Search Results (5,708)

Silica aerogel, a prototypical transparent nanoporous material with ultralow density and a widely tunable refractive index, is employed as a Cherenkov radiator for precision gamma-ray diagnostics in inertial confinement fusion experiments. However, its optical transmittance is highly sensitive to sol–gel chemistry. Here, silica aerogels were prepared from tetraethyl orthosilicate (TEOS), ethanol, water, and aqueous ammonia, followed by aging, solvent exchange, and supercritical drying. The study examined how catalyst, ethanol, and water concentrations regulate nanostructure and optical transmittance. Increasing ammonia content accelerated gelation, produced smaller framework particles, and enlarged the pore size and pore volume. These changes increased the transmittance at 550 nm from 79.6% for C1 to 84.9% for C7. Increasing ethanol concentration diluted TEOS and its hydrolysis products, extended gelation, and narrowed the particle-size distribution. The average particle size decreased from 21.79 to 17.01 nm, while the transmittance at 550 nm increased from 57.4% for E1 to 65.2% for E5. Water produced a non-monotonic response: insufficient water limited TEOS hydrolysis, whereas excessive water promoted structural heterogeneity. Intermediate water content provided the most favorable optical response. These findings define a process–structure–transmittance relationship in which formulation-dependent nanoscale network formation governs scattering losses and optical clarity. Full article

In this work, we present a case study mainly from Raman lidar observations and radiosonde data for a site in the European Arctic to analyse how aerosol grows into a purely water-containing fog. We use a relatively high resolution (85 s, 7.5m) for the lidar evaluation and use an inversion technique to derive aerosol size distributions before fog formation, in the fog and directly after fog disintegration. We find predominantly accumulation-size particles before and after the fog event. In the fog layer, this mode splits up into two branches: one is hydrophobic, and the other roughly doubles its size within 85 s but does not grow into typical cloud droplet sizes. We find very high lidar ratios > 100 sr for 532 nm. We use Mie calculations to confirm that such high lidar ratios are to be expected for micron-sized droplets if the imaginary part of the refractive index is not negligible. Further, we analyse how lidar ratio and colour ratio change as a function of cloud optical depth and derive that the formation and disintegration of several short-lived fog events at the same altitude seem to be symmetrical. Finally, we employ Koehler theory to show that the droplets should have grown into super-micron sizes. As this has not been observed clearly, the time for particle growth into cloud regime under low turbulence conditions takes longer than 85 s. Full article

Purpose: We aimed to compare the real-world effectiveness of four myopia-control spectacle lens interventions for childhood myopia control using a doubly robust causal inference framework. Design: This was a retrospective cohort study with multi-treatment augmented inverse probability weighting. Participants: A total of 2764 myopic children (right eyes) aged 3–18 years were included, screened from 13,071 electronic medical records at Ineye Hospital, Chengdu University of Traditional Chinese Medicine, between January 2023 and January 2026. Methods: Participants were allocated to four myopia-control spectacle lens groups and one single-vision spectacle lens group: Higher-Order Aberration Defocus (n = 912), Defocus Incorporated Multiple Segments (n = 800), Highly Aspherical Lenslets (n = 476), Diversified Segmental Defocus Optimization (n = 238), and single-vision lenses (n = 338). A doubly robust estimator combining multinomial propensity-score weighting with outcome regression was applied to adjust for confounding. Outcome Measures: The primary outcomes were one-year changes in axial length and spherical equivalent. The secondary outcomes were the rates of rapid progression. Treatment-effect heterogeneity was explored across prespecified baseline age, refractive error, and axial length subgroups. Results: After adjustment, all four myopia-control designs significantly outperformed single-vision correction (p < 0.05). The design based on Higher-Order Aberration Defocus demonstrated the greatest efficacy, with an axial length change of 0.107 mm and a spherical equivalent change of −0.146 D. Within this group, 25.5% of children exhibited rapid axial elongation (≥0.36 mm/year) and 8.3% exhibited rapid myopic progression (≥−0.50 D/year). The treatment effect was statistically significant in children with low myopia or an axial length no greater than 26 mm (p < 0.05), but not in those with high myopia or pathological axial elongation. Conclusions: All four myopia-control spectacle lens designs demonstrated significant advantages over single-vision correction in real-world clinical practice. Particular emphasis should be placed on the role of myopia-control spectacles during the early stages of myopia. As myopia progresses to high myopia or pathological axial elongation, the efficacy of myopia-control spectacle lenses as a standalone intervention diminishes, and combined approaches incorporating multiple myopia management strategies may be warranted. Full article

