Drops, eyelid care, silicone plugs: What treatments are available for dry eyes

It happens every four to six seconds: you blink and tear fluid spreads across the surface of your cornea. As simple as this sounds, the structure of these tears is complex. They consist of three layers - oils, water and mucus - with different functions and are not produced in the same place.

On the outside is the lipid layer, formed by the meibomian glands in the eyelids. The fatty components prevent the evaporation of water in the middle layer underneath - and ensure that the tear fluid is well distributed over the eye.

The middle, aqueous layer is secreted by the lacrimal gland and contains proteins as well as water. These in turn act as part of the non-specific immune system to keep pathogens away from the eye. And the inner layer consists of mucins, i.e. mucus. Special cells in the surface of the cornea produce it. Mucins ensure that the tear fluid adheres to the cornea - because its surface is water-repellent. Thanks to them, everything flows smoothly when blinking: The lipids act as a protective lubricating film between the eye and lens, and they also level out any unevenness in the corneal surface.

However, it can happen that the goblet cells that produce the mucins become permanently irritated and produce too little mucus. Anyone who has worn contact lenses for years may be familiar with this: The foreign body irritates the eye in the long term and every blink hurts. This causes localised inflammation of the cornea, which in turn disrupts the production of the tear film. As a result, the eye is not cleaned and cared for enough and the inflammatory activity increases - a vicious circle.

You can also develop dry eyes without contact lenses. The symptom is actually quite common worldwide: according to this study, dry eye syndrome (DES) affects 5 to 50 per cent of the world's population, depending on the region. Women suffer from it more frequently than men and the prevalence increases significantly with age. What researchers now know: Dry eyes are often a side effect of an autoimmune disease, such as Sjögren's syndrome or rheumatoid arthritis.

Symptoms: How to recognise that you have dry eye

The classic symptom of sand in the eye does not necessarily appear immediately. Paradoxically, dry eye disease often begins with tearing, i.e. with increased production of tear fluid as a protective reaction of the eye. Basically, however, DES "can cause a wide range of eye symptoms, including redness, dryness, discomfort, itching, stinging, burning, irritation, pain, photophobia and foreign body sensation. This is typically accompanied by fluctuating vision with blurred or double vision," according to this study.

Experts distinguish between two forms: In evaporative dry eye, the production of the outermost lipid layer is disrupted and allows too much of the tear film to evaporate. In the hypovolaemic form, on the other hand, too little tear fluid is produced due to a disruption in the aqueous phase of the tear film.However, according to studies, this lack of tears occurs less frequently than the evaporative disorder, according to the German Medical Journal.

Causes: What causes dry eyes syndrome?

There are a number of possible causes. As mentioned, these include mechanical friction caused by (years of) contact lens wear, which can affect the goblet cells. Diseases such as diabetes, Sjögren's syndrome, rheumatoid arthritis and collagenosis also have an impact on the lacrimal glands, as do chemotherapy and medications such as antihistamines, certain blood pressure medications and antidepressants.

Plus: Tear production often decreases during the ageing process and can lead to dry eyes. Last but not least, hormonal status plays a role, especially in women. Pregnancy, menopause and the use of oral contraceptives can change the composition of tear fluid in women.

External environmental factors are also considered to be a cause: tear fluid can evaporate more quickly in low humidity. When working intensively at a computer screen, people tend to blink less frequently (known as "office eye syndrome", which in turn causes the tear film to evaporate more quickly. Environmental pollution and smoke can also irritate the eyes and worsen the symptoms.

Dry eyes: these treatment options are available

If you notice the symptoms described above, it is advisable to visit an ophthalmologist. Also to rule out other eye diseases. At the practice, your tear film will be measured using various tests and instruments (e.g. slit lamp and filter paper strips). If possible, you should avoid irritating factors such as cigarette smoke and excessively dry air in air-conditioned or heavily heated rooms - in the latter case, be sure to air the room several times a day for several minutes. A humidifier can also be helpful.

Tear substitutes

In practice, tear substitutes have proven to be a "basic therapy for all degrees of dry eye", according to the medical journal. Doctors can identify the specific point in your eye where there is a problem with tear film production in order to recommend the right gel or ointment preparations.

Important: Make sure you use products without the preservative benzalkonium chloride, which has been criticised for some time. This guideline from the EU states: "Benzalkonium chloride can also cause irritation to the eye, especially if you have dry eyes or corneal disease (transparent layer at the front of the eye). (...) Benzalkonium chloride should be used with caution in patients with dry eyes and in patients with damaged corneas." Many eye drops do not contain any preservatives at all; seek advice on this.

Eyelid edge care, medication, punctum plugs

Depending on whether DES presents with mild, moderate or severe clinical symptoms, treatment may include artificial tears, eyelid margin care (where bacteria may colonise or the meibomian glands may be blocked) or anti-inflammatory medication. In severe cases of hypovolaemic eye, so-called "punctum plugs" are used: This involves closing off the draining tear ducts with small plugs made of either collagen or silicone.

Omega-3 fatty acids

If necessary, your doctor may recommend oral medication: omega-3 fatty acids, taken with food or as a dietary supplement, are said to have an anti-inflammatory effect according to this study. There are also eye drops with omega-3 fatty acids, but their effectiveness has not been sufficiently clinically evaluated.

However, the consumer advice centre from Germany writes on the current study situation that the effect of orally ingested omega-3 fatty acids on dry eyes has not been proven: "Even at very high doses (3 g/day), omega-3 fatty acids are more likely to achieve a placebo effect. They also have no preventative effect against chronic drying of the conjunctiva and cornea (keratoconjunctivitis sicca). However, there is no reason why you should not consume more omega-3 fatty acids with your normal diet."