How well does non-invasive tear break-up time reflect patient-reported ocular discomfort? Insights from a clinical...

To assess the correlation between non-invasive tear break-up time (NIBUT) and patient-reported symptoms in Dry Eye Disease (DED), and to explore whether NIBUT can serve as a supportive clinical parameter reflecting symptom severity.

This single-centre retrospective study included data from 295 subjects (209 females and 86 males), complaining of chronic ocular discomfort and evaluated in a third-level specialized lab - Laboratory for Cornea and Ocular Surface Analysis, in the period between July 2023 and June 2024. NIBUT was measured with the CA-800 topographer (Topcon Healthcare, Tokyo, Japan), while subjective symptoms were estimated with the Ocular Surface Disease Index (OSDI), the Visual Analogue Score (VAS), and the Numerical Rate Score (NRS).

NIBUT did not correlate significantly with the subjective scores in the total population, including OSDI (r = -0.11, p = 0.43) and VAS (r = -0.06 and p = 0.56) correspondingly. Also, at the level of individual eyes, no significant relationship was demonstrated between NIBUT and NRS scores: for the right eye, r = -0.09, for the left eye r = -0.05; p = 0.12 and 0.39 respectively Only severe OSDI scores showed an inverse correlation with NIBUT values (r = -0.22; p = 0.005).

Although NIBUT offers a standardized and non-invasive assessment of tear film stability, our data suggest that its correlation with patient-reported symptoms is limited and becomes clinically relevant only in subjects with severe OSDI scores. These findings suggest that NIBUT cannot independently diagnose DED, but may be useful as a complementary tool within a multimodal diagnostic approach to DED.