Which of the following signs is least associated with evaporative dry eye?

• A. TBUT < 10 seconds
• B. 3 and 9 o'clock lissamine green staining
• C. MGD
• D. Tear meniscus < 0.2 mm

Answer: (D)

Evaporative dry eye is driven by Meibomian Gland Dysfunction that reduces the lipid layer of the tear film, leading to increased evaporation and instability of the tear film. This instability shows up as a shortened tear breakup time, since the tear film breaks up faster without a stable lipid layer. Meibomian gland disease also produces lid-margin changes and staining patterns at the 3 and 9 o’clock positions, reflecting surface exposure and gland dysfunction. MGD is a primary driver of evaporative dry eye, so signs of lipid-layer deficiency and lid-margin disease are strongly associated. In contrast, a low tear meniscus height indicates reduced tear volume, i.e., aqueous-deficient dry eye, not primarily evaporative. Therefore a tear meniscus less than 0.2 mm is least associated with evaporative dry eye.