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Rayanne Luke, Johns Hopkins University, Parameter Estimation for Tear Film Breakup
March 1, 2022 | 3:00 pm - 4:00 pm EST
Dry eye disease is caused by a breakdown of a uniform tear film, which occurs when the layer of tears experiences breakup. To better understand this ocular condition, the dynamics of the tear film can be studied using fluorescence imaging.
Many parameters affect tear film thickness and fluorescent intensity distributions over time; exact values or ranges for some are not available. We conduct parameter estimation by fitting to experimental fluorescent intensity data gathered from normal subjects’ tear films in vivo. The fitting is done with thin film fluid dynamics models for tear film thickness, osmolarity (saltiness), and fluorescein concentration. The corresponding fluorescent intensity is computed from the tear film thickness and fluorescein concentration. The parameters are determined by a least squares minimization between computed and experimental fluorescent intensity.
Results vary across subject trials. Optimal values for variables that cannot be measured in vivo within tear film breakup often fall within accepted experimental ranges for related tear film dynamics; some instances suggest a wider range of parameter values may be acceptable. This method can estimate parameters in a variety of breakup instances, which may lead to better understanding of dry eye.