Settling characteristics of scleral lenses in Chinese adults with refractive error.

PURPOSE: To investigate the settling characteristics of a scleral lens in Chinese adults with refractive error and to provide guidance for its clinical application. METHODS: A total of 21 healthy Chinese adults (27.2 ± 4.1 years) with refractive error were enrolled in this study. The average spherical equivalent was -5.50 ± 2.92 D. Subjects were fitted with 15.6 mm diameter scleral lenses. The central post-lens tear thickness (PoLTT) was measured immediately after lens placement, 30, 60, 120, and 240 min after lens insertion at the dispensing visit and immediately after lens placement and 240 min after three months through optical coherence tomography. Statistical analyses were conducted using repeated measures analysis of variance and paired-t test. RESULTS: At the dispensing visit, the amount of settling after 240 min of lens wear was 126 ± 33 µm. After three months, the amount of settling was 98 ± 55 µm after 240 min. No significant difference was detected in the PoLTT immediately after lens placement between the dispensing visit and after three months (t = -0.246, p = 0.807), while a significant difference was noted at 240 min after lens insertion (t = -6.575, p < 0.001). The amount of settling was higher at the dispensing visit than that after three months (average difference = 28 ± 63 µm, t = 2.733, p = 0.01). The prediction model of PoLTT over time was y = 26.263-0.690 × t + 0.001 × t2 + 0.926 × y30 (R2 = 0.939), where y denotes the predicted PoLTT at t min after lens insertion, y30 denotes the PoLTT at 30 min after lens insertion. CONCLUSION: For the investigated small-diameter scleral lens (material: Boston XO, diameter: 15.6 mm, four-zone and periphery toric design), the PoLTT decreased over time after lens insertion in Chinese adults with refractive error, and the amount of settling varied among individuals (range: 71-204 µm). The amount of settling did not increase further after three months, indicating the long-term fitting stability of the scleral lens. Practitioners could estimate the PoLTT using the prediction model based on the PoLTT at 30 min after wearing lenses.

Metrics of Anterior Sclera in Normal Chinese Adults: Anterior Segment Imaging Using the Swept-Source Optical Coherence Tomography.

PURPOSE: To measure the corneoscleral limbus and anterior sclera parameters of normal Chinese adults by swept-source optical coherence tomography (OCT). MATERIALS AND METHODS: In this cross-sectional study, a total of 56 Chinese subjects with ametropia were evaluated in the Eye Hospital of Wenzhou Medical University from September 2020 to December 2020, including 26 (46.4%) men, with an average age of 24.7±1.8 years old. The OCT SS-1000 (CASIA, Tomey, Tokyo, Japan) was used to measure the sagittal height, corneoscleral junction (CSJ) angle, and scleral angle. RESULTS: The chord was across the corneal center and the line connecting the center of the cornea and the center of the chord was perpendicular to the chord. The mean sagittal height at chord lengths of 10.0, 12.3, and 15.0 mm were 1,756±72, 2,658±110, and 3,676±155 µm, respectively. The absolute values of the differences between horizontal and vertical meridians at three chord lengths were 54±40, 70±67, and 117±95 µm, respectively. One-way analysis of variance showed that the differences of CSJ angles at 12.3-mm chord and scleral angles at 15.0-mm chord in the four segments were statistically significant ( F values were 32.01 and 13.37, respectively, both P <0.001). The CSJ angles from low to high were 176.53±2.14° (nasal), 178.66±1.84° (inferior), 179.13±1.20° (temporal), and 179.31±1.68° (superior), and 87.5% of the nasal angles were less than 179°. The scleral angles from high to low were 38.35±2.47° (temporal), 38.26±3.37° (superior), 35.37±3.10° (nasal), and 35.30±4.71° (inferior). CONCLUSIONS: The morphology of corneoscleral limbus and anterior sclera is asymmetrical in normal Chinese adults. The nasal side of the corneoscleral limbus has the largest angle, and the superior and temporal sides of the scleral angle are larger.

Low vision aids and age are associated with Müller-Lyer illusion in congenital visually impaired children.

