Eye Occlusions - Types, Symptoms & Treatment
Eye occlusions appear when blood flow through vessels supplying the eyes is altered by a blockage. This prevents oxygen and nutrients from reaching the ocular globes and may lead to vision impairments and even eye strokes if not treatment is applied in time.
The severity of vision loss is directly dependent on the extent and location of the blockage. Although all occlusions can cause serious sight problems, the most threatening complications appear when blood flow to the retina and optic nerve is compromised.
The four types of eye occlusions
Ocular occlusions can affect both veins and arteries so depending on their location these eye disorders can be classified into four different types: occlusions affecting the branch retinal artery, blockages of the central retinal artery, eye occlusions triggered by blockages of the branch retinal vein and central retinal vein occlusions.
Eye occlusions affecting the branch retinal artery (BRAO) are caused by blood clots coming from the carotid artery or from heart valves. Appearing suddenly, these blockages are painless and lead to an abrupt loss of peripheral sight when the blocked artery is near the retina or to complete vision loss, when the blocked blood vessels are located near the optic nerve.
BRAO are usually triggered by diabetes, hyperlipidemia, hypertension and atrial fibrillation (abnormal heart rhythm), older people being more prone to experiencing this vision disorder than younger ones.
BRVO (branch retinal vein occlusions) is generally linked with atherosclerosis so plaque and thrombi are most of the times responsible for the occurrence of this blockage. However, hypertension, aging, elevated levels of blood lipids, smoking and a history of glaucoma or stroke are also thought to increase the risks of developing BRVO.
Branch retinal vein occlusions are the most common type of occlusive disease affecting the eyes and their incidence is higher among diabetic people. Women and men are equally affected by this disorder, most of the time its onset being somewhere between 60 and 70 years.
The third category of occlusions, affecting the central retinal artery, is caused by clots or emboli from the carotid artery or heart, clots responsible for blocking blood flow to the retina. High blood pressure, carotid artery disease, diabetes and cardiac valves diseases are the most common risk factors for this form of eye occlusion.
CRVO (central retinal vein occlusion) is the last type of eye occlusions altering the blood flow in eyes. The cause is a clot formed inside the central retinal veins, which prevents blood from leaving the retina. As a result, fluid builds up inside the light-sensitive layer of the ocular globe responsible for processing images, leading to retinal injuries and vision loss.
Symptoms of eye occlusions
Although these blockages don’t have specific symptoms, they can be recognized based on some manifestations which appear once the blood vessels get blocked. People affected by BRAO experience a sudden and unexplainable loss of vision and increased blood pressure.
The typical symptoms for BRVO are blurred or distorted vision, peripheral sight loss and blind spots. Retina hemorrhages and fluid leakage are also common in patients dealing with this disorder.
For CRAO (central retinal artery occlusion), the specific manifestations are the sudden, painless vision loss affecting one eye, the pale retina and narrowed blood vessels. Last, CRVO is defined by macular edema, dilated veins in the retina and eye hemorrhages, optic disc edema and cotton-wool spots.
Treatments for eye occlusions
BRAO can be managed through carotid endarterectomy, a surgical procedure used for enlarging blood vessels and prevent stroke, or through anticoagulation. For CRAO, glaucoma medications, ocular massage and minor surgical procedures called anterior chamber paracentesis may reduce the symptoms, although no complete cure has been found yet.
Anticoagulants like coumadin, aspirin and heparin are recommended in the treatment of BRVO, although their role is to prevent complication and not to cure this condition. Laser therapies and anti-vascular endothelial growth factor injections appear to be effective as well. As for CRVO, the only valid treatment is usually surgery as laser treatment is not efficient in this eye disorder.