Ophthalmic nanoemulsions that can treat the deficiencies of meibum (MGS) in Meibomian gland disease and restore its functionality in the tear film are greatly sought. The Rohto Dry Aid (RDA) formulation employs TEARSHIELD TECHNOLOGY^TM, which uses a multicomponent oil phase of polar and non-polar lipid-like molecules selected to mimic the profiles of healthy meibum. Thus, the interactions of RDA with “diseased” Meibomian (dMGS) films merit deeper analysis, as these interactions might offer important clues for both the development of new ocular formulations and the processes behind the therapeutic action of the nanoemulsions. Pseudobinary dMGS/RDA films were spread at the air–water surface of the Langmuir trough. Surface pressure-area isocycles and stress relaxations were used to access the layer’s response to blink-like cycling and dilatational viscoelasticity, respectively, while film morphology was recorded via Brewster angle microscopy. It was found that RDA is able to reverse the brittleness and to restore the stability of “diseased” MGS films and thus to revert the layer’s properties to the functionality of healthy Meibomian lipids. Therefore, in order to effectively treat dry eyes with MGS-oriented therapy, ophthalmic nanoemulsions warrant more research.

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.

Environmental stressors like low temperature, low relative humidity (RH), and particulate matter (PM2.5), promote tear film instability and dry eye disease. This study investigates how these conditions alter the interfacial behavior of meibomian gland secretion (MGS) films in vitro and evaluates the capacity of mucomimetic polymers (0.5% hyaluronic acid [HA], polyvinylpyrrolidone [PVP], and chondroitin sulfate [CHS]) to suppress these impacts. MGS films over polymer-containing aqueous subphases were analyzed using a Langmuir trough and Brewster angle microscopy under adverse conditions (20 °C subphase, 20% RH, PM2.5 exposure). A sophisticated analytical framework was developed to evaluate MGS duplex multilayers: (i) a Volmer equation-based 2D-VES model to probe interfacial molecular properties (limiting area, compressibility, cohesion pressure) and (ii) a combined Maxwell viscoelastic and diffusion-relaxation model to quantify the dilatational relaxation modulus. Results indicate that despite their distinct nature, environmental stressors similarly disrupt the multilayer structure, reorganization, and rheological properties of MGS layers during blink-like deformations. Polymer supplementation moderated these adverse effects, yielding partial recovery of film structure and isothermal reversibility. Distinct mechanisms of action for HA, PVP, and CHS at the film/aqueous interface are elucidated.