Abstract
PURPOSE: To assess the repeatability and reliability of different commercially available diagnostic platforms in the objective assessment of tear film parameters and if there exists any agreement between them. METHODS: Thirty healthy individuals (N = 60 eyes) and fifteen DED patients (N = 30 eyes) had their tear film parameters (Lipid layer thickness (LLT), Tear meniscus height (TMH), Non-invasive tear break up time (NIBUT)) assessed using three instruments - LipiView® II, IDRA ocular surface analyser (IDRA-OSA) and Oculus keratograph 5 M (K5M). Bland-Altman analysis and linear mixed effects modelling & Generalized Linear Hypothesis Test were used for analysis and coefficient of variation (CoV). RESULTS: There is poor repeatability but good reproducibility of LLT values measured with Lipiview, or IDRA. NIBUT using K5M & IDRA-OSA shows good repeatability and reproducibility in control group but poor repeatability in DED patients. TMH values obtained with K5M or IDRA-OSA had poor repeatability with high CoV. Between two observers, good reproducibility is observed for TMH and NIBUT values using both K5M & IDRA-OSA but not for LLT values. Between instruments, all the measurements (LLT, NIBUT and TMH) were significantly different on Bland Altman analysis. CONCLUSION: No two dry eye diagnostic platforms can be used interchangeably and non-invasive tear film values should be interpreted keeping in mind the individual machine's variability. The high coefficient of variation in DED patients compared to normal reflects inherent variability in tear film irrespective of the device used.