The Break-Up-Time (Break-Up-Time) test is performed in the diagnosis of dry eye syndrome and other disorders of ocular surface lubrication. It is a valuable, non-invasive diagnostic method in which the parameter under study is the stability of the pre-corneal tear film.
The assessment is made by measuring the time elapsed between blinking and the break in the tear film. The test reveals abnormalities in the lipid and/or mucosal layer and indirectly with a normal lipid layer and allows assessment of the aqueous layer, the thinning of which leads to reduced BUT time.
The test assesses the thickness and quality of the tear film’s lipid layer, responsible for maintaining its surface tension and stability. The test can be performed using two methods:
No other diagnostic tests should be performed immediately before the fluorescein test.
The doctor injects fluorescein (0.15% drops or fluorescein strip) into the patient’s conjunctival sac, then the patient sits down at the slit lamp. After blinking several times, he opens his eyes (do not open them too wide), looks straight ahead and refrains from blinking for a while. When they are opened, the time from the last blink until the tear film breaks is measured. In the cobalt blue light of the lamp, the moment is visible as black lines or spots on a green-yellow background of glowing fluorescein. The measurement is usually taken three times and the average is calculated.
NOTE: administration of fluorescein significantly alters the pre-ocular tear film; too much fluorescein overestimates the results, causing them to be false negatives. One should carefully interpret the results when one observes a tear film interruption in the same place; it can be induced by keratoepitheliopathy such as corneal scarring.
Results and interpretation of the classic tear film break time study:
After the test, redness of the eyes and a transient foreign body sensation in the eye are possible.
