Retinal vessel occlusion is a blockage in one of the tiny veins or arteries that supply the retina - the layer of light-sensitive cells lining the back surface of the eye.
Occlusion of the retinal artery is a sight-threatening emergency. If blood flow is not re-established within a few hours, death of the light-sensitive cells produces permanent loss of vision in the affected eye.
Blockage may be due to a blood clot, or more often, an embolus from a blood clot or a fragment of atherosclerotic plaque that has broken away from the site of its origin and has been carried by the bloodstream to lodge in an artery.
An embolus lodged in the main retinal artery or one of its branches will cut off the blood supply to the affected eye. By contrast, retinal vein occlusion is not a medical emergency, and there is no effective treatment. However, because blood cannot escape form the blocked vein, it may seep into the vitreous humor, the transparent, jellylike substance that fills the eye, clouding the vision of the affected eye. The vision may clear spontaneously or remain permanently clouded.
Glaucoma, diabetes mellitus, hypertension, or an increased blood viscosity can be predisposing factors. A blood clot, an embolus composed of a blood clot or atherosclerotic plaque, or cancerous cells may block a retinal blood vessel.
Retinal vessel occlusion is more common among the elderly.
Symptoms of retinal vessel occlusion occur suddenly with abrupt, painless vision loss. Treatment is sometimes initiated even before diagnosis is complete, since quick action may save the retina in some cases. Unfortunately, partial loss of vision is rarely prevented even with prompt treatment.
There is no generally accepted medical therapy. Involution of secondary retinal neovascular overgrowth by photocoagulation may decrease vitreous hemorrhages. Secondary neovascular glaucoma requires panretinal photocoagulation.
Other treatment measures include:
- Breathing into a paper bag to increase the amount of carbon dioxide in the blood may permit the arteries to dilate or widen, releasing the blockage
- A doctor may apply firm, intermittent pressure to the eye with the heel of the hand (pressing on the eye for a few seconds, suddenly releasing the pressure, then repeating the procedure), to try and dislodge the blockage
- Anticoagulant drugs, such as aspirin, heparin, or warfarin, may be administered to prevent further clot formation
- Ophthalmologists may use other special procedures to clear the blockage
- Antihypertensive drugs may be prescribed to treat associated high blood pressure
Is there a blockage in the retina?
Is it in an artery or vein?
How serious is this?
What is the probable cause?
Is there a problem with the blood pressure?
What treatment do you recommend?
Is there a risk of losing sight?