Assessment Of Tear Film Sub-Layer Thickness And Diagnosis Of Dry Eye Disease Using The Tear Film Imager

This study aimed to evaluate tear film sublayers using the Tear Film Imager (TFI), to distinguish between individuals with dry eye disease (DED) and healthy controls, and to assess the reliability of the measurements. The TFI device uses a single, non-invasive hyperspectral tear film measurement for 40 seconds to precisely evaluate the lipid and muco-aqueous layers of the tear film and their changes during blinking.

Prospective clinical study in a tertiary eye care center

A prospective comparative study was conducted with 28 subjects diagnosed with DED at a tertiary eye care clinic in Israel and 25 normal control subjects. DED diagnosis was made based on the OSDI questionnaire, corneal fluorescein staining, Schirmer test, and tear film break-up time. Quantified outputs from TIF were obtained, including muco-aqueous layer thickness (MALT), MALT rate of change (MALTR), lipid layer thickness (LLT), lipid break-up time (LBUT), and lipid map uniformity (LMU). The repeatability of the measures was also assessed.

The TFI measurements showed excellent test-retest repeatability (with measurements taken 85 ± 40 minutes apart) for the TFI measured parameters of MALT (Pearson correlation 0.78, P < 0.001) and LLT (Pearson correlation 0.68, P < 0.001). Differentiation levels were established between individuals with DED and those without: an aqueous deficiency DED would be diagnosed if MALT < 1,900 nm; MALTR < 100nm/s; lipid-related DED would be diagnosed for LBUT ≤ 7s, LMU ≥ 60nm2, LLT ≥ 69nm or a report of double lipid layer. Short-blink DED would be diagnosed for IBI (inter-blink interval)  ≤ 2s.

The study demonstrated that the TFI has good reproducibility and may assist in differentiation between individuals with DED and healthy controls. Further research is necessary to determine the TFI's usefulness for dry eye disease management and the treatment of other eye conditions.