Retinal artery occlusion: what is it and why does it occur?
Retinal artery occlusion is a common pathology that affects sight. The retinal artery it is one of the blood vessels responsible for supplying oxygenated blood to the retina.
The retina, for its part, is a fundamental part of the eye. It interprets the light stimuli and makes them nervous. These travel through the optic nerve to the brain, where they are interpreted.
Therefore, when a retinal artery occlusion occurs the sense of vision is often severely impaired. It can cause blindness. In this article we explain everything you need to know about the pathology and how it is treated.
What is retinal artery occlusion?
Retinal artery occlusion, as we have mentioned, is a frequent and serious pathology. It refers, in particular, to plugging of the central retinal artery. As explained in an article by the Ophthalmological Society of the Valencian Community, it causes painless vision loss that usually occurs in only one eye.
Numerous arteries can be affected by an occlusion. Therefore, it is convenient to differentiate between the central retinal artery and the branch artery. The central one is more serious than the other.
When this pathology appears it is essential to act quickly. Most cases are associated with an atherosclerosis process or embolism. What you have to try is to reestablish the blood flow of the retina. Otherwise, if the interruption is maintained for more than 24 hours, it is very likely that the tissue will be irreparably damaged.
What are your symptoms?
Retinal artery occlusion is characterized by sudden loss of vision. It is usually painless and affects only one eye. In some cases, the loss of vision may be just a visual field defect (a part of the visual field is lost and not completely).
However, in other situations blindness is total. As the MSD Manual explains, when the occlusion has occurred acutely, very typical signs can be seen when performing ophthalmoscopy.
This is a test that allows you to look inside the eye. What is perceived is that the fundus is pale and opaque, with a cherry-red spot. If the cause has been a plunger, it is even possible that it can be seen.
It is also important to explore the reaction of the pupils to light. The pupil of the affected eye tends to be unresponsive when light is applied directly. However, it does contract adequately when illuminating the other eyeball.
Causes of retinal artery occlusion
The most common causes of retinal artery occlusion are embolism and atherosclerosis. Embolism is a thrombus originating in another part of the body that travels with the bloodstream. When it reaches a point where the vessels are narrower, the thrombus cannot move forward and obstructs.
In the case of retinal artery occlusion, it is this vessel that is obstructed by the embolus. The thrombus usually comes from the internal carotid artery. In fact, it is likely to be the consequence of an atherosclerotic process.
What happens is that part of the cholesterol plaque is detached. The thrombus follows the course of the carotid artery that branches to give rise to the retinal artery. There it interlocks and causes the interruption of the flow.
On the other hand, atherosclerosis is a very common disease that leads to progressive narrowing of the arteries. It is produced by the presence of atheroma plaques composed of cholesterol deposits and other particles.
Plaques occupy the lumen of the arteries. As they grow, the diameter decreases. That is why there comes a time when the obstruction is so great that blood cannot flow properly.
We have just seen that the main causes of retinal artery occlusion are atherosclerosis and embolism. These pathologies, in turn, present a series of factors that increase the risk of suffering them.
According to an article in the American Academy of Ophthalmology, men are more prone to occlusion than women. Also, the incidence increases as you get older. Specifically, the highest incidence peak is between 60 and 70 years of age.
On the other hand, smoking and high blood cholesterol increase the risk of retinal artery occlusion. The same goes for high blood pressure, cardiovascular disease and diabetes..
Blood disorders, especially those related to clotting, also act as aggravating factors. Vasculitis, which is inflammation of the blood vessels, can be considered a risk factor.
How is it diagnosed?
In order to diagnose retinal artery occlusion, it is essential to carry out a good examination and medical history. Vision loss, as we have seen, is usually unilateral, acute and painless. Therefore, it is the first indication to suspect it.
In addition, there are a number of tests that help confirm the diagnosis. For example, the fundus. It usually appears opaque and pale, instead of the arteries near the retina being visualized normally.
Fluorescein angiography is another of the most useful tests. Fluorescein is a contrast substance that is injected into blood vessels. With this method it is observed that the affected artery does not stain.
Other tests may be done to find out what caused the occlusion. Especially if a stroke is suspected. Thus, by means of Doppler ultrasound of the carotid arteries, it can be ruled out whether or not there is a focus of thrombi in them.
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Treatments for retinal artery occlusion
Retinal artery occlusion is a medical emergency. According to a study published in the Canarian Ophthalmology Society, management must be multidisciplinary. That is, both the condition and the cause must be treated. Spontaneous improvement is very rare.
Treatment must be started within 24 hours of evolution of the occlusion. Drugs that help reduce intraocular pressure, such as acetazolamide or topical timolol, can be used.
Some physicians recommend using thrombolytic approaches. That is, drugs that help dissolve the thrombus that is causing the occlusion. The problem is that they are not very effective in improving visual acuity.
An attempt may also be made to remove the plunger or some of the fluid in the eye to promote the clot displacement from the site of the obstruction. However, many patients do not regain the quality of vision.
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Retinal artery occlusion is an emergency
Retinal artery occlusion presents as a sudden, painless loss of vision that affects only one eye. It is more common in older men with cardiovascular risk factors. For example, high cholesterol or high blood pressure.
This pathology must be treated urgently. Even so, in many cases it is difficult for vision to fully recover. For this reason, it is essential that in the event of any symptoms, you always go quickly to the doctor to minimize the damage.