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

Objective: 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.

Methods: 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).

Results: 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).

Conclusion: 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.