(posted apr 2003)

TBUT means "tear break-up time".

The point of this test is to determine how quickly your tears evaporate ("break up"). The doctor places sodium fluorescein dye on the eye, temporarily "staining" it. He then watches through the slit lamp to see how long it takes for tears to evaporate and dry spots to appear. It should take at least 10-15 seconds. If it takes less, then your lipid layer is probably inadequate. This would suggest that meibomian gland therapy (lid therapy) may help by stimulating the meibomian glands.