Despite recent advances in computer vision and optical imaging, the image-based recognition of ophthalmic lens categories characterized by different refractive indices and anti-reflective coating types remains largely unexplored. In this work, we formulate this problem as a non-destructive optical inspection task, where lens-induced visual changes are treated as subtle micro-texture signatures produced by the interaction between the lens and a controlled visual target. Although these signatures are often imperceptible to the human eye, they can be quantified using local texture analysis. To establish the first systematic benchmark for this emerging application, we present a comprehensive evaluation of state-of-the-art local texture descriptors, with particular emphasis on Local Binary Pattern (LBP)-like methods, under unified evaluation protocols. The evaluation is conducted on two dedicated ophthalmic lens image datasets acquired under controlled conditions, using consistent visual targets designed to reveal lens-induced texture and color variations. This setting enables a rigorous assessment of whether handcrafted micro-texture descriptors can capture discriminative image signatures associated with different refractive indices and anti-reflective coating types. The experimental results demonstrate that several modern LBP variants provide excellent recognition performance, confirming the relevance of local micro-texture analysis for image-based ophthalmic lens category recognition. Comparisons with pretrained deep feature extractors further show that although deep representations generally achieve the highest recognition rates, several handcrafted descriptors offer comparable performance while requiring neither network training nor fine-tuning. Beyond recognition accuracy, the benchmark investigates performance stability across datasets, robustness under limited training samples, classifier influence, and the statistical significance of the observed performance differences. Overall, this work establishes the first reproducible image-based benchmark for non-destructive ophthalmic lens inspection and provides practical guidelines for selecting local texture descriptors in ophthalmic lens recognition systems. Full article

Vanadium dioxide (VO₂) is a prominent active material for reconfigurable nanophotonics because its reversible metal-insulator transition produces large changes in complex refractive index and electrical conductivity. The usable phase contrast, however, is not an intrinsic constant: it is governed by defect type and location, vanadium valence, oxygen stoichiometry, strain, crystallographic orientation, dimensionality, and the chemical, electrical, optical, and thermal boundary conditions imposed by interfaces. This focused narrative review develops a defect- and interface-centred framework linking VO₂ phase physics to device-level optical modulation. Bulk, surface, grain-boundary, and heterointerface defects are distinguished, together with their effects on carriers, V-V bonding, phase stability, optical loss, and cycling reliability. Epitaxial and polycrystalline films, ultrathin layers, and nanostructures are compared across the visible, near-infrared, mid-infrared, and terahertz ranges. Thermal, optical, electrical, electrostatic, electrochemical, ionic, strain, and ferroelectric activation pathways are then compared according to volatility, speed, retention, reversibility, and endurance. Representative free-space metasurfaces, guided-wave modulators, adaptive emitters, and photonic memories are benchmarked separately to avoid mixing incomparable performance definitions. The resulting analysis shows that optical modulation, insertion loss, thermal overhead, ambient stability, and endurance are coupled through the same defect and interface landscape. Progress, therefore, requires coordinated control of phase purity, local chemistry, interface energetics, thermal transport, and architecture-specific performance reporting. Full article

Background/Objectives: Myopia is a major global public health concern, particularly in East Asia. Taiwan’s exceptionally high prevalence of childhood myopia provides a valuable population model for investigating refractive development and prevention. This study examined geographic disparities in visual acuity, refractive errors, and optometric resources among Taiwanese elementary school children. Methods: This retrospective nationwide study analyzed anonymized screening data from 10,610 elementary school children collected from 2014 to 2023. Children were classified as urban, rural, remote, or especially/extremely remote according to governmental criteria. Comprehensive vision examinations were performed by licensed optometrists. Refraction was assessed using autorefraction and retinoscopy without cycloplegia. Refractive errors and healthcare resources were compared across regions using multivariable logistic and linear regression analyses. Results: Myopia was present in 86.4% of male and 87.0% of female children, while measurable astigmatism (≥0.25 D) was present in 98.4% of both sexes. High myopia and high astigmatism affected 2.3% and 4.5% of children, respectively. Myopia prevalence varied across grade levels and was 88.9% among sixth-grade children. Compared with urban children, those living in especially or extremely remote areas and rural areas had higher odds of measurable astigmatism (OR = 2.81 and 1.63, respectively; p < 0.01). Rural children had significantly lower odds of myopia, while no significant association with myopia was observed among children living in specially or extremely remote areas. Optometry clinics were more concentrated in urban areas, and a higher density of optometry clinics was associated with lower odds of myopia. Conclusions: Taiwan provides a valuable model population for understanding geographic, environmental, and healthcare-related factors in childhood myopia. Better visual acuity does not necessarily indicate lower refractive risk. Region-specific strategies should strengthen comprehensive screening and referral, improve optometric access and affordable correction in remote areas, and promote lifestyle and environmental interventions in urban settings. Full article

