Did you know that the blood vessels in the eye could be occluded (or obstructed), similar to what occurs in a stroke? In other words, our eye may suffer a ‘stroke’ if the blood vessels are blocked, especially in the case of atherosclerosis, hypertension and high cholesterol.
Vascular occlusions simply refer to blocked or obstructed blood vessels. These vascular occlusions can occur not only in the eye but also in the retina. The retina is a particularly important part of the eye, housing the special light sensitive cells that capture the light and transmit it as signals to your brain to achieve sight. As with any living part of the body, the cells in the retina require a supply of nutrients and oxygen. This supply of essentials takes place through the vascular system, where blood carries these much needed nutrients and oxygen to the retinal cells.
It is however, very possible for the blood vessels that carry blood to and from the retina to be blocked or obstructed. This can be due to a blood clot, or a variety of other reasons. This situation of a blockage is hence known as an occlusion.
This occlusion may lead to buildup of blood and other fluids in the area, or at the macula. When this happens the retina’s ability to function properly may be affected. In certain cases, the occlusion grows large enough to obstruct light that enters the eye. This results in a loss of vision. The severity of vision loss is dependent on the site of which the occlusion occurred, size of the occlusion and whether other complications have taken place.
Retinal vascular occlusions can be potentially serious. The site of the blockage causes a buildup of pressure due to the constant supply of blood to the site. Without an outlet to drain the collected blood, the blood vessel may burst and surrounding structures may be damaged. The situation can be exacerbated by bodily conditions such as atherosclerosis – a hardening of the arteries, which can further increase the risk of serious complications.
Retinal Vascular Occlusions mainly fall into 2 categories, and this depends on the type of blood vessel the occlusion takes place at:
A retinal artery occlusion occurs when one of the arteries supplying blood to the retina becomes blocked. Retinal arteries are responsible for transporting oxygen-rich blood from the heart to the retinal cells, which is essential for their survival and proper function.
The main artery supplying the retina is the central retinal artery, which further branches into smaller retinal arteries as it nears the retina. An occlusion can occur either in the central retinal artery or in one of the smaller branch retinal arteries, potentially leading to serious vision impairment if blood flow is disrupted.
The other form of retinal vascular occlusion occurs in a different set of blood vessels within the retina—the retinal veins. Unlike arterial blood, which is rich in oxygen, blood in the retinal veins is deoxygenated. After delivering oxygen from the lungs to the retinal cells, the blood collects metabolic waste and returns to the heart, where it continues its circulation throughout the body.
Retinal vein occlusion can affect either the central retinal vein or the smaller branch retinal veins, leading to impaired blood flow and potential vision problems.
It should be noted that occlusions that happen in the main retinal vein or artery are considered more serious than occlusions that occur in the branch veins and arteries.
The exact cause of retinal vascular occlusions remains unclear. However, one possible contributing factor is the narrowing of retinal veins due to atherosclerosis, which may increase the likelihood of a blockage. Additionally, various systemic conditions that affect blood circulation can elevate the risk of developing a retinal vascular occlusion. Some of these key risk factors include:
The most noticeable symptom of a retinal vascular occlusion is a sudden and significant change in vision. This may present as blurry vision, partial vision loss, or even complete blindness in the affected eye.
Key Characteristics of Retinal Vascular Occlusion Symptoms are that it usually occurs in one eye only. The condition does not “spread” to the other eye. It is experienced as painless vision loss. Unlike some other eye conditions, retinal vascular occlusions do not cause pain. If pain is present, another underlying condition may be responsible.
The earlier treatment is sought, the higher the chance of reversing or managing symptoms. If you experience a sudden and drastic change in vision, contact your eye doctor, eye specialist, or ophthalmologist immediately. In cases of partial or complete vision loss, seek urgent medical attention at the nearest hospital.
Retinal artery occlusions are more severe and can lead to sudden and irreversible blindness in the affected eye. Retinal vein occlusions, while serious, may be treatable if diagnosed early.
The best way to reduce the risk of another occlusion is to manage underlying conditions such as high blood pressure, hypertension, or high cholesterol. Without proper control, a second vascular event could occur, affecting the other eye, heart (heart attack), or brain (stroke). Early medical intervention is key to preserving vision and overall health.
Vein occlusions may be treated with eye injections which can improve the vision dramatically. Sometimes continuing eye injections may be necessary to maintain the good vision of the affected eye, which could be considered a small price to pay for ensuring useful vision in a ‘stroke’ eye.
