Environmental stressors such as low temperature, low relative humidity (RH), and airborne particulate matter (PM2.5) can promote tear film (TF) instability and dry eye disease. Because the lipid layer is the first TF component exposed to these challenges, this study investigates how such conditions alter the interfacial behavior of meibomian gland secretion (MGS) films in vitro. A second objective is to evaluate the capacity of Rohto Dry Aid (RDA), a tear-mimetic nanoemulsion, to suppress the impact of environmental stressors on MGS. Pseudobinary MGS/RDA films were studied with a Langmuir trough and Brewster angle microscopy to assess molecular-level interactions at the air–water interface under adverse ambient conditions, including 20 °C aqueous subphase, 20% RH, and PM2.5 exposure. It was found that despite their distinct nature, the environmental stressors exert similar impacts, disrupting the multilayer structure and the reorganization and rheological properties of MGS layers at blink-like area deformations. These adverse effects were moderated by the supplementation with RDA which resulted in partial recovery of the mebomian film structure and isothermal reversibility. Thus, although they cannot fully replicate the complexity of native meibum, tear-mimetic nanoemulsions represent a potent tool to mitigate the impact of environmental stressors on tear film functionality.
Eftimov et al. (2026) studied this question.