The most popular contact angle (CA)-based approaches for determination of solid surface free energy (SFE) are considered: (i) single liquid methods, mainly of Neumann and Chibowski, (ii) the multiple liquids approach of Owens–Wendt–Rabel–Kaelble (OWRK), and (iii) van Oss-Chaudhury–Good (vOCG) acid–base model. Evaluations based on Neumann and Chibowski models agree between each other. Under the assumption of equilibrium “wet wetting” (i.e., presence of saturated precursor film ahead of the drop), the model of Chibowski transforms in Lipatov’s interfacial equilibrium rule, i.e., the Antonow rule derived for the ternary point solid–liquid–gas. Very good agreement is observed between single and multiple liquids models where OWRK/vOCG values can be viewed as a mean of the individual SFE adopted by the solid with each of the wetting probes. Both approaches (single and multiple liquids) can be used in conjunction to evaluate SFE dispersion and polar components and to elucidate hydrophobicity and hydrophilicity. The implementation of apparently fully non-polar liquids (diiodomethane, bromonaphthalene) in OWRK and vOCG is practically and theoretically suspect. CA-based estimates represent apparent SFE determined by the interactions of both the solid surface and the probing liquid, which are very useful to elucidate the energy, chemistry and dynamics of the solid surface.

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.

The estimation of surface free energy (SFE) of a solid is a major issue in (bio)material and (bio)interfacial research. Here we show how combining Neumann and Gerson equations of state allows calculation of SFE and Girifalco-Good parameter (characterizing the interaction between the solid and the wetting liquid) analytically (in closed form) and in physically motivated fashion solely from the surface tension of the wetting liquid and its contact angle with the solid surface. This is significant enhancement compared to the traditional iterative solving of the equations of state or to their empirical fitting by high order polynomials. It is shown that the values of SFE calculated in closed-form fashion are in excellent agreement with the iteratively calculated ones and can open convenient opportunity for direct non-iterative computation of number of surface chemistry parameters.

Purpose . To compare the effectiveness of orthoptic training and prism correction in the management of convergence insufficiency (CI) among young adults. Material and methods . A prospective comparative clinical trial was conducted on 60 young adults aged 18–25 years diagnosed with CI. Participants were randomly assigned to Group A (orthoptic training; n =3 0) or Group B (prism correction; n = 30). Group A underwent 6 weeks of supervised orthoptic exercises (pencil push-ups, brock string, jump convergence, computer-based therapy), while Group B received base-in prisms prescribed according to Sheard’s criterion. Outcome measures included near point of convergence (NPC), positive fusional vergence (PFV), Convergence Insufficiency Symptom Survey (CISS), stereoacuity, and reading speed. Results . Group A showed significant improvement in NPC (13.5 ± 2.8 cm to 7.2 ± 1.8 cm; p < 0.001), PFV (12.4 ± 3.1 Δ to 22.8 ± 4.2 Δ; p < 0.001), and CISS score (31.6 ± 5.2 to 15.8 ± 4.0; p < 0.001). Group B demonstrated smaller improvements in NPC (13.3 ± 2.5 cm to 10.5 ± 2.2 cm; p = 0.002), PFV (12.1 ± 2.9 Δ to 14.5 ± 3.3 Δ; p = 0.04), and CISS (31.3 ± 5.5 to 22.6 ± 5.1; p < 0.001). Stereoacuity improved significantly in Group A (140 ± 35 arc sec to 80 ± 25 arc sec; p < 0.01), but not in Group B. Between-group comparisons confirmed superior outcomes in Group A across primary measures (p < 0.01). Conclusion . Both interventions were effective, but orthoptic training provided superior improvements in vergence parameters, symptom reduction, and stereoacuity. Prism correction may serve as an adjunct for immediate symptomatic relief, while orthoptic therapy should be prioritized for long-term management.