ASSESSMENT OF TEAR FILM BREAKUP USING NONINVASIVE I-TRACE TECHNOLOGY IN NORMAL AND DRY EYE PATIENTS

To evaluate the correlation of Noninvasive Tear Breakup Time (NIBUT) and Tear Film Index (TFI) as measured with iTrace technology with Fluorescein Breakup Time (FBUT) as well as the correlation between NIBUT and other clinical signs and dry eye symptoms.  

University of Crete, Medical School, Institute of Vision and Optics. 

This prospective and comparative study involved healthy volunteers. Only the right eye from each participant was included in the study. Inclusion criteria to participate in the study were no ocular surgeries within last year, no conjunctival or corneal inflammation, no use of contact lenses during the last 7 days, no history of ocular trauma, no ocular surface disease, no use of artificial tears within the week prior to examination and no systemic disease known to affect the eye. The participants were categorized into 2 groups depending on their Ocular Surface Disease Index (OSDI) score (0-12: Normal, >13: Dry eye disease). The assessment of the NIBUT and TFI was performed right after the participant history was obtained, followed by the OSDI questionnaire, tear meniscus height measurement using Optical Coherence Tomography (OCT), slit-lamp examination, tear film FBUT measurement, fluorescein corneal staining score on the Oxford scale and Schirmer I test. The subsiding of reflex tearing was achieved by a 15-minute break between NIBUT, FBUT and Schirmer I test measurements.

The study included 60 eyes from 60 patients. Tearfilm break up time was substantially longer for all subjects when performed invasively using a fluorescein strip compared to non-invasively using iTrace (NIBUT mean = 8.30 ± 2.48 seconds, P=0.7502, vs FBUT mean = 11.14 ± 4.79 seconds, P=0.01532). No statistically significant difference was found for the NIBUT measurements between the normal and the dry eye disease subjects (8.21 ± 2.59 vs 8.39 ± 2.40, P = 0.7502) However, the difference between the two groups for the FBUT was statistically significant (12.42 ± 5.13 vs 9.87 ± 4.11, P = 0.01532). In addition, within a significance level of 95%, there was a significant positive correlation between NIBUT mean and FBUT mean (P = 0.01872). In the normal-control group, no statistically significant correlation was found between any of the parameters. However, in the analysis of the dry eye group there was a statistically significant positive correlation between the OSDI and the TFI (P = 0.04866).  

This study indicates that FBUT shows significantly longer tear film breakup times than NI-BUT via iTrace, with FBUT effectively distinguishing between normal and dry eye disease groups, unlike NI-BUT. Although NI-BUT showed a positive correlation with FBUT, its’ limited ability to differentiate severity suggests it may be less reliable as a stand-alone diagnostic tool for dry eye disease. Additionally, the positive correlation between TFI and OSDI in the dry eye group suggests that TFI may serve as a useful index for assessing dry eye symptoms.