This work presents an experimental investigation of droplet evaporation dynamics using a step-index multimode fiber-tip (MMF) interferometer. Distilled water, ethanol, isopropyl alcohol (IPA), and their binary mixtures with water were analyzed through complementary frequency- and time-domain approaches. Fast Fourier Transform (FFT) analysis was used to identify the dominant spectral components over selected evaporation intervals, while the instantaneous phase obtained from the analytic signal was used to track time-dependent variations in the optical response. For water, dominant components at 8.34 and 9.87 Hz corresponded to thickness-variation rates of −4.85 and −5.75 µm/s, respectively. Ethanol exhibited a dominant component at 15.8 Hz, corresponding to −9.01 µm/s, whereas IPA showed components at 13.2 and 34.8 Hz, associated with rates of −7.46 and −19.6 µm/s. Binary mixtures exhibited multiple spectral components and stronger temporal variability, indicating a nonstationary optical response during evaporation. The frequency- and time-domain results therefore provide complementary descriptions: the FFT identifies the dominant components over the selected interval, whereas instantaneous-phase analysis reveals their temporal evolution. Because the analysis was performed over short, selected evaporation intervals, the refractive index was assumed to remain approximately constant, and the measured phase variations were therefore attributed predominantly to changes in droplet thickness. The retrieved values are consequently interpreted as thickness-variation rates rather than direct mass-loss rates. The proposed approach provides a simple and compact method for monitoring droplet evaporation. Full article

Background: Opaque bubble layers (OBLs) are a common intraoperative complication during flap creation in femtosecond laser-assisted LASIK (FS-LASIK). This study aims to evaluate how cone and flap sizes can be optimized to minimize OBL risk in VISUMAX 800 FS-LASIK. Methods: This was a retrospective chart review of patients who underwent LASIK with the VISUMAX 800. Eyes were grouped by cone size and laser settings into S cone/M settings and M cone/L settings, in addition to OBL status (OBL vs. non-OBL). Generalized estimating equations were used to account for inter-eye correlation. Flap–cone edge gap was quantified from intraoperative images using FIJI (version 2.17.0, ImageJ). Results: OBL developed in 17 of 226 eyes (7.5%). The majority of OBLs (15/17) occurred in the M cone with L setting group. Eyes that developed OBLs had larger WTWs (p < 0.001) and larger mean flap diameters (p < 0.001). Among eyes with M cones and L settings, image analysis revealed that the average gap between flap and cone edge was significantly larger in the OBL group (p = 0.007). Conclusions: Our findings support the use of VISUMAX 800 in FS-LASIK and suggest that OBL formation may be associated with the distance between flap and cone edges, with larger average flap–cone gaps observed in eyes that developed OBL. Full article

Aquatic heavy metal pollution poses substantial risks to ecological systems and human health, attributable to the toxic properties and bioaccumulative behaviors of metallic ions, including Hg[II], Zn[II], and ion mixtures. A novel SPR sensing chip based on a Ag-BiFeO₃-MoS₂–graphene hybrid structure is proposed and analyzed for detection of metal ion mixtures. Systematic tuning is implemented for Ag and BiFeO₃ film thicknesses to boost the overall sensing capability, aiming to acquire minimized reflectance together with favorable detection sensitivity. Following this step, we investigate how different quantities of MoS₂ and graphene layers affect the sensing properties of the SPR biosensor. Analytical outcomes demonstrate that configurations adopting monolayer MoS₂ and graphene achieve the maximum phase sensitivity. Moreover, the optimized SPR chip architecture achieves sensing sensitivity two orders of magnitude greater than conventional sensor setups. Numerical investigations are further carried out to evaluate the sensor’s response toward various heavy metal ion species. The maximal sensitivity of 1.599 × 10⁶ deg/RIU is realized when detecting Zn[II]. Under this optimal structural setup, the spatial electric field distributions responding to variations in the refractive index of the sensing medium are also characterized. The remarkable sensitivity of the presented sensor configuration makes it a more competitive choice for deployment in further biological detection scenarios. Full article

