What is an embolism in the eye?
An embolism is a pathological event that leads to a blockage of blood vessels. The cause is usually a small blood clot (lat. thrombus).
However, air and fat embolisms can also occur in the eye – but fortunately they are very rare. The blockage of the blood vessel leads to a reduced supply of oxygen and other nutrients to the tissue. As a result, the tissue dies.
An embolism usually occurs in the small blood vessels that supply the retina. The damaged retina can no longer properly perceive the incoming light stimuli. This results in a loss of vision.
The cause
The causes of an ocular embolism are manifold and mostly systemic in nature. For example, increased coagulability of the blood can lead to increased formation of blood clots. These trigger small embolisms in many parts of the body.
Such an embolism is particularly noticeable in the eye, as the structures in the eye are very small. Even very small clots can lead to a blockage. The blood vessels can be blocked by even very small clots, and the retina’s ability to function quickly fails.
In addition, heart diseases also play an important role in the formation of blood clots. Cardiac arrhythmias cause small clots to form, which are washed into other organs by the bloodstream. Other causes of embolisms in the eye can also be inflammatory events – especially if the inflammation affects vessels near the eye, as in arteritis temporalis (inflammation of the temporal artery).
This is caused by the body’s immune response, which promotes the formation of blood clots. But also diseases of the eye itself, such as glaucoma (increased intraocular pressure) can cause embolisms. The pressure in the eye changes the flow of blood, it flows more slowly and can therefore clot in the vessel.
The accompanying symptoms
Embolisms in the eye mostly affect the retina of the eye. The retina does not have sensors that can perceive pain stimuli, so an embolism in the eye is usually not felt. As a rule, the embolism only becomes noticeable when parts of the retina are affected that are needed for vision.
There are many receptors in the retina that transmit signals to the brain when light falls on them. If the defect in the retina is too large due to the embolism, the brain notices that light signals can no longer be received at a certain point in the eye. Affected persons notice this by a loss of a small area of the visual field.
For example, objects and movements at a certain location can no longer be perceived. In the case of small defects, the brain is able to make up the missing image (usually only one eye is affected by an embolism and the brain receives information about the non-visible area from the second eye). Thus, it is often only when there are major circulatory disorders of the eye that severe limitations occur. These can lead, for example, to the loss of half or even the entire visual field in one eye. Since embolism in the eye is often a sudden process, it is essential to think about an embolism if you have an acute loss of vision and have this clarified by a doctor.
