Retinal Artery Occlusion


OVERVIEW

A retinal artery occlusion occurs when the central retinal artery or one of the arteries that branch off of it becomes blocked. This blockage is typically caused by a tiny embolus (clot) in the blood stream. The occlusion decreases the oxygen supply to the area of the retina nourished by the affected artery, causing permanent vision loss.

Loss of visual acuity with this disorder will depend mostly on whether there is disruption of arterial blood flow to the macula or significant macular edema (swelling) is present.

Causes and Risk Factors: Retinal arteries can become blocked by a blood clot or substances (such as fat or plaque) that get stuck in the blood vessels. This is usually caused by an underlying disorder such as glaucoma, hypertension, diabetes, coagulation disorders, atherosclerosis, or hyperlipidemia.

In retinal artery occlusions, there is considerable visual loss. The degree of loss is partly related to the location of the occlusion. People with retinal vessel occlusion have a risk of stroke because the source of the clots (emboli) affecting the eye could also send clots to the brain. Retinal vessel occlusion more frequently affects older people. Risk factors are related to the possible disorders that cause the blockage.
 

              Branch Artery Occlusion                              Central Artery Occlusion

SIGNS & SYMPTOMS:

Central artery occlusion
Transient loss of vision prior to the artery occlusion (in some cases)
 
Central artery occlusion
Sudden, painless and complete loss of vision in one eye

Branch artery occlusion
Sudden, painless, partial loss of vision in one eye





DIAGNOSTIC TESTING:

  Retinal examination
  Visual acuity
  Slit lamp examination
  Ultrasound
  Optical Coherence Tomography
  Fluorescein Angiogram




 
TREATMENT

Treatment focuses on increasing blood flow to the retina, while trying to dislodge the thrombus or embolus from the blocked artery. Options include:

Ocular massage � The doctor uses his or her finger to apply pressure to your eye through your closed eyelid.

Breathing carbogen � By breathing this mixture of 95% oxygen and 5% carbon dioxide, you may be able to increase the flow of blood and oxygen to your retina.

Rebreathing carbon dioxide � Ifcarbogen is not available, the doctor may ask you to breathe into a paper bag to increase the amount of carbon dioxide in your blood. The increased level of carbon dioxide should dilate (widen) the arteries in your retina, increasing blood flow.

Anterior chamber paracentesis � An eye specialist uses a needle to remove a few drops of fluid from inside your eye. This decreases the pressure within your eye, making it easier for blood to flow through your retinal artery.

Experimental therapies � These include injection of a clot-dissolving medication directly into the eye's circulation, administration of vasodilators (medications that widen blood vessels), exposure to hyperbaric oxygen and destruction of retinal emboli with lasers.

In rare cases, when retinal artery occlusion is caused by temporal arteritis rather than a thrombus or embolus, treatment involves long-term treatment with high-dose corticosteroid medications.
The following conditions increase the risk of problems that may affect the vessels of the eye:

� High cholesterol
� Heart disease
� Arteriosclerosis
� Hypertension
� Diabetes
� Glaucoma