Retinal Vein Occlusion

Overview

Retinal vein occlusion occurs when one of the veins that carry blood away from the retina becomes blocked, usually by a blood clot. The retina is the light-sensing layer at the back of the eye, and when its drainage is obstructed, blood and fluid back up and leak into the retina. This swelling, especially in the central macula, blurs or reduces vision, often suddenly and without pain.

There are two main types. In branch retinal vein occlusion, a smaller vein is blocked and only part of the retina is affected. In central retinal vein occlusion, the main vein is blocked and a larger area is involved, usually causing more severe vision loss. Retinal vein occlusion is one of the more common causes of sudden vision loss in older adults and shares many risk factors with heart and circulation problems, so it warrants prompt eye and general medical evaluation.

Symptoms

Symptoms usually affect one eye and develop suddenly, often noticed on waking. They include:

• Sudden, painless blurring or loss of vision in one eye
• A dark or missing area in part of the visual field
• Distorted vision, with straight lines appearing wavy
• New floaters in some cases
• Vision that may fluctuate, especially early on

The degree of vision loss ranges from mild blurring to severe loss depending on the type and extent of the blockage. Sudden vision loss in one eye is a warning sign that needs prompt evaluation by an eye doctor, as it can also be caused by other serious conditions that require urgent treatment.

Causes

Retinal vein occlusion happens when blood flow through a retinal vein is blocked, most often by a clot. This is usually related to changes in the blood vessels and blood flow rather than a single cause. Contributing factors include:

• Atherosclerosis: a nearby stiffened artery can press on and narrow the vein where they cross.
• Slowed or turbulent blood flow: which makes clotting more likely.
• High pressure in the eye: as occurs in glaucoma.
• Blood-clotting disorders: certain conditions that make the blood more likely to clot, especially in younger patients.
• Inflammation of blood vessels: in less common cases.

The same vascular risk factors that affect the heart and brain also affect the small vessels of the eye.

Risk Factors

Risk increases with conditions that affect blood vessels and clotting. Common risk factors include:

• High blood pressure, the most common associated condition
• Diabetes
• High cholesterol and atherosclerosis
• Glaucoma or high eye pressure
• Older age
• Smoking
• Blood-clotting disorders, more relevant in younger people

Diagnosis

An eye doctor diagnoses retinal vein occlusion through examination and imaging, and often arranges general medical testing for underlying conditions. Tests include:

• Dilated eye examination: to view the retina, where blocked veins, bleeding, and swelling are visible.
• Optical coherence tomography (OCT): to measure retinal swelling, especially in the macula.
• Fluorescein angiography: a dye test that shows blood flow and areas where circulation is poor.
• Eye pressure measurement: to check for glaucoma.
• Blood pressure and blood tests: to identify high blood pressure, diabetes, cholesterol, or clotting problems.

Treatment

Treatment aims to reduce retinal swelling, protect vision, and prevent complications, while managing the underlying risk factors. Options include:

• Eye injections: medications injected into the eye to reduce macular swelling and abnormal blood-vessel growth, often the main treatment.
• Laser treatment: used for persistent swelling or to treat areas of poor circulation that can lead to dangerous new vessels.
• Managing risk factors: controlling blood pressure, diabetes, and cholesterol, and treating glaucoma.
• Monitoring for complications: regular follow-up to watch for new blood-vessel growth and a serious form of glaucoma that can follow.

Vision outcomes vary. Some people regain much of their vision, while others, especially with severe central occlusions, have lasting loss. Early treatment improves the chances of preserving vision.

Prevention

Lowering vascular risk factors is the best way to reduce the chance of retinal vein occlusion and protect the other eye. Helpful steps include:

• Keeping blood pressure under good control
• Managing diabetes and cholesterol
• Not smoking
• Staying physically active and maintaining a healthy weight
• Having regular eye examinations, especially if you have glaucoma or diabetes
• Following up on any blood-clotting disorders

When to See a Doctor

Seek prompt, same-day eye care for any sudden loss or blurring of vision in one eye, even if it is painless. Sudden vision loss can be caused by retinal vein occlusion or by other serious conditions, including a blocked retinal artery, which is a true emergency.

Seek emergency care if vision loss is accompanied by sudden severe eye pain, a fixed dark curtain across your vision, or stroke-like symptoms such as facial drooping, arm weakness, or slurred speech, which require calling emergency services immediately.

Related Topics

Frequently Asked Questions

References

1. American Academy of Ophthalmology. Retinal Vein Occlusion.
2. National Eye Institute (NEI). Retinal Diseases.
3. MedlinePlus, U.S. National Library of Medicine. Retinal vein occlusion.
4. Mayo Clinic. Retinal diseases — Symptoms and causes.