The vitreous body is an integral part of the eye that fills the entire posterior chamber of the eye. Normal ageing processes, degenerative changes, inflammation or even bleeding can lead to various changes and diseases of the vitreous body.
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The vitreous body (corpus vitreum) is an integral part of the eye in all vertebrates. It fills the entire posterior chamber of the eye and is responsible for maintaining the shape of the eyeball.
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The structure of the eye @ bilderzwerg /AdobeStock
Inside the eye is the vitreous body (corpus vitreum), which has a spherical and transparent structure. It is bordered by the lens at the front and the retina at the back . It is located in the posterior chamber of the eye (posterior chamber).
The vitreous body consists of 98 percent water and has a jelly-like consistency. The mass contains neither nerves nor blood vessels. Clinically, doctors can sometimes detect a vestigial remnant of the embryonic artery.
During the embryonic phase, this blood vessel transports all substances into the eyeball that are necessary for the development of the eye. The hyaloid artery only regresses towards the end of embryonic development. It remains in the vitreous body as Cloquet's canal until the end of life.
After the eye refracts and focuses light rays at the cornea and lens according to the angle of incidence , they pass through the vitreous body. The light rays then fall on the retina, which lies behind the vitreous body and has photoreceptors.
These receptors convert the light stimuli into electrical signals. This is where a very complex signal cascade begins, which extends to the central nervous system. The brain then interprets the signals as images.
An important prerequisite for the unhindered irradiation of light rays onto the retina is the transparency of the vitreous body.
Various processes can lead to changes in the vitreous body.
These are, for example
In order to diagnose a disease, the pupil needs to be dilated with medication. This allows the ophthalmologist to examine the vitreous body and retinal choroid structures with a magnifying glass or contact lens. As driving is prohibited with a dilated pupil, you should always visit the ophthalmologist without a car.
Annoying but simple opacities of the vitreous body often do not require treatment, as these opacities subside within the vitreous body. Those affected usually no longer notice them. They have no effect on vision.
Other causes such as retinal tears, inflammation and vitreous hemorrhage require treatment. Only in rare cases is surgical removal of the vitreous body (vitrectomy) necessary.
The majority of physiological and pathological changes to the vitreous body are characterized by floccular or mosquito vision.I
"Mosquito vision" of the eyes
These opacities are manifested by grayish-transparent and indistinct double contours that slowly glide around and move with the gaze.
Colloquially, they are also known as mouches volantes (flying gnats), which are actually only part of the vitreous opacities. The opacities can be seen more clearly when looking at bright areas (white wall, sky).
Visual acuity is not affected. Almost all patients feel disturbed at first, but learn to live with it over time.
Vitreous opacities are generally harmless and occur in many people. There is no particular pathological value, which is why they do not require treatment.
If patients feel too disturbed, laser treatment can help. Surgical removal of the vitreous humor is rarely necessary.
The doctor should weigh up the risks and benefits together with the patient before the procedure. If the visual acuity is significantly reduced or the situation is stressful for the patient, such an operation may be advisable.
As a general rule, you should have any uncertainties regarding vitreous opacity examined by a doctor. They can rule out serious illnesses and prescribe appropriate treatment.
In the course of life, the vitreous body detaches from the retina. Doctors refer to this process as vitreous detachment. The cause is an increasing liquefaction of the vitreous followed by a consecutive detachment from the retina. Vitreous detachment is an age-related process that affects all people. Normally, no serious complications are to be expected.
The detachment causes the posterior limiting membrane of the vitreous body to shift in front of the retina. As a result, opacities become visible at this limiting membrane.
These and those caused by condensation of the central vitreous body are perceived by those affected as ring- or snake-shaped lines. This is why experts also refer to them as flying gnats. These gnats move with the eye movements.
A side effect of vitreous detachment can be
This is an absolute emergency that doctors usually have to treat within a few hours. If a detached retina is not surgically reattached, this leads to blindness.
Rapid treatment is important for retinal detachment @ bilderzwerg /AdobeStock
Vitreous opacities accompanied by many black dots and seeing flashes can be the first signs of retinal detachment.
In this case, you should consult an ophthalmologist or an eye clinic immediately. If the retinal detachment progresses, a black shadow appears that moves from the outside to the center of the visual field.
As it progresses, blindness occurs in the affected eye. A sudden appearance of black dots or streaks can be a differential diagnosis for bleeding in the vitreous body.
In around 30 to 40 percent of cases of vitreous hemorrhage, there is also a defect in the retina.
Small hemorrhages in the vitreous body can be caused by various things, such as
A vitreous hemorrhage can also occur during a subarachnoid hemorrhage(Terson's syndrome).
Depending on the size of the hemorrhage, it may be noticeable as a rain of ash.
Vitreous destruction (destruction of the vitreous body) is an age-related process in which the vitreous body liquefies. This leads to a separation of the liquid and fibrous components of the vitreous body. This can result in clouding of the vitreous body, which those affected perceive as annoying flying gnats.
Vitreous humor inflammation (vitritis) can occur both chronically and acutely. Inflammation of the vitreous body is rather rare due to its structure and vascular supply , but not impossible. The worst form of inflammation is endophthalmitis, in which other parts of the inside of the eye are also affected.
Bacteria, viruses and fungi are possible causes of vitreous inflammation:
These can enter the vitreous in the following ways:
Patients with no significant underlying disease usually suffer from bacterial vitreous inflammation. Patients with immunodeficiency (AIDS patients, patients with tumors, patients after an organ transplant) can also suffer from fungal vitreous inflammation (Candida species).
In addition to direct transmission routes, indirect transmission (sepsis) can also occur.
Depending on the type of pathogen and the patient's immune system, doctors speak of acute, subacute or chronic vitreous inflammation.
Acute vitreous humor inflammation usually manifests itself in the patient as dull pain in the eye. Painkillers cannot usually suppress this pain. Inflammation of the vitreous body also causes the conjunctiva to become very red.
Chronic vitreous inflammation is usually less severe.
The doctor treats the disease based on the cause. If the inflammation of the vitreous humor is due to certain pathogens, treatment is based on an antibiogram.
In synchisis scintillans (spark vision, spintheropia, Danziger Goldwasser), cholesterol crystals are deposited in the vitreous body.
In addition to cholesterol deposits, the amino acids tyrosine and leucine as well as calcium phosphate can form crystals in the vitreous. These lead to this side-unequal disease.
Synchisis scintillans and asteroid hyalosis are easy to confuse. Synchisis scintillans occasionally occurs after bleeding or inflammation of the vitreous. In most cases, however, the cause is unknown.
Persistent hyperplastic primary vitreous (PHPV)
The term PHPV (persistent hyperplastic primary vitreous) refers to a congenital malformation. In this case, the embryonic primary vitreous body has not regressed. Experts therefore refer to this phenomenon as a developmental disorder. However, it is a very rare disorder.
There are two different forms of PHPV:
In the posterior form of PHPV, the embryonic tissue remains in the posterior region.
In the anterior form of PHPV, a plate of connective tissue develops that is whitish in color. This is located behind the pupil, so that those affected perceive a white pupil(amaurotic cat's eye).
Changes occur in the lens. Fatty tissue and cartilage also form in the area of the lens.
Posterior PHPV can lead to a loss of visual acuity. This depends on the severity of the retinal detachment. In anterior PHPV, the lens can develop into a cloudy membrane.
The loss of vision is often unavoidable with a persistent hyperplastic primary vitreous. Despite surgical intervention, doctors can often only preserve the eye.
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