A retinal vein occlusion is the sudden blockage of blood flow out of the eyeball, which causes macular bleeding, swelling, and loss of vision.
The retina is the part of the eye that receives light and transmits images to the brain. The eye requires a lot of energy to create vision, so there is a significant amount of blood flow bringing oxygen and nutrients to and from the retina. Two major vessels, called the central retinal artery and vein enter the eye through the optic nerve and branch over the surface of the retina. These vessels are the only source of blood flow for most of the inner retina.
As our retinal blood vessels age, they accumulate cholesterol causing hardening of artery walls. Our blood may also develop an increasing propensity to clot. Sometimes these factors combine in the eye to cause a sudden blockage of a retinal vein, which prevents blood flow from leaving the retina. The blockage, or ‘occlusion,’ results in reduced retinal blood flow, retinal bleeding, swelling, and sudden painless loss of vision.
Compare Central Retinal Vein Occlusion and a Branch Retinal Vein Occlusion
Retinal vein occlusion can be subdivided into two categories, depending at what point a clot forms along the network of blood vessels in the eye. A central retinal vein occlusion (CRVO) occurs when the single, large vein that drains blood from the inner retina becomes blocked. This usually occurs as the vein passes through the optic nerve on its pathway out of the eye. Because this vein is the only pathway for blood to leave the eye, hemorrhages form throughout the retina, blood flow is significantly reduced, and swelling throughout the center of the retina (macula) occurs.
Central retinal vein occlusions can be classified based on how much they restrict blood flow to the eye. Mild CRVO’s cause only minor disruption of vision and typically require fewer treatments to improve. Severe CRVO’s lead to profound loss of blood flow to the eye, which in turn requires intensive treatment to prevent severe vision loss.
In contrast to a CRVO, a branch retinal vein occlusion (BRVO) occurs when only a tributary of the main retinal vein is obstructed. This typically occurs at a point where a branch of the retinal artery and retinal vein cross each other along the surface of the retina. At this crossing point, the stiff-walled artery can press on the soft-walled vein, causing the vein to collapse and obstruct the blood flow through the vessel. The resulting hemorrhages and swelling within a section of the retina can harm vision, but do not affect the entire visual field like a CRVO.
What are the Risk Factors for Retinal Vein Occlusion?
The risk factors for a retinal vein occlusion include anything that increases the stiffness of artery walls or elevates the propensity for forming blood clots. Factors that lead to hardening of the arteries include all of the familiar cardiovascular risk factors for heart attack and stroke: Blood pressure, cholesterol, diabetes, smoking, diet, exercise, weight, and family history. In younger patients, the propensity to form blood clots can be elevated by risk factors such as smoking, estrogen use, inherited clotting disorders, autoimmune conditions, and cancer.
In patients over the age of 50, the most common causes for retinal vein occlusion are cardiovascular risk factors. These folks should be sent for a primary care doctor evaluation of their blood pressure, cholesterol, blood sugar, and counseling regarding their cardiovascular risk profile. Anyone who experiences a retinal vein occlusion under the age of 50 should also be evaluated for clotting disorders, autoimmune conditions, and blood disorders including cancer.
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What are the Symptoms of a Retinal Vein Occlusion?
A retinal vein occlusion causes a sudden, painless blurring of vision in one eye. While a central retinal vein occlusion blurs all of the central vision, a branch retinal vein occlusion may only affect the upper visual field or lower visual field. The blurriness from retinal vein occlusion will not fluctuate, but rather persist for months or years if not treated promptly.
How is a Retinal Vein Occlusion Diagnosed?
If you suspect that you may have a retinal vein occlusion, seek a dilated examination with and ophthalmologist specialized in macula and retina conditions. During your visit, you will undergo specialized imaging that can evaluate whether retinal swelling is causing vision loss. The ophthalmologist will examine your retina and discuss treatment options with you.
If you are under the age of fifty or suspected to have an underlying systemic cause for your retinal vein occlusion, you may be sent for further laboratory testing or imaging. All patients who experience a retinal vein occlusion should have regular follow-up with their primary care doctor to monitor and treat cardiovascular risk factors.
How is Retina Vein Occlusion Treated?
A retinal vein occlusion is most commonly treated with injections of medicine into the eye. The medicine is specifically targeted to treat swelling of the retina, which can restore and protect central vision. While the injections have to be repeated every 4-12 weeks over months or years, they have been proven to prevent severe vision loss that can occur without treatment.
Sometimes, a retinal vein occlusion may be treated with laser. Typically, the laser is used in cases where injections are ineffective (rare) or when there is new blood vessel growth in the retina that can cause bleeding, glaucoma, or retinal detachment. While there are no surgeries to remove clots from a retinal vein, occasionally the surgical removal of blood from the eye is warranted.
Lastly, retinal vein occlusions that occur without symptoms, happen outside of the center of vision, or don’t cause retinal swelling can be safely monitored without treatment.
What is the Prognosis for a Retinal Vein Occlusion?
With appropriate and timely treatment, excellent vision can be achieved even after a retinal vein occlusion. Conversely, the most common cause for poor vision after a retinal vein occlusion is delay in diagnosis or treatment. Even in some cases of excellent follow-up however, the retinal vein occlusion is unresponsive to medical treatment due to severely reduced blood flow to the retina.
If you or a loved one are experiencing changes to your vision, you need to talk to a professional immediately so that it doesn’t get worse. Do not hesitate to call us today at (941) 351-1200. We can help you!
At Retina Care Consultants, P.A., we specialize in retinal vein occlusion treatment. Our team of experts has years of experience treating all types of retinal and macular conditions. We’ll find the right treatment for your needs and prevent further complications that could come as a result of the vein occlusion. Our thorough exam may involve dilation, blood tests, photographs, or other specialized imaging of the retina.
Contact Us At Retina Care Consultants, P.A.
There are effective ways to treat all forms of vein occlusion, so don’t delay your appointment if you are experiencing sudden, painless loss of vision in Sarasota, Bradenton, or Lakewood Ranch. If left untreated, vein occlusions can lead to glaucoma (intense eye pressure) and macular edema. Contact us today to get high-quality retinal vein occlusion treatment at one of our locations in Sarasota and Manatee County.
Retina Care Consultants specializes in Macular Degeneration, Flashes and Floaters, Intravitreal Eye Injections, and many more conditions of the retina. We treat patients from the Sarasota, Bradenton and Lakewood Ranch areas of Florida.