Understanding your tear makeup
The tear film is made up of three layers: the mucin (mucous) layer, the watery aqueous layer and the oily lipid layer. The lacrimal gland under the eyebrow produces tears which form the aqueous layer. The Meibomian Glands in the upper and lower eyelids secrete oil to make up the lipid layer.
There are two types of Dry Eye:
1. Evaporative Dry Eye is the cause of the majority of Dry Eye cases. This is when tears are produced at normal quantities but evaporate too quickly.There are two main causes of evaporative dry eye: Meibomian Gland dysfunction and environmental factors.
- Meibomian Gland Dysfunction (MGD) is when the oil-producing Meibomian Glands are not working properly. This diminishes the lipid layer of the tear film, causing aqueous tears to evaporate quickly.
- Environmental factors such as air conditioning, extended screen time or wind can result in excessive tear evaporation, leading to dryness and irritation.
2. Aqueous Deficient Dry Eye is caused by low production of aqueous tears. This is far less common than Evaporative Dry Eye, and is commonly due to auto-immune disease, medication or eye surgery.
You may find yourself using eye drops regularly to try to lubricate your eyes.