The Dry Eye Zone

Rebecca's Blog


Study: Physics and evaporation of the tear film

I don’t have the scientific background to say anything about the significance of this but it caught my eye because I really like when dry eye is looked at from fresh perspectives scientifically. Too much of dry eye has been reduced to discussions of inflammation and meibomian glands.

Crystalline Wax Esters Regulate the Evaporation Resistance of Tear Film Lipid Layers Associated with Dry Eye Syndrome. Paananen et al, J Phys Chem Lett. 2019 Jul 18;10(14):3893-3898.

Dry eye syndrome (DES), one of the most common ophthalmological diseases, is typically caused by excessive evaporation of tear fluid from the ocular surface. Excessive evaporation is linked to impaired function of the tear film lipid layer (TFLL) that covers the aqueous tear film. The principles of the evaporation resistance of the TFLL have remained unknown, however. We combined atomistic simulations with Brewster angle microscopy and surface potential experiments to explore the organization and evaporation resistance of films composed of wax esters, one of the main components of the TFLL. The results provide evidence that the evaporation resistance of the TFLL is based on crystalline-state layers of wax esters and that the evaporation rate is determined by defects in the TFLL and its coverage on the ocular surface. On the basis of the results, uncovering the nonequilibrium spreading and crystallization of TFLL films has potential to reveal new means of treating DES.