In real-world wildfire monitoring, haze, glare, refraction artifacts, and related visual effects can cause false alarms and missed detections. This study explores two implementations: ContextFireVLM and ContextFireAgent. ContextFireVLM fine-tunes Llama-3.2 Vision with LoRA to improve the base model’s ability to identify and analyze wildfires; ContextFireAgent equips an agent with YOLO as a tool to improve the same capabilities. The first and second assessors independently inspect the full image, and the second assessor invokes YOLO only when it reports uncertainty; when their judgments agree, the final reviewer preserves the agreed decision. Because the two implementations use different models, inputs, and training pipelines, these results do not establish a causal comparison or general superiority between LoRA adaptation and the agent design. Full article

To compare oculomotor profiles among children wearing orthokeratology, defocus spectacle, and diffusion optics technology lenses in a routine pediatric myopia management setting. This real-world observational study included children who had worn one of the three lens types for approximately one year and had available eye tracking data. Lens type was selected during routine clinical care rather than assigned by the investigators. Oculomotor parameters were compared among lens groups using Kruskal–Wallis tests with false discovery rate correction. One-year spherical equivalent change was examined only in the defocus spectacle and diffusion optics technology groups. Adjusted and exploratory analyses included age, sex, baseline spherical equivalent, baseline axial length, axial elongation, and parental education categories. A total of 134 children were analyzed, including 46 in the orthokeratology group, 49 in the defocus spectacle group, and 39 in the diffusion optics technology group. Significant group differences were observed for microsaccade frequency (FDR adjusted p = 0.00099), peak velocity (FDR adjusted p = 0.00099), latency (FDR adjusted p = 0.00395), fixation disparity (FDR adjusted p = 0.00395), and conjugacy (FDR adjusted p = 0.0274). Saccade frequency and saccade amplitude did not differ significantly. One-year spherical equivalent change did not differ significantly between the defocus spectacle group and the diffusion optics technology group (−0.27 ± 0.43 D vs. −0.34 ± 0.36 D, p = 0.312). No statistically significant correlation was observed between spherical equivalent change and microsaccade frequency in the two spectacle lens groups (Spearman r = −0.231, p = 0.069). Parental education categories showed no consistent association with oculomotor parameters after correction for multiple comparisons. Children wearing different myopia control lenses showed selective differences in oculomotor profiles. Refractive change in the two spectacle lens groups was similar, and the observed oculomotor differences should not be interpreted as direct indicators of myopia control efficacy. Eye tracking may provide complementary information about visual behavior and lens adaptation, but prospective studies with age-balanced designs and longitudinal refractive and axial length outcomes are needed. Full article

Background: Epithelial ingrowth is an uncommon but potentially vision-threatening complication after keratorefractive lenticule extraction (KLEx). Although this complication is well described after flap-based refractive surgery, its occurrence after flapless lenticule extraction remains rare and is mainly reported in isolated cases. This narrative review summarizes the available literature on epithelial ingrowth after KLEx, with particular attention to proposed mechanisms, clinical presentation, imaging findings, and surgical management. An illustrative case of severe epithelial ingrowth managed with crocodile-forceps extraction is also presented. Methods: A literature search was performed to identify published reports describing epithelial ingrowth after SMILE/KLEx. Relevant articles were reviewed and compared with regard to onset, suspected mechanism, clinical severity, treatment strategy, anatomical outcome, visual recovery, and recurrence. Results: The affected eye developed extensive epithelial ingrowth associated with a postoperative tunnel laceration and marked visual deterioration during the first postoperative week. Surgical clearance through the original incision was performed using crocodile forceps followed by copious interface irrigation. Approximately one hour after treatment, AS-OCT demonstrated complete clearance of the hyperreflective interface material, corneal topography showed marked regularization, and wavefront aberrometry demonstrated a reduction in overall OPD RMS from 1.21 to 0.58 µm and higher-order RMS from 1.03 to 0.37 µm at a 4 mm pupil. Visual acuity subsequently improved over the following postoperative days, with no recurrence during 6-month follow-up. Conclusions: Severe epithelial ingrowth after KLEx may require prompt surgical intervention when rapid progression and visual deterioration occur. In this case, crocodile-forceps-assisted interface clearance through the original incision was feasible and was associated with rapid anatomical and optical recovery without cap-to-flap conversion or chemical adjuvants. Further cases are required to determine the reproducibility, safety, and long-term outcomes of this approach. Full article

