Function of the meibomian glands

The meibomian glands produce the lipid portion of the tear film. The thin, oily film forms the lipid layer, lays itself protectively over the aqueous phase of the tear fluid and forms the top layer of the tear film.

This outer layer functions like a protective shield that stabilises the tear film and keeps small foreign bodies and germs from getting in. At the same time, the lipid layer ensures that the aqueous layer of the tear film does not evaporate prematurely, which would cause it to rupture and leaving the eye surface unprotected.

If the meibomian glands function normally, the lipid layer supports the natural protective mechanism of the eye surface through the tear film. However, if sebum production is disturbed, the aqueous part of the tear fluid can evaporate before the next blink, which can lead to dry, irritated and itchy eyes. A common glandular dysfunction is the meibomian gland dysfunction, a chronic disease of the sebaceous glands located in the eyelid margin in which the excretory ducts become blocked or the quality or quantity of lipid secreted is insufficient.

Blocked meibomian glands are often the reason for dry eyes. There are various causes of these small glands becoming blocked:

• Acute inflammation: In the case of a bacterial infection, pathogens enter the gland ducts and can trigger an inflammation there. A bacterial infection of a single meibomian gland causes a usually painful stye (hordeolum) to form at the eyelid margin. It often heals on its own after a few days, but in some cases it requires medical treatment.
• Chronic inflammation: Chronic inflammation of the eyelid margins (blepharitis) also leads to the accumulation of secretions in the sebaceous glands. The persistent inflammation irritates the lid margins, which impairs the production of secretion. If a blockage occurs in only one gland, the secretion may accumulate there and a chalazion may develop. With heat and careful eyelid margin hygiene, the build-up of secretions can be resolved.
• Meibomian gland dysfunction: Meibomian gland dysfunction (MGD) is a chronic dysfunction of secretion production in the meibomian glands. In this case, too little or too much sebum is produced, and the composition can also become unbalanced. The result is congestion of secretions in the gland ducts, swollen eyelids and deposits on the eyelid margins between the eyelashes. MGD can lead to chronic eyelid margin inflammation, which should be treated by consistent eyelid margin hygiene with heat treatment.

Blocked meibomian glands can lead to eye symptoms due to the accumulation of secretions in the gland ducts, e.g.

• swollen eyelids
• red eyelid margins
• sticky eyelids, especially in the morning
• encrustations
• itchy lid margins
• dry eyes
• watery eyes
• foreign body sensation
• impaired vision
• sensitivity to light

An ophthalmologist detects blocked meibomian glands during an examination. If the symptoms mentioned occur, they should always be investigated by a doctor, because blocked meibomian glands are often caused by a meibomian gland dysfunction that should be treated.

For an intact tear film, you can support the meibomian glands with regular eyelid margin hygiene and heat treatment. For one thing, this removes sebum residues from the eyelid margins, keeps the gland openings clean and prevents inflammation. In addition, the heat stimulates the blood flow to the eyelids and this promotes glandular function.

Daily cleaning and care of the eyelid margins is the only effective treatment option for people with chronic eyelid margin inflammation (blepharitis) or meibomian gland dysfunction (MGD). However, it is also advisable as a preventive measure for healthy eyes. This is because eyes are sensitive, and can be severely strained in modern everyday life by screen work and environmental influences and can use every form of support against the eye surface drying out.