Dr Moïse Tourabaly · Ocular surface

Dry eye: the tear film

A · The three layers of the tear film

Magnified cross-section of the tear film and its three layers. Magnified cross-section above the cornea. From top to bottom: the lipid layer at the surface, the aqueous layer, the mucin layer, then the cornea. The lipid layer limits evaporation. lipid layer aqueous layer mucin layer cornea

B · Stable or unstable film

Surface of the cornea with a stable or unstable film, and the Meibomian glands. The surface of the cornea is covered by a film. The Meibomian glands, at the eyelid margin, produce the oily layer. When the film is stable, it stays continuous. When it is unstable, it evaporates quickly and dry areas appear on the surface. Meibomian glands continuous, even film rapid evaporation, dry areas

Stable film: the three layers stay even between two blinks, the surface is protected and comfort preserved.

Unstable film: the film evaporates too quickly, often through a lack of oily layer. Areas of the cornea become exposed.

Possible symptoms: stinging, a gritty sensation, fluctuating vision, reflex watering.

Diagram for educational purposes. It does not replace an ophthalmological examination. Results vary from one patient to another.