Purpose: To compare the clinical and functional outcomes of two successive generations of a trifocal intraocular lens (IOL), the original Liberty 677MY and the optimized Liberty 677CMY. To the best of our knowledge, this is the first head-to-head comparison between two successive generations of any IOL model reported. Methods: This retrospective study included 42 patients (84 eyes) who underwent bilateral phacoemulsification with implantation of either the Liberty 677MY (26 eyes) or the Liberty 677CMY (58 eyes). The primary outcome was postoperative binocular intermediate visual acuity (VA). Secondary outcomes included monocular intermediate VA, monocular and binocular distance and near VA, the proportion of patients or eyes achieving ≤0.1 LogMAR, and defocus curves. Exploratory outcomes included spectacle independence, patient-reported satisfaction (Quality of vision—QoV- and Catquest-9SF), photic phenomena, and intraoperative or postoperative complications. Results: At 3 months, binocular UIVA differed by approximately 0.10 LogMAR in favor of the 677CMY cohort, which was considered clinically significant, although the difference did not reach statistical significance (p = 0.052). Supporting this tendency, monocular UIVA was significantly better with the 677CMY IOL (p = 0.012). Also, a significantly higher percentage of patients and eyes achieved binocular and monocular UIVA ≤ 0.1 LogMAR with the 677CMY IOL (p = 0.025). Defocus curves additionally showed significant between-group differences at intermediate defocus levels (−1.00 and −1.50 D; p < 0.05), favoring the 677CMY cohort. No between-group differences were observed for any distance VA parameter. Binocular near VA and near-vision thresholds were also comparable between groups, although a greater proportion of eyes achieved monocular UNVA ≤ 0.1 LogMAR with the 677CMY IOL (p = 0.016). Spectacle use, overall satisfaction, photic phenomena profile, and postoperative complications were comparable between groups. Conclusions: The optimized Liberty 677CMY exhibited a favorable pattern of intermediate visual performance compared with the 677MY while maintaining comparable distance and near VA and a similar safety profile. These findings suggest potential clinical benefits of the design modifications, although larger prospective studies are warranted to confirm these observations. Full article

Surface plasmon resonance (SPR) sensors translate refractive-index (RI) changes near an interface into measurable angular shifts, but a large shift is useful only when the resonance remains sufficiently narrow and deep. Conventional single-metal SPR structures typically force a trade-off in which sensitivity gains come at the cost of broader resonances or shallower reflectance dips. Here, a BAK1/Cu/Al/BaTiO₃/FASnI₃/BP multilayer SPR refractive-index sensor is proposed and optimized using the transfer matrix method (TMM) coupled with a genetic algorithm (GA). The Cu/Al bimetallic region provides a plasmonic metal core, BaTiO₃ and FASnI₃ progressively enhance the evanescent field, and black phosphorus (BP) forms the analyte-facing sensing interface. To avoid sensitivity-only optimization, the GA uses a composite sensitivity figure (CSF) that integrates angular sensitivity, resonance dip depth, and full width at half maximum as the fitness function. At an analyte refractive index (RI) of 1.355, the sensor reaches a maximum sensitivity of 510.11°/RIU and a CSF of 76.39 RIU⁻¹. These results establish the GA-CSF framework as a generalizable route to the balanced design of multilayer SPR refractive-index sensors and provide a computationally guided starting point for experimental implementation. Full article

Graph theory has become a fundamental mathematical framework with broad applications across various scientific fields, such as biology, network security, computer science, and chemistry. A specialized branch known as chemical graph theory employs graph-based mathematical principles to model and analyze molecular architectures. Typically, molecular graphs are generated from 2D representations of chemical structures, where physicochemical properties play a decisive role in interpreting a molecule’s physical and chemical behavior. Structural symmetry within these molecular graphs significantly aids in deriving fundamental graph parameters. Recently, a novel theoretical method has been introduced to perform a comparative analysis of seven significant domination parameters alongside the p-electronic energy of benzenoid hydrocarbons. In the field of graph theory, the independence, covering, and domination numbers stand as fundamental parameters. Inspired by this methodology and related research, this study presents an exploratory investigation into the physicochemical properties of 10 selected drug and bioactive molecules from diverse therapeutic classes to evaluate bulk size-dependent properties using these fundamental graph parameters. Various regression models were evaluated alongside leave one out cross validation (LOOCV) diagnostics for six specific properties of these compounds: boiling point (BP), enthalpy of vaporization (EV), flash point (FP), molar refractivity (MR), polarizability (P), and molar volume (MV). The results highlight the potential of these fundamental graph parameters in QSPR modeling, establishing an exploratory proof of concept that warrants future support from more comprehensive independent datasets. Full article