Which sign is most consistent with dry eye by measuring tear film stability?

Which sign is most consistent with dry eye by measuring tear film stability?

• A. TBUT less than 10 seconds
• B. Normal TBUT
• C. TBUT greater than 15 seconds
• D. TBUT unaffected

Answer: (A)

Tear film stability is assessed by tear breakup time (TBUT). In dry eye, the tear film destabilizes quickly after a blink, so the first break appears early. A TBUT under 10 seconds shows this rapid breakup and matches the typical pattern of dry eye, making it the most consistent sign when measuring tear film stability. Normal TBUT is about 10–15 seconds or longer, indicating a relatively stable tear film and not dry eye. TBUT longer than 15 seconds or unchanged TBUT would not fit the dry-eye pattern.

Tear film stability is assessed by tear breakup time (TBUT). In dry eye, the tear film destabilizes quickly after a blink, so the first break appears early. A TBUT under 10 seconds shows this rapid breakup and matches the typical pattern of dry eye, making it the most consistent sign when measuring tear film stability. Normal TBUT is about 10–15 seconds or longer, indicating a relatively stable tear film and not dry eye. TBUT longer than 15 seconds or unchanged TBUT would not fit the dry-eye pattern.