Definition

Retinal vein occlusion occurs when the blood vessels in the eye become blocked, leading to sudden vision loss without associated pain or redness. This condition affects approximately 5.2 per 1,000 individuals.

Causes

Retinal vein occlusion can arise from three primary causes, they are damage of blood vessels, slowed blood flow, and excessive blood clotting ability (hypercoagulability). Diseases such as hypertension and diabetes mellitus, as well as inflammation of blood vessels (vasculitis) caused by infections like syphilis, can damage blood vessels. Conditions like polycythemia vera, which involves an overproduction of red blood cells, and blood cancers such as lymphoma and leukemia, can slow blood flow. Meanwhile, hypercoagulability can be due to abnormalities in blood plasma proteins, autoimmune diseases like systemic lupus erythematosus, and the use of contraceptive pills, among other factors.

Risk Factor

The primary risk factor for retinal vein occlusion is advanced age, with 90% of cases occurring in individuals over 55. Another significant risk factor includes hypertension, especially untreated hypertension, which is present in 73% of patients over the age of 50. Hyperlipidemia or high levels of fat in the blood, marked by elevated cholesterol, regardless of age, is one of the risk factors. Diabetes mellitus is the risk factor that can exacerbate conditions like hypertension, increasing the risk of retinal vein occlusion.

The use of contraceptive pills can be a risk factor, particularly in young women. Besides these factors, smoking can increase the risk of retinal vein occlusion.

Symptoms

The hallmark symptom of retinal vein occlusion is sudden vision loss without pain or redness of the eye, often described as blurred or disturbed vision. These symptoms typically occur in isolation. If accompanied by numbness, decreased eye movement, muscle weakness, slurred speech, or drooping eyelids, another cause of vision loss is likely.

Diagnosis

Retinal vein occlusion can be confirmed through a series of examinations. The doctor will typically assess eye function, including visual acuity and light reflexes. Visual acuity might not be fully corrected with glasses or contact lenses, but the closer it is to normal, the better the ocular condition. The visual field may also be tested, as it can be affected if the eye tissue lacks oxygen due to venous occlusion.

The doctor will perform both direct and instrumental eye examinations. Direct examination might reveal red eyes, suggesting an advanced stage of the condition. Using a slit lamp, the doctor can inspect the iris for new, fragile blood vessels. Gonioscopy might also be performed to detect abnormalities in the corners and forepart of the eye.

To examine the ocular interior, a funduscopy is used to visualize the blood vessels and check for hemorrhages. Retinal vein occlusion often presents a "blood and thunder" appearance with bleeding and tortuous blood vessels, and may show swollen optic nerve endings due to blood accumulation.

Additional tests may include fluorescein angiography, which uses a dye and X-rays to examine the ocular blood vessels, and optical coherence tomography (OCT) if there is optic nerve swelling. This helps identify oxygen deprivation in the optic nerve caused by retinal vein occlusion.

Other examinations to identify risk factors for vein occlusion may include blood pressure measurement, erythrocyte sedimentation rate (ESR), complete peripheral blood examination (DPL), random blood sugar (GDS), total cholesterol, kidney and heart function tests. Tests for syphilis and protein abnormalities may be conducted if indicated.

Management

Management of retinal vein occlusion is decided according to the underlying causes and focuses on preventing complications. The treatments may include medications to reduce blood clots. For treating the swelling of the optic nerve, medications can be prescribed to prevent the formation of new blood vessels.

Surgery is aimed at destroying blockages, connecting veins to improve blood flow, or performing vitrectomy (removal of the vitreous fluid and replacement with another fluid).

Given that retinal vein occlusion often occurs alongside risk factors like hypertension, diabetes mellitus, and hyperlipidemia, adherence to medication and lifestyle changes is crucial. Recommended lifestyle improvements include eating a balanced, healthy diet, exercising for 30-50 minutes every two days, and maintaining a normal body weight.

After the treatments, vision sharpness may improve but typically does not return perfectly to its pre-occlusion state. The extent of recovery is dependent upon the initial visual acuity at symptom onset. Consequently, doctors often recommend monitoring for up to six months following the appearance of symptoms.

Complications

Retinal vein occlusion can lead to oxygen deprivation in the ocular nerve tissue, prompting the release of vascular endothelial growth factor (VEGF). This triggers the formation of poor-quality new blood vessels that grow in inappropriate places and are prone to rupture. Without treatment, this can result in optic nerve swelling, intraocular bleeding, and glaucoma due to new blood vessels. Optic nerve swelling can exacerbate vision loss caused by venous occlusion, and glaucoma can develop if new blood vessels obstruct fluid drainage in the forepart of the eye.

Prevention

Preventing retinal vein occlusion involves managing risk factors like hypertension, diabetes mellitus, and hyperlipidemia through a healthy diet and regular physical activity. Adherence to therapy is crucial for those with existing risk factors to maintain controlled blood pressure, blood sugar, and cholesterol levels, thereby preventing retinal vein occlusion.

When to See a Doctor?

If you experience sudden vision blurring or loss that does not improve, seek medical attention immediately. Prompt treatment of retinal vein occlusion enhances the chances of a near-perfect recovery.

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