Correlation between tear osmolarity and tear meniscus

Abstract

Purpose. To examine the relationship between tear meniscus height (TMH) and subjective meniscus grading (subjective TM) with tear osmolarity. Methods. Tear osmolarity measurements (using TearLab) and digital images of the tear meniscus were obtained in 177 consecutive patients undergoing an eye examination at our optometry clinic (Universidad de Santiago de Compostela, Spain) who fulfilled the study's inclusion criteria. Participants were also administered the McMonnies and Ocular Surface Disease Index (OSDI) questionnaires for the detection of dry eye disease. The lower tear meniscus was videotaped by a digital camera attached to a slit lamp in its central portion without fluorescein instillation. After the study, a masked observer extracted an image from each video, and measured the TMH using open source software (NIH ImageJ). Subsequently, the masked observer subjectively graded the appearance of each meniscus. For statistical analysis, subjects were stratified by age and by dry eye symptoms as indicated by their scores in the two questionnaires. Results. In the whole study population, a significant relationship was observed between osmolarity and TMH (-0.41, p<0.001) and osmolarity and subjective TM (r = 0.35, p<0.001). A cluster analysis revealed similar correlations when subjects were stratified by age or dry eye symptoms, these correlations being more pronounced in older and more symptomatic individuals. Objective TMH measurements and subjective meniscus quality were also correlated (r=-0.75, p<0.001). Conclusions. Osmolarity and both objective TMH measurements and subjective interpretation of the meniscus showed high correlation, especially in older symptomatic subjects.