Tear interferometric patterns reflect clinical tear dynamics in dry eye patients

PURPOSE. We investigated whether the tear interferometric pattern was able to identify differences in tear film kinetics among clinical subtypes of dry eye. METHODS. A total of 138 eyes of 76 subjects (38 men and 38 women; mean age ± SD, 61.6 ± 16.2 years) with or without dry eye who visited Itoh Clinic from May to August 2015 were enrolled in a cross-sectional study. Clinical diagnosis of dry eye subtype was based on tear film parameters. The pattern of tear film kinetics determined by interferometry was classified as 0 (monotonous gray or multicolor interferometric fringe with a noninvasive breakup time [NIBUT] of ≥5 seconds), 1 (multicolor interferometric fringe with a NIBUT of <5 seconds), or 2 (grayish amorphous interferometric fringe with a NIBUT of <5 seconds), and reliability of classification was evaluated. Lipid layer thickness (LLT) for the tear film was also determined by interferometry. RESULTS. Interrater κ values for evaluation of interferometric patterns ranged from 0.57 to 0.94 for both physicians and nonphysicians with reference to a dry eye expert, the latter of whom showed an intrarater reliability of 0.90. The distribution of eyes among interferometric patterns 0, 1, and 2 coincided well with the clinical subgroups of normal tear condition, non– Sjögren syndrome aqueous-deficient dry eye, and meibomian gland dysfunction, respectively. A multicolor interferometric fringe was essentially observed only at an LLT of >70 nm. CONCLUSIONS. Tear interferometry was able to reliably distinguish clinical subtypes of dry eye by reflecting the balance between the lipid and aqueous layers of the tear film.