Manual Interferometric Device Accurately Measures Tear Breakup Time

A portable and inexpensive lipid layer examination instrument demonstrates high diagnostic accuracy for measuring tear breakup time (TBUT), according to a study published in Contact Lens and Anterior Eye.

Researchers enrolled 108 patients (71% women, median age, 61 years) in a cross-sectional study consisting of individuals with dry eye disease (DED; n=57) and control individuals (n=51). Participants completed a Schein questionnaire, a disease-specific 6-item questionnaire which grades the frequency of dry eye symptoms on a scale from 0 to 4 (0, none; 4, all the time). Investigators performed non-invasive tear break-up time (NIBUT), fluorescein tear film break-up time (FBUT) and fluorescein surface straining and a second examiner confirmed these measurements.

Participants with DED had significantly shorter NIBUT compared with control individuals (P <.001) and no difference was noted between the 3 NIBUT measurements taken of both eyes in either group (DED: P =.115; Controls: P =.081).

NIBUT had a significant negative correlation with age (P =.033), female sex (P =.005), and dry eye symptoms as indicated by the Schein questionnaire (P <.001). The NIBUT had a significant positive correlation with TBUT (P <.001).

The area under the receiver operating characteristic curve (AUC) was 0.944, indicating high diagnostic accuracy for the device. Using a cutoff value of 12 seconds, NIBUT demonstrated a 90.2% sensitivity (95% CI, 76.9%-97.3 %), 88.5% specificity (95% CI, 69.9%-96.6%), 92.5% positive predictive value (95% CI, 80.9%-97.3%) and 85.2% negative predictive value (95% CI, 69.2%-93.7%).

“NIBUT measured using the handheld lipid layer examination instrument detected DED with high sensitivity and specificity. It showed great consistency with dry eye signs and symptoms and was a confident indicator, predictor, and discriminator of DED,” the study authors note. “Also, since instilling standard Fluorescein to perform TBUT hinders the consequent application of soft contact lenses, this diagnostic procedure might be particularly useful in contact lens practice.”

Study limitations include the use of the Schein questionnaire, which has no validated cutoff for DED, and the inability of the device to analyze the entire corneal surface at once.