Layers of the tear film
The human tear film is composed of 3 layers: mucin, aqueous, and lipid. Each layer has a distinct function in maintaining good tear quality and preventing tear evaporation. When one layer becomes deficient, the symptoms of dry eye 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.