Which test evaluates tear film stability after fluorescein instillation?

Which test evaluates tear film stability after fluorescein instillation?

• A. TBUT
• B. Schirmer
• C. TearLab
• D. NaFl

Answer: (A)

Tear film stability is assessed by timing how long the tear film remains continuous after a blink when fluorescein is used. In this test, a small amount of fluorescein is instilled, the patient blinks to distribute it, then you measure the interval from the last blink to the first appearance of a dry spot on the cornea under cobalt blue light. The longer this tear break-up time, the more stable the tear film is; a short time indicates instability, often seen in dry eye or evaporative conditions. The other options don’t measure this stability: the Schirmer test gauges tear production, TearLab measures tear osmolarity, and sodium fluorescein is the dye used—not a stand-alone stability test.

Tear film stability is assessed by timing how long the tear film remains continuous after a blink when fluorescein is used. In this test, a small amount of fluorescein is instilled, the patient blinks to distribute it, then you measure the interval from the last blink to the first appearance of a dry spot on the cornea under cobalt blue light. The longer this tear break-up time, the more stable the tear film is; a short time indicates instability, often seen in dry eye or evaporative conditions. The other options don’t measure this stability: the Schirmer test gauges tear production, TearLab measures tear osmolarity, and sodium fluorescein is the dye used—not a stand-alone stability test.