Duplex Tear Film Evaporation Analysis

Abstract

Tear film thinning, hyperosmolarity, and breakup can cause irritation and damage to the human eye, and these form an area of active investigation for dry eye syndrome research. Recent research demonstrates that deficiencies in the lipid layer may cause locally increased evaporation, inducing conditions for breakup. In this paper, we explore the conditions for tear film breakup by considering a model for tear film dynamics with two mobile fluid layers, the aqueous and lipid layers. In addition, we include the effects of osmosis, evaporation as modified by the lipid, and the polar portion of the lipid layer. We solve the system numerically for reasonable parameter values and initial conditions and analyze how shifts in these cause changes to the system's dynamics.

Mathematical modelling of glob-driven tear film breakup

“…The rupture of a hypothesized mobile precorneal mucus coating of 20-50 nm over the ocular epithelial surface was investigated by Zhang et al (2004); their results indicated that, for a thin mobile mucus layer, van der Waals forces act significantly to disrupt the mucus layer and the corresponding TBUT matches the clinical TBUT for a dry eye and a healthy eye. Recently, Stapf et al (2017) studied a model with two mobile Newtonian fluid layers, one an aqueous layer and the other the lipid layer, i.e. adapted from the prior model of Bruna & Breward (2014).…”

Parameter Estimation for Mixed-Mechanism Tear Film Thinning

“…The glycocalyx could be modeled as a porous medium instead of using a no slip condition at the ocular surface; this could promote breakup at shorter times for smaller spots (Nong and Anderson 2010). A two layer model for the TF system could also be used (see Bruna and Breward 2014;Stapf et al 2017), and the fit could be conducted over two spatial dimensions.…”

Dynamics of Fluorescent Imaging for Rapid Tear Thinning

“…Simultaneous imaging of the tear film aqueous and lipid layers is a very valuable direction for future experimental work (King-Smith et al, 2013b, 2018). Developing mathematical models in parallel that include both aqueous and lipid layers is desirable as well (Bruna and Breward, 2014; Peng et al, 2014; Stapf et al, 2017).…”

“…The rupture of a hypothesized mobile precorneal mucus coating of 20–50 nm over the ocular epithelial surface was investigated by Zhang et al (2004); their results indicated that, for a thin mobile mucus layer, van der Waals forces act significantly to disrupt the mucus layer and the corresponding tear breakup time (TBUT) matches the clinical TBUT for a dry eye and a healthy eye. Recently, Stapf et al (2017) studied a model with two mobile Newtonian fluid layers, one is an aqueous layer and the other is the lipid layer, that is adapted from the prior model of Bruna and Breward (2014). This model has shown that the Marangoni effect due to lipid defects can reduce the lipid layer thickness, which subsequently allows elevated evaporation and then TBU.…”