If the vitreous body of the eye changes, it can lead to small, moving areas of cloudiness that seem to fly around in front of the eye – just as if a fly or mosquito were constantly in front of the eye.
These minimal areas of vitreous opacity are usually completely harmless (but can occasionally be annoying). However, they can also be an indication of a significant change in the vitreous body, which should not be overlooked.
The human eye is shaped like a hollow sphere. Facing the outside, the wall of the eye has a clear window – the cornea – which is protected by the eyelids. The sphere is spanned by the iris, which divides the eye into a small anterior (front) chamber and a posterior chamber, which is approximately five times larger. In the centre of the iris is an opening called the pupil. The area in front of the iris is called the anterior chamber of the eye; the area behind the iris is called the vitreous chamber. This vitreous chamber is filled with a colourless, transparent, gelatinous mass, the vitreous humour (or the medical term corpus vitreum). The vitreous chamber is completely lined by the retina.
Changes in the structure of the vitreous body occur physiologically (physiology = the normal processes and functions of the human organism) as the body ages, which is why regular check-ups by a specialist are recommended from the age of 40.
The vitreous humour usually liquefies from the age of 20 onwards. This phenomenon is perceived by most people as ‘floaters’ (= mouches volantes) and represents a harmless finding that does not require treatment.
If, on the other hand, a person perceives lightning flashes or the ‘mouches volantes’ suddenly appear in thick ‘swarms’, the retina should be examined to rule out retinal detachment. Injuries and diabetes can also lead to dangerous bleeding. This must be checked closely and, if necessary, removed with surgical intervention.
If the vitreous humour is clouded, e.g. due to blood or inflammation material, contains foreign bodies that have penetrated the eye from the outside, or pulls at the retina with scarred thickening and even detaching it from its base, the vitreous humour must be removed by means of an appropriate surgical procedure and replaced with a special fluid.
Vitreous diseases can seriously impair vision, as all rays of light must pass through the vitreous to reach the retina.
Changes to the vitreous humour can manifest themselves through a variety of symptoms:
In most cases, the symptoms described do not indicate anything bad. However, in order to have certainty in excluding damage to the retina or have it treated quickly, a person perceiving lightning flashes and recurrent cloudiness of the eye should consult an ophthalmologist on the same day to have their symptoms assessed.
Important to know: Pathological changes to the vitreous body are usually closely related to a retinal disease.
The vitreous humour consists of 98% water, 2% hyaluronic acid, to which the water is bound, and a collagen structure that ensures the stability of the vitreous humour. Ageing processes lead to deposits in the vitreous humour and the collagen fibres clump together, which means that the vitreous humour shrinks as a whole. In addition, water-filled crevices and lacunas (= cavity, depression) form – known by the medical term liquefaction of the vitreous humour – and the particles floating in it are perceived as moving shadows, threads or lint (= ‘mouches volantes’).
In addition to this age-related shrinkage of the vitreous humour, there are other reasons for a change in the vitreous humour:
Bacteria, viruses and fungi can cause vitreous inflammation: These may have entered the vitreous humour as a result of either trauma, external influences or a surgical procedure.
As the vitreous humour is located in front of the retina, changes can usually be identified using the ophthalmoscope (this instrument is used to inspect the visible parts of the eye, especially the retina and the blood vessels supplying it).
Depending on the symptoms, visual acuity, the field of vision or medical history (professional questioning about potentially medically relevant information) can provide information on the genesis (= origin, development) of the disease.
For diagnostic purposes, the ophthalmologist also examines the vitreous humour with the slit lamp and the Goldmann lens (a special ophthalmological examination instrument that looks like a funnel-shaped magnifying glass); he she also uses eye drops to dilate the pupil, which makes it far easier to examine the back of the eye and so assess the retina.
If, for example, the lens is clouded due to cataract disease, a direct examination of the interior of the eye may not be possible without restriction. In this case, the ophthalmologist may choose to use an ultrasound examination to produce an image of the tissue in the eye.
In addition, vitreous detachment is especially easy to detect using optical coherence tomography, which uses light pulses instead of ultrasound waves to create a two-dimensional image of the tissue layers in the eye. This procedure provides more accurate images than the ultrasound examination of the eye.
If the vitreous humour is bleeding, the eyeball is also examined using an ophthalmoscope and Goldmann lens to determine the source of the bleeding. In the case of a very severe bleeding, vision is impaired and further investigations are required to determine the cause (e.g. an ultrasound examination, a CT (computed tomography) or an angiography (vascular examination) of the eye’s blood vessels).
In medicine, there are five different types of vitreous changes:
Disease-related or age-related changes to the vitreous humour can have serious consequences and lead to impaired vision. Either drug-based or surgical treatment is carried out depending on the disease.
The various changes to the vitreous humour are treated as follows:
‘Mouches volantes’ can be dissolved using a laser. However, the treatment is only suitable for opacities that are located at a safe distance from the retina.
In the case of severe vitreous opacity caused by many areas of ‘mouches volantes’, bleeding or major clumping on the vitreous membrane, removal of the vitreous humour is an option, in principle. However, this operation poses a number of risks, such as clouding of the eye lens, infections and/or retinal problems. In the case of vitrectomy (see also point 1) for retinal detachment, the risk associated with treatment is clearly lower than the risk posed by the problem being treated, but this is not normally the case with vitreous opacity.
If you have undergone a vitrectomy, you should not exercise, swim or fly for up to three weeks, but rather take care of yourself to the best of your ability. It is also essential to avoid rubbing the eye or pressing hard on the eye. Your eye will not heal completely until after about four weeks.
It is also advisable to consult an ophthalmologist regularly and have your eyes checked, also if you notice any a vitreous changes, as this is the only way to detect and treat any further changes and, above all, deterioration.
The tissue is deemed to heal completely after four to six weeks on average. However, it may take months for vision to reach the best possible level.
Complete vitreous detachment usually takes a few days to weeks. Rarely, the vitreous humour remain stuck to individual parts of the retina for months or years, causing ‘lightning flashes’ from time to time.