The tear film
The tear film
The tear film helps keep the cornea and conjunctiva healthy by supplying nutrients, flushing away waste products and acting as a protective barrier. It is made up of three layers.11
Click on the hotspots on the diagram to find out more about the different layers of the tear film.
Types of dry eye
There are two types of dry eye that can occur when the tear film is disrupted:12
- Aqueous deficient dry eye is a less common type of dry eye and occurs when the lacrimal glands don't produce enough fluid and proteins to maintain tear film hydration.8
- Evaporative dry eye is caused by deficiency or disruption of the tear film's lipid layer which leads to excess tear evaporation and dryness. This is most often caused by Meibomian gland dysfunction.11 This is the most common type, accounting for 80% of dry eye patients.8
Check your understanding
Click and drag the correct percentage below into the box beneath.
20%
40%
60%
80%
 of dry eye patients have evaporative dry eye.
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Correct! Click next to find out more about how evaporative dry eye can be best treated.