Evaluation of incomplete blinking as a measurement of dry eye disease

Purpose: To investigate the association between partial blinking during spontaneous blinking as measured by interferometry and ocular exams for the assessment of dry eye disease (DED). Methods: This retrospective study included 58 eyes of patients previously diagnosed with DED. Ocular surface assessment included ocular surface disease index (OSDI) score, tear film osmolarity, tear breakup time (TBUT), grading of corneal fluorescein staining, Schirmer I test, and dry eye parameters by the LipiView (TM) interferometer (TearScience, Morrisville, NC, USA), including lipid layer thickness of the tear film (LLT), meibomian gland dropout (MGd), number of incomplete and complete blinks per 20 s and the partial blinking rate (PBR). Generalized estimation equations (GEE) were used for association testing between each variable of interest. The working correlation for each GEE model was selected using the Corrected Quasi-likelihood under the Independence Model Criterion. Results: The number of incomplete blinks was significantly associated with TBUT (P = 0.006), OSDI (P = 0.000) and MGd (P = 0.000). PBR was significantly associated with OSDI (P = 0.032) and MGd (P = 0.000). The number of complete blinks was significantly associated with TBUT (P = 0.032), but not with other ocular surface parameters. MGd was significantly associated with TBUT (P = 0.002) and OSDI (P = 0.001). LLT was significantly associated with tear film osmolarity (P = 0.007), and tear film osmolarity was significantly associated with LLT (P = 0.000). Conclusions: Incomplete blinking is associated with decreased TBUT, increased OSDI, and increased MGd possibly through its contribution to meibomian gland obstruction and subsequent loss of tear film homeostasis. It may, therefore, be considered an additive measure for mild-to-moderate DED assessment.