September 17, 2011
Tear film breakup time (TFBUT) test
The TFBUT is the time between a complete blink and appearance of the first random corneal dry spot, and indicates relative tear film stability.
It should be performed before any drops are instilled.
Saline-wetted fluorescein strip is touched to the lower tear meniscus to enhance visibility of dry spots. A shortened TFBUT of 1 to 2 seconds suggests mucin deficiency or other ocular surface abnormalities.
Normal TFBUT is 10 to 15 seconds.
There is a test for this called meibography. It's actually pretty simple to perform, but the majority of doctors are probably not well aware of it or experienced with it. I first learned about it from a research optometrist in SoCal, Dr. Paugh. [Source]