoagulation: Targets specific areas of the retina to seal leaking blood vessels.
    • Pan-retinal photocoagulation: Prevents the growth of abnormal new blood vessels.
  • Management of underlying conditions by controlling hypertension, diabetes, and high cholesterol is essential to prevent recurrence.

Retinal Artery Occlusion

  • Immediate intervention
    • Ocular massage: May help dislodge a blockage.
    • Lowering intraocular pressure: Through medications or paracentesis (removal of fluid from the eye).
  • Hyperbaric oxygen therapy (HBOT): Delivers high levels of oxygen to the retina, potentially restoring vision if started promptly.
  • Addressing underlying causes through treatment of carotid artery disease, atrial fibrillation, or other systemic conditions to reduce the risk of future occlusions.

Regular eye exams are crucial for early detection and prevention of vision loss from retinal vascular occlusions. Contact Retina Associates of Western NY to schedule your comprehensive retinal exam today.