Introduction
Nearly everyone can recognize small black dots, fluff or threads when they look at a white wall, the sky or white paper, which other people present cannot see. These spots in the field of vision move flittingly together with the line of sight. They are called “flying mosquitoes” (Mouches volantes).
They are caused by clouding of the vitreous body. Depending on the degree of impairment, they are typified or classified according to severity, but there is no uniform categorization of vitreous opacities. At the beginning of life the vitreous body is a homogeneous mass, which in the course of life is increasingly interspersed with fibrous parts or fluid-filled cavities.
These fibrous portions are formed by the condensation of macromolecules on the collagen fibers in a physiological way. The water previously bound to the molecules is released and the vitreous body thus becomes liquid. In the course of this change, the vitreous body shrinks and detaches from the retina in the posterior region.
The fibrous parts distribute themselves freely in the eye, and when light irradiation is particularly high, they cast shadows on the retina, the already mentioned “black spots”. The perceived dots and striae are therefore not an illusion. Mouches volantes are especially strong when the irregularities are close to the retina. If the destruction of the vitreous body is already far advanced, the mouches are perceived against any background and even with closed eyes.
The glass body
The vitreous body in the eye is responsible for keeping the eye in its shape. The gel-like, transparent mass lies between the lens of the eye and the retina, which is why light must pass through the vitreous body to reach the retina. The vitreous body consists mainly of water (98%), collagen fibers and hyaluronic acid (2%).
The latter is responsible for the gel-like consistency and the transparency of the vitreous body due to its ability to bind water. Two thirds of the 65-85 year olds complain about the occurrence of “flying flies”. Even highly short-sighted young people can be affected by these phenomena because their vitreous body is longer.
The “Mouches volant” are usually harmless and do not restrict vision. However, patients’ subjective sense of vision is limited and the symptoms associated with vitreous opacity are perceived as annoying. However, the less attention one pays to the phenomena, the less they are seen.
Therefore, the severity of the disease is mainly determined by the degree of severity, the location of the spots in the central field of vision and the proximity to the retina. In addition, the mobility of the opacities and the subjective impairment are criteria for the disease value. In case of beginning symptoms (initial perception of the spots), an ophthalmologist should be consulted who can exclude pathological causes.
Furthermore, the eyes should be checked annually by an ophthalmologist from the age of forty onwards, so that pathological processes can be detected and stopped early. Special caution and clarification is advised if the clouding symptoms occur in dense swarms or flashes of light, because then a retinal break-off could have occurred and a retinal detachment is imminent. More severe symptoms, which are perceived as “sooty rain”, can be caused by bleeding into the vitreous body, which is triggered by retinal detachment, diabetes mellitus or metabolic diseases.
In general, there is no need to worry about mild symptoms, as they are harmless and merely due to an age-related degeneration process. If the first symptoms appear, a doctor should be consulted to clarify the cause. It can be a harmless vitreous clouding or a more serious disease.
In order to make this differential diagnosis, it is first of all important that the ophthalmologist takes a detailed medical history (questions about the disease history). Questions about the form, first appearance, first perception of the black spots are asked. After the detailed “questioning”, the doctor will examine the eye more closely.
First, the patient will be given eye drops, which will initially weaken the vision for a few hours. The drops dilate the pupils. The doctor shines a so-called slit lamp into the eye.
With his magnifying glass he can thus assess the individual parts of the eye. In the case of vitreous opacity, the doctor can recognize dark shadows.If the examination with the slit lamp is not clear, other examination methods can be used. An ultrasound examination serves to clarify a retinal detachment.
Examinations such as X-rays, computed tomography or magnetic resonance imaging clarify whether a foreign body in the eye causes the symptoms of vitreous opacity. As a rule, no treatment measures are necessary after the diagnosis of vitreous opacity. In order to improve the symptoms of the black spots, the patient can do a few things himself.
Sunglasses with high sun protection prevent the symptoms from being aggravated by high levels of sunlight. For the same reason, self-tinting lenses are recommended for short-sighted patients. The brightness should be reduced during intensive use of electronic devices to make work on them as comfortable as possible.
The eyes can be strengthened by healthy food and plenty of water. In addition, certain vitamins and plant ingredients (Vitrocap), which can be taken as a capsule, help to cover the increased need for micronutrients. Healthy nutrition and daily exercise not only strengthen the entire body, but also help to lose weight.
This is important, as overweight is described in the specialist literature as a factor influencing vitreous clouding. In addition, you should strengthen your eyes by preventing irritated or dry eyes with eye drops. A last option for the therapy of vitreous opacity is the surgical removal of the vitreous, the so-called vitrectomy.
However, this operation should be avoided in any case and should only be carried out in extreme cases. We speak of an extreme case when the patient is in pain and perceives flashes of light. Only in very few cases is there no other option than surgical removal of the vitreous body.
The procedure is usually performed under local anesthesia. The removal of large parts of the vitreous body is done by suction, removing the particles that lead to the image of flying flies. The removed part of the vitreous body is filled with silicone oil, gas or a saline solution to remove the vitreous body.
In general, thanks to precise technology, surgical removal of the vitreous body involves fewer surgical risks, and with minimal access to the operating area, not even sutures are necessary, as the openings close again by themselves. Nevertheless, this procedure does involve some risks: most patients develop a pronounced cataract after one or two years of surgery, which requires further surgery. In this case, a precise risk-benefit analysis must be carried out, especially in young patients.
Another option describes laser treatment, which is less risky than surgical removal of the vitreous body. The vitreous body is irradiated with a laser in several sessions to destroy the lumps contained in the vitreous body. This procedure is called photodisruption.
Laser treatment is a technically difficult procedure that ultimately does not guarantee the complete removal of the interfering particles. Usually performed on an outpatient basis in the practice, the eyes are anaesthetized with eye drops. The patient looks through a contact glass which is connected to the laser, while the doctor adjusts the setting of the laser and determines the irradiation site by looking through a microscope.
The application of the laser lasts between 30 and 60 minutes and then anti-inflammatory eye drops are applied. In most cases, the vitreous clouding is due to an age-related process. However, there are also pathological vitreous opacities, such as asteroid hyalosis, in which the opacities are caused by white deposits and usually only occur in one eye.
In addition, in the clinical picture of asteroid hyalosis, the opacities are not mobile and are firmly associated with the framework of the vitreous body. It is suspected that this form of vitreous opacity is caused by a poorly controlled diabetes mellitus. In rare cases, vitreous opacities also occur after eye injuries or inflammation.
Before any treatment, an extensive anamnesis and examination must be performed. If the black spots appear for the first time, an ophthalmologist must be consulted urgently. He will then determine whether the vitreous clouding is unproblematic or whether it is a different disease. Normally, a vitreous opacity does not require further treatment and the patient’s symptoms subside of their own accord.After several months to years, the flying mosquitoes can become fewer or even disappear completely.
