The Healthy Three-Layer Tear Film
A stable tear film protects and optically smooths the cornea.
- ~7 µm: Total film thickness (placeholder figure)
- >10 s: Normal TBUT (placeholder figure)
- ~15/min: Blink rate (placeholder figure)
- 3: Layers (lipid, aqueous, mucin)
Layer architecture
Placeholder: each layer serves a distinct protective role.
Meibomian Gland Dysfunction & Lipid Loss
A thinned lipid layer lets tears evaporate faster than normal.
- ~50%: MGD prevalence (placeholder figure)
- ↑2–4×: Evaporation rate (placeholder figure)
- ↓60%: Lipid thickness (placeholder figure)
- <10 s: TBUT (placeholder figure)
Evaporative dry eye
Placeholder: gland blockage reduces oil secretion onto the tear surface.
Reduced Lacrimal Secretion
Low aqueous volume concentrates tears and irritates the surface.
- Sjögren / non-Sjögren: Aqueous deficiency type (placeholder figure)
- ↑ hyperosmolar: Tear osmolarity (placeholder figure)
- <5 mm: Schirmer test (placeholder figure)
- <5 s: TBUT (placeholder figure)
Hyperosmolar stress
Placeholder: thinning aqueous layer raises osmolarity and damages cells.
Tear Film Breakup and Ocular Surface Dryness
Dry spots expose the cornea, triggering pain and inflammation.
- <3 s: TBUT (placeholder figure)
- High: Surface staining (placeholder figure)
- ↑ elevated: Inflammatory markers (placeholder figure)
- Severe: Symptom score (placeholder figure)
Vicious cycle
Placeholder: instability and inflammation reinforce each other.
Stabilization with Artificial Tears or Cyclosporine
Lubricant drops or cyclosporine restore film stability over time.
- Fast, short-term: Artificial tears effect (placeholder figure)
- Slow, disease-modifying: Cyclosporine effect (placeholder figure)
- ~weeks: Onset (cyclosporine) (placeholder figure)
- ↑ toward normal: TBUT recovery (placeholder figure)
Restoring the film
Placeholder: treatment rebuilds layer thickness and reduces inflammation.