Tear film dynamics in breakup with a rough ocular surface

Braun, RichardExperimental images of the tear film have been found to contain areas of rough texture. For long interblink times, the rough areas become more pronounced. We model tear film dynamics during the interblink. As the film thins to a critically low thickness, tear breakup (TBU) occurs. We hypothesize that the rough areas in experimental imaging are artifacts of the corneal surface, visible during TBU. To explore our hypothesis, we use one-dimensional thin film equations to model tear film fluid flow, and model the corneal surface as a sinusoidal function to account for its roughness. We use Fourier spectral methods to discretize in space and solve the resulting differential algebraic system using backward differentiation methods in Matlab. We parametrically study the effect of corneal surface features and of wetting forces on the tear film dynamics at TBU. Our results suggest that tear film rippling occurs at, but not before, TBU, and they support the interpretation of rough texture in experimental imaging as evidence of corneal surface roughness appearing during TBU.University of Delaware, Department of Mathematical SciencesM.S