Tear Film Break-Up Time

Tear Film Break-Up Time (TBUT) is a crucial diagnostic test in ophthalmology that assesses the stability of the tear film covering the surface of the eye. It measures the time taken for the tear film to break up after a blink, indicating how well tears are maintaining the ocular surface. A healthy tear film is essential for clear vision and comfort, as it provides moisture, lubrication, and protects against infections.

During the TBUT test, a fluorescein dye is often used to enhance visibility. The patient blinks several times before a clinician observes the eye through a slit lamp microscope equipped with a cobalt blue filter. The appearance of dry spots or irregularities on the cornea after blinking helps determine the TBUT. Normal TBUT values typically range between 10 to 15 seconds. A shorter TBUT may indicate dry eye syndrome, meibomian gland dysfunction, or other ocular surface disorders, prompting further evaluation and treatment to improve tear film stability and patient comfort.