Three Layers of the Tear Film (older definition)
Bridgitte Shen Lee, OD, FAAO, FBCLA, FEAOO
Practice Co-Owner @Vision Optique | Director for Clinical Research @Ocular Aesthetics | Owner @iTravelCE
Link to learn more about Dry Eye Disease
The human tear film is composed of 3 layers:
- Mucin: innermost layer, produced by the Goblet Cells
2. Aqueous: bulk of the tear, produced by the Lacrimal Gland.
3. Lipid: outer surface layer, produced by the Meibomian Glands (inside the lids)
Each layer has a distinct function in maintaining good tear quality and ocular surface homeostasis, and preventing tear evaporation. When one layer becomes deficient, the symptoms of dry eye disease appear.
Depending on which layer of the tear film is deficient, treatment methods will vary. Sometimes there is more than one layer affected. Your eye care professional will be able to evaluate your eye and determine what type of dry eye you may have as well as how to treat and manage it.
The two types of Dry Eyes are Aqueous Deficiency Dry Eye (aqueous or tear layer is affected) and Evaporative Dry Eye (lipid layer is affected). Evaporative Dry Eye is more common than Aqueous Deficient Dry Eye, however many patients present with both types of Dry Eyes.
Meibomian Gland Dysfunction (MGD) is the leading cause of the Evaporative Dry Eye Disease.