Dry eyes? It's not just a lack of water
Meet the three parts of your tear film, and the three types of dry eye.
- 01Dry eyes? It's not just a lack of water
- 02Meibomian glands: your eyes' oil factories
- 03Why won't my tears stay put?
- 04Why does dry eye keep coming back?
- 05Health conditions that can dry your eyes
- 06Everyday habits that quietly feed dry eye
- 07“It's just dry eyes”? It's not that simple
- 08Managing dry eye: from home to clinic
- 09In-clinic treatment: IPL, RF & expression
The tear film: thin, but precisely built
Part 01 · 01Outer · lipid (oil) layer
Like cling wrap, it slows evaporation.
Middle · aqueous (water) layer
Moistens and cleans, and carries oxygen and nutrients.
Inner · mucin layer
Helps tears spread and stick to the eye's surface.
The whole tear film is only about 3 microns thick. Current research sees the water and mucin as one mixed gel, topped by oil.
Three layers, three ‘factories’
Part 01 · 02Meibomian glands → oil
Inside the upper and lower lids, opening behind the lashes.
Lacrimal gland → water
In the upper outer part of the eye socket.
Goblet cells → mucin
In the conjunctiva over the white of the eye and inner lids.
Each blink mixes and spreads all three. Excess tears drain through the puncta into the nose.
The three types of dry eye
Part 01 · 03Think of it layer by layer. The problem can start in any of them.
Evaporative · an ‘oil’ problem
The meibomian glands make too little oil, or poor-quality oil, so tears evaporate too fast. This is the most common type.
Aqueous-deficient · a ‘water’ problem
The lacrimal gland makes fewer tears, for example with age, Sjögren's syndrome or some medicines.
Mucin / surface · a ‘stick’ problem
Surface inflammation damages goblet cells and surface mucins, so tears won't stay put.
The latest international consensus (TFOS DEWS III, 2025) moves away from a simple two-type split. Instead it looks for each person's main drivers: oil, water, mucin, eyelid or surface problems.
The three types often occur together
Part 01 · 04of people with dry eye show signs of meibomian gland dysfunction (MGD)
Source: Lemp MA, et al. Cornea 2012 (US dry eye patient sample)Oil problems are the most common
Evaporative dry eye is the majority, and a key reason symptoms keep coming back.
Most people have a ‘mixed’ type
One problem triggers another, and mixed cases tend to be more severe.
Identify the type first
The same dryness can have different causes, and need a different focus.
Key takeaways
Part 01- 01Your tear film has oil, water and mucin, each from its own source
- 02Dry eye can start in any layer; oil problems are the most common
- 03Most people are ‘mixed’: identify the type, then treat
Book an eye surface assessment.
Eyes that often feel dry or gritty, or vision that comes and goes? Find out which type you have and what’s driving it.
General health information only, not personal advice. Everyone’s eyes are different. An optometrist or doctor should examine you before any treatment is decided.