A central retinal vein occlusion is a serious eye condition that causes sudden onset blurred vision. This is caused by a blockage in the blood vessels of the back of the eye. When the blood vessels are blocked, blood is unable to drain and can bleed in the retina tissue of the eye. It is important to have an eye exam immediately to begin treatment and monitor for the resolution of the central retinal vein occlusion.
Blood Vessels in the Eye
The eye is supplied with blood and nutrients by blood vessels that enter the back of the eye alongside the optic nerve.
These blood vessels are rather small in size due to the tight area in which they travel.
The retina and other structures of the eye rely on the blood from these blood vessels to obtain oxygen, nutrients and rid the waste from the tissues.
How a CRVO Occurs
A central retinal vein occlusion is often caused by a thrombus or blockage in the blood vessel.
The thrombus rarely originates from the small blood vessel in the eye, rather it is formed elsewhere in the body and travels in the bloodstream until it clogs the blood vessel of the eye.
The most common association between the formation of a thrombus and the occurrence of a CRVO is uncontrolled high blood pressure.
The blood pressure causes the blood vessels to weaken and alters the blood flow. This creates the opportunity for a thrombus to form in the blood vessel and then travel to the eye to cause a CRVO.
Types of CRVOs
There are two types of central retinal vein occlusions, there are perfused (non-ischemic) central retinal vein occlusions and non-perfused (ischemic) central retinal vein occlusions.
While both types cause the same blockage to the main blood vessel of the eye, the non-ischemic CRVO is much less severe than the ischemic CRVO.
A non-ischemic central retinal vein occlusion will only impact a limited amount of the retina and the blood vessels outside of the immediate blocked area will remain functional.
On the other hand, an ischemic central retinal vein occlusion has a much larger impact and reduces the function of blood vessels in a widespread area of the retina.
With more significant damage, an ischemic central retinal vein occlusion will also reduce vision much more and can lead to an afferent pupillary defect from the lack of vision in the affected eye.
Treatments for Central Retinal Vein Occlusion
A central retinal vein occlusion can reduce vision to very poor in a short amount of time, but usually, some of this vision can be regained.
The first step in managing a CRVO is to ensure that blood pressure and blood sugar are not continuing to cause problems by being consistently elevated.
After the blood pressure and blood sugar is controlled, the CRVO can be treated with an injection of anti-VEGF medication if there is associated swelling from the event.
There is a risk to develop glaucoma from the blood vessel growth that occurs as a CRVO heals so there should be regular follow-up visits scheduled to assess for this risk.