Vitreous opacity: causes, symptoms and treatment (Flying Mosquitoes)

Suddenly shadows, dots or threads float through your field of vision – but no, it’s not real gnats that are annoying you, it’s mouches volantes! These vitreous opacities are usually harmless, but can be quite annoying, especially when looking at bright surfaces. But what is actually behind them? And when is treatment necessary? In this article, you will find out why the vitreous body changes over time, which therapies really help and when surgery is an option.

What is vitreous opacity?

Vitreous opacification occurs when the normally clear fluid inside the eye changes. The vitreous consists of a liquid gel-like substance that is 98% water and 2% collagen fibers and hyaluronic acid. With increasing age or as a result of another disease, the collagen fibers can clump together, causing so-called mouches volantes (“flying gnats”) to appear in the field of vision.

These opacities in the vitreous body are particularly visible when looking at bright surfaces such as a sheet of paper or the sky. Although they are harmless in most cases, they can impair the quality of vision enormously.

Difference to vitreous detachment and retinal detachment

Vitreous opacity vs. vitreous detachment

• Vitreous opacities are caused by the clumping of collagen fibers within the vitreous body, which are perceived as opacities in the eye.
• A vitreous detachment occurs when the vitreous detaches from the retina. This is a normal ageing process, but can also lead to flashes and shadows in the field of vision.

Vitreous opacity vs. retinal detachment

• While a vitreous opacity often does not require treatment for the time being, a detached retina can lead to blindness and requires immediate treatment.
• Warning signs of retinal detachment:
  • Sudden increase in mouches volantes
  • Flashes in the field of vision
  • Black shadow that spreads across the field of vision

Important: If new, severe symptoms occur or the opacities in the vitreous suddenly worsen, an ophthalmologist should be consulted as soon as possible to rule out a serious eye disease.

Causes of vitreous opacity: why do floaters occur?

Vitreous opacity is often a normal aging process, but can also be caused by other factors.

Common causes of vitreous opacities:

• Natural liquefaction of the vitreous body: With increasing age, the vitreous body loses its homogeneous structure – the fibers clump together and clouding occurs in the eye.
• Detachment of the vitreous body: The vitreous body can detach from the retina over the years, which is why so-called mouches volantes occur particularly frequently.
• Bleeding inside the eye: Injuries or vascular changes can cause blood particles to be deposited in the vitreous body.
• Consequence of another disease: inflammation, severe short-sightedness, diabetes or cataract surgery can promote the occurrence of opacities in the vitreous body.

Symptoms: How does vitreous opacity manifest itself?

Vitreous opacity is mainly manifested by visible disturbances in the field of vision, which are perceived to varying degrees depending on the lighting conditions and movement of the eyes.

Typical symptoms of vitreous opacity:

• Haze or shadows in the field of vision, especially when looking at bright surfaces (e.g. a sheet of paper or the sky).
• Blurred or distorted vision that cannot be corrected by glasses.
• Blurred structures that move with the eye movements and then slowly sink downwards.
• Sudden perception of new opacities, often in connection with a feeling as if something is in the eye.

What do flying mosquitoes / mouches volantes have to do with it?

Mouches volantes (French for “flying gnats”) are probably the best-known side effect of vitreous opacity. These are small, transparent or dark dots, threads or spots that appear to move in the field of vision.

Why do mouches volantes occur?

• The vitreous body consists of a liquid gel-like substance that changes and liquefies over time.
• Collagen fibers clump together and form opacities in the vitreous body, which are perceived as “flying gnats”.
• When looking at bright surfaces (e.g. a sheet of paper or the sky), the haze becomes particularly visible.
• As the clouding floats in the eye, it appears to “fly” with every eye movement.

Are mouches volantes dangerous?

• In many cases, they are a normal aging process and do not require treatment.
• If the mouches volantes suddenly increase, accompanied by flashes of light or shadows in the visual field, this could indicate a vitreous detachment or a retinal detachment – in this case an immediate visit to the doctor is necessary.

If you find the flying mosquitoes particularly annoying, you can have them removed using special treatment methods.

Vitreous opacity treatment: What really helps?

If treatment of vitreous opacification is necessary at all, then there are various options:

When treatment is necessary – and when it is not

In most cases, vitreous opacities and mouches volantes are bothersome but harmless. Treatment is not always necessary, as the brain often gets used to the opacities in the vitreous body and they become less noticeable over time.

When is no treatment necessary?

• If the quality of vision is not significantly impaired.
• If the flying midges are only visible occasionally or in certain light situations.
• When the brain gets used to the clouding and fades it out over time.

When should treatment be considered?

• If the mouches volantes severely impair vision, e.g. when reading or driving.
• If the clouding in the eye suddenly increases or enlarges.
• If there are also flashes of light, shadows or black dots in the field of vision – this could be an indication of vitreous detachment or retinal detachment.
• If the strain in everyday life becomes too great and the quality of vision suffers enormously.

In many cases , vitreous opacities that do not require treatment can be made less disturbing by simple means – for example, by avoiding looking at bright surfaces or using self-tinting lenses.

Treatment with the laser for vitreous opacities

Laser treatment (laser vitreolysis) may be an option for patients who suffer from severely disturbing mouches volantes. This involves using a special laser to break up the opacities in the vitreous body so that they are less noticeable or dissolve completely.

How does laser vitreolysis work?

• A YAG laser is used to break up the clumped collagen fibers in a targeted manner.
• The turbidity is broken down into smaller particles, which are then better distributed in the vitreous body.
• The treatment is performed on an outpatient basis and usually only takes a few minutes per eye.
• In some cases, several sessions are required to achieve the best quality of vision.

Advantages of laser treatment:

• Non-invasive: No surgical intervention required.
• Quick implementation: The session only takes about 20-30 minutes.
• Better vision: Many patients report a significant improvement in the quality of their vision.

Possible risks:

• The success of the treatment depends heavily on the position and density of the opacities.
• In rare cases, temporary sensitivity to glare or slight inflammation may occur.
• Not all patients are suitable for laser treatment – an individual examination is necessary.

Laser vitreolysis is particularly useful for patients whose vitreous opacities severely impair their quality of life, but who have no retinal detachment or other eye diseases.

Vitreous opacification surgery: vitrectomy as the last option

If vitreous opacities (mouches volantes) impair the quality of vision enormously and neither the body adapts to them nor laser treatment is successful, a vitrectomy can be considered. However, this surgical treatment is associated with higher risks and is therefore only recommended in severe cases.

What is a vitrectomy?

Vitrectomy is a surgical procedure in which the vitreous body is removed and replaced with a clear liquid. In the process:

• The ophthalmologist removes the cloudy vitreous body through tiny incisions.
• The eye is stabilized with a special saline solution or gas filling.
• The body replaces the fluid by itself after a while.

Is the vitrectomy painless?

Yes, the operation is performed under local anesthesia or, if desired, under general anesthesia. Patients do not feel any pain during the procedure. After the operation, there may be a slight feeling of pressure or irritation, but this can be treated with eye drops.

When is a vitrectomy advisable?

• If the opacities in the vitreous body severely impair vision.
• If severe mouches volantes do not subside even after months or years.
• If the laser treatment does not bring any improvement.

Risks of the operation:

• Retinal tears or detachment are rare but possible.
• Increased risk of cataracts – cataract surgery often has to be performed later.
• Infections or postoperative bleeding (rare, but to be taken seriously).

As vitrectomy is an invasive operation, it is only performed in severe cases. Patients should therefore seek detailed advice from an ophthalmologist as to whether this treatment is really necessary.