What is the lipid layer thickness in healthy dogs vs dogs with EDED?

• A. 30-80 nm in healthy; 15-30 nm in EDED
• B. 15-30 nm; 30-80 nm
• C. 25-50 nm; 10-25 nm
• D. 40-90 nm; 20-60 nm

Answer: (A)

Tear film stability largely depends on the lipid layer produced by the meibomian glands. This outermost layer acts as an evaporation barrier, so a robust lipid layer shows up as thicker measurements in nanometers and helps keep the tear film intact. In healthy dogs, the lipid layer is thicker, typically in the tens of nanometers range (around 30–80 nm), reflecting adequate lipid production and a stable tear film. In dogs with EDED, the lipid layer is thinner because meibomian gland function or lipid quality is impaired, leading to increased evaporation and tear film instability; this is reflected by a thinner lipid layer, roughly 15–30 nm. So the pattern of thicker lipid layer in health and thinner layer in EDED fits the expected pathophysiology, whereas the reverse or mismatched magnitudes would not align with how evaporative dry eye disease alters tear film lipids.