Background: The correlation between visual impairment and Müller-Lyer illusion is not yet elucidated. This study aimed to explore the connection between visual status, age, and the intensity of Müller-Lyer illusion in congenitally visually impaired and visually healthy children aged 4-17 years. Additionally, the developmental trends were compared. Methods: This cross-sectional study included 125 visually impaired children (age: 10.59 ± 4.05 years), among them, 53 had utilized low vision aids (LVAs) and 133 healthy controls (age: 11.33 ± 3.39 years). The participants were presented with Müller-Lyer illusion stimuli via binocular and engaged in a two-alternative forced choice task to quantify the illusion intensity. Pertinent factors including age, gender, residence, binocular distant best-corrected visual acuity and LVAs usage history, were assessed. Results: The visually impaired group exhibited significantly elevated illusion intensity compared to the healthy group (9.74 ± 2.89% vs. 5.42 ± 3.81%, p < 0.001), and visually impaired participants who had used LVAs exhibited significantly lower intensity compared to those had not (9.13 ± 3.00% vs. 10.19 ± 2.74%, p = 0.043). Multivariate generalized estimation equations revealed that visual impairment [odds ratio (OR) = 2.75, p < 0.001] and age (OR = 0.60, p < 0.001) were associated with illusion intensity in all participants, while history of LVAs usage (OR = 0.49, p = 0.045) and age (OR = 0.61, p < 0.001) were negatively correlated in visually impaired group. A significantly negative correlation was found between illusion intensity and age 4-17 years in the subgroups of visually impaired who had used LVAs (Y = -0.54X + 15.06, R2 = 0.56), who had not used (Y = -0.49X + 15.24, R2 = 0.51), and healthy controls (Y = -0.50X + 11.18, R2 = 0.21); all p-values were < 0.001. Conclusion: Children aged 4-17 years afflicted with congenital visual impairment exhibited a heightened intensity of Müller-Lyer illusion compared to visually normal counterparts, LVAs usage experience could reduce this higher intensity. The developmental trajectory of illusion intensity declined consistently with age across all three groups. The abnormal visual experiences during early-life may adversely affect integration in congenitally visually impaired children, and LVAs could facilitate this functional development.

Bioinspired Self-Standing, Self-Floating 3D Solar Evaporators Breaking the Trade-Off between Salt Cycle and Heat Localization for Continuous Seawater Desalination.

Facing the global water shortage challenge, solar-driven desalination is considered a sustainable technology to obtain freshwater from seawater. However, the trade-off between the salt cycle and heat localization of existing solar evaporators (SE) hinders its further practical applications. Here, inspired by water hyacinth, a self-standing and self-floating 3D SE with adiabatic foam particles and aligned water channels is built through a continuous directional freeze-casting technique. With the help of the heat insulation effect of foam particles and the efficient water transport of aligned water channels, this new SE can cut off the heat transfer from the top photothermal area to the bulk water without affecting the water supply, breaking the long-standing trade-off between salt cycle and heat localization of traditional SEs. Additionally, its self-standing and self-floating features can reduce human maintenance. Its large exposure height can increase evaporation area and collect environmental energy, breaking the long-standing limitation of solar-to-vapor efficiency of conventional SEs. With the novel structure employed, an evaporation flux of 2.25 kg m-2 h-1 , and apparent solar-to-vapor efficiency of 136.7% are achieved under 1 sun illumination. This work demonstrates a new evaporator structure, and also provides a key insight into the structural design of next-generation salt-tolerant and high-efficiency SEs.

Supercritical Fluid Microcellular Foaming of High-Hardness TPU via a Pressure-Quenching Process: Restricted Foam Expansion Controlled by Matrix Modulus and Thermal Degradation.

High-hardness thermoplastic polyurethane (HD-TPU) presents a high matrix modulus, low-temperature durability, and remarkable abrasion resistance, and has been used in many advanced applications. However, the fabrication of microcellular HD-TPU foam is rarely reported in the literature. In this study, the foaming behavior of HD-TPU with a hardness of 75D was investigated via a pressure-quenching foaming process using CO2 as a blowing agent. Microcellular HD-TPU foam with a maximum expansion ratio of 3.9-fold, a cell size of 25.9 µm, and cell density of 7.8 × 108 cells/cm3 was prepared, where a high optimum foaming temperature of about 170 °C had to be applied with the aim of softening the polymer's matrix modulus. However, the foaming behavior of HD-TPU deteriorated when the foaming temperature further increased to 180 °C, characterized by the presence of coalesced cells, microcracks, and a high foam density of 1.0 g/cm3 even though the crystal domains still existed within the matrix. The cell morphology evolution of HD-TPU foam was investigated by adjusting the saturation time, and an obvious degradation occurred during the high-temperature saturation process. A cell growth mechanism of HD-TPU foams in degradation environments was proposed to explain this phenomenon based on the gas escape through the defective matrix.