Tårfilmsstabilitet

Tårfilmsstabilitet refers to the ability of the tear film, a thin liquid layer covering the surface of the eye, to remain intact and functional. This stability is crucial for clear vision and the health of the ocular surface. The tear film is composed of three layers: an outer lipid layer, a middle aqueous layer, and an inner mucin layer. Each layer plays a specific role in maintaining tear film integrity. The lipid layer, produced by the meibomian glands, prevents rapid evaporation of the aqueous layer. The aqueous layer, produced by the lacrimal glands, provides moisture and contains essential proteins and antibodies. The mucin layer, produced by goblet cells, promotes the even spreading of the aqueous layer across the hydrophobic corneal surface.

Instability of the tear film can lead to a condition known as dry eye disease. This can manifest as symptoms such as grittiness, burning, stinging, redness, and blurred vision. Factors contributing to tear film instability include aging, hormonal changes, environmental conditions (like dry or windy weather), prolonged screen time, certain medications, and underlying medical conditions such as Sjögren's syndrome or blepharitis.

Assessment of tear film stability often involves clinical tests. The tear breakup time (TBUT) measures how long the tear film remains intact before breaking up, indicated by dry spots on the cornea. Other tests may include Schirmer's test to assess tear production and vital staining to identify areas of ocular surface damage. Maintaining good tear film stability is important for comfortable and healthy vision.