Search Results (134)

Continuous intraocular pressure (IOP) monitoring is crucial for glaucoma management. Currently, traditional static IOP measurements often fail to detect circadian fluctuations, leading to a clinical dilemma where “normal IOP” is observed despite persistent visual field deterioration. This study presents a wireless, passive localized surface plasmon resonance (LSPR) sensing platform integrated into flexible silicone hydrogel contact lenses. Gold nanoparticles (AuNPs), synthesized via the sodium citrate reduction method, were incorporated into the lens periphery using a “swelling-induced nano-doping” technique to transduce IOP-induced corneal strain into detectable spectral shifts. Ex vivo porcine eye investigations established a physical mapping model, confirming significant LSPR peak wavelength response trends in correlation with IOP variations (10–50 mmHg) and corneal curvature changes. Subsequent 21-day in vivo rabbit studies demonstrated excellent ocular surface biocompatibility; quantitative histopathological analysis (HE, PAS, and Ki67 staining) revealed no significant adverse alterations in corneal endothelial cell density or conjunctival goblet cell function compared to control groups (p > 0.05). Furthermore, the platform maintained high structural integrity and anterior segment tolerance under transient high-IOP conditions. While currently a proof-of-concept, these results indicate that the LSPR-active hybrid system effectively captures dynamic IOP fluctuation patterns as an optical response to acute interventions, providing a foundational engineering path for next-generation, battery-free wearable diagnostics in personalized glaucoma care without the need for built-in electronics. Full article

Ultrasound coupling technology is pivotal to ensuring high-quality diagnostic imaging, yet conventional water-based gels face persistent challenges, including acoustic impedance mismatch, air-bubble formation, dehydration, messiness, and cross-contamination risks. This review presents a comprehensive analysis of the evolution, materials science, and clinical performance of ultrasound gel pads, an advanced alternative engineered for superior acoustic transmission, hygiene, and patient comfort. Historical progression from early coupling agents to modern polymeric and hydrogel-based pads is traced, highlighting breakthroughs such as bilayer hydrogels, nanocomposite reinforcements, metamaterial-inspired designs, and patient-specific 3D-printed pads. Comparative evaluations demonstrate that gel pads, particularly those integrating nanotechnology, rival but often outperform traditional gels in transmission efficiency, near-field resolution, and adaptability to complex anatomical surfaces, while offering reusability and reduced environmental impact. For instance, solid gel pads achieved 92.3% stone disintegration, compared with 45.5% for semi-liquid gel, in ESWL phantom studies (p < 0.001). Materials, including polyacrylamide, silicone, and advanced hydrogels, are analyzed for mechanical properties, biocompatibility, and sustainability, with emphasis on biodegradable and locally sourced alternatives. Manufacturing innovations ranging from continuous casting to additive manufacturing enable customization, functional integration, and scalable production, although cost, supply chain stability, and regulatory compliance remain critical barriers. By uniting advances in materials engineering, nanotechnology, and precision manufacturing, ultrasound gel pads have demonstrated strong potential to advance coupling media for diagnostic, therapeutic, and wearable ultrasound applications, enabling higher diagnostic accuracy, streamlined workflows, and patient-centered care across diverse clinical and resource-limited settings. Full article

The non-albicans Candida species Candida tropicalis is an opportunistic fungal pathogen that forms a robust gel-like biofilm on polymeric prosthetic materials. These biofilms are embedded in an extracellular polymeric substance that retains large amounts of water, resulting in a hydrogel-like matrix that protects fungal cells, increases antifungal resistance, and contributes to the biofouling of these prosthetic materials. Biofouling is the unwanted colonization and accumulation of microbial communities on material surfaces, which alters their function and compromises clinical performance. Clinically, it is significant because it is linked to recurrent urinary tract infections, bloodstream infections, and persistent device-related infections, which often result in therapeutic failure and device malfunction. Polymers such as silicone elastomer, polypropylene, polystyrene, polyurethane, polyethylene, and polyvinyl chloride are widely used in catheters, surgical meshes, implants, and prostheses because of their durability, flexibility, and biocompatibility, yet their surface properties often encourage microbial adhesion and biofilm formation. This review emphasizes that the gel-like biofilm architecture of C. tropicalis underpins its persistence and resistance, while also highlighting promising antifungal strategies being developed to mitigate these infections. Notably, palmitic acid has been shown to disrupt mature biofilms by lowering ergosterol and inducing oxidative stress, whereas C-10 massoia lactone damages the extracellular matrix and suppresses hyphal growth. Drug repurposing approaches, such as combining minocycline with fluconazole, restore susceptibility in resistant isolates and demonstrate synergistic antibiofilm activity. Additionally, biomaterial-based interventions, such as chitosan coatings on silicone surfaces, significantly reduce fungal adhesion and biofilm formation. Together, these findings reflect a translational shift toward integrating natural products, repurposed drugs, and functionalized biomaterials into antifungal development. Understanding biofouling and these emerging strategies is crucial for developing effective control measures against C. tropicalis biofilms and for guiding the design of infection-resistant prosthetic devices. Full article

Silicone hydrogels offer high oxygen permeability but suffer from poor wettability. This study integrates a TRISS-based system (0–2.0 wt%) with a fixed PVP/NVP matrix (1.0/0.5 wt%) to enhance hydration-induced dimensional stability and surface properties. Fabricated via cast-molding, the lenses demonstrated that TRISS incorporation significantly enhances oxygen transport. Specifically, the 2.0 wt% TRISS formulation (S2.0) achieved an ~1.9-fold increase in oxygen-induced current (from 0.97 μA in pure-HEMA to 1.86 μA) while strongly suppressing hydration-induced swelling. To counter TRISS’s inherent hydrophobicity, the PVP/NVP matrix acted as a vital compensatory mechanism, driving the equilibrium contact angle down to 56.04° and avoiding the severe hydrophobic plateau (93.79°) of the additive-free comparator. S2.0 maintained a robust oxygen response alongside improved wettability. In conclusion, this system defines a workable low-silicone design window accommodating up to 2.0 wt% TRISS without wettability loss or optical degradation (>97%). Crucially, by leveraging TRISS to mitigate swelling-induced mechanical stress and PVP/NVP to ensure stable wettability, this structurally robust hydrogel provides a highly viable foundational matrix for future smart contact lenses equipped with diagnostic micro-components. Full article

The occurrence of contact lens complications caused by inadequate cleaning of the lenses using “All-in-One” contact lens cleaning solutions (CLCSs) represents a medically relevant problem worldwide. This study explores the potential of cold atmospheric plasma (CAP) to enhance the efficacy of CLCSs and address complications from inadequate lens hygiene. It was examined whether exposure to CAP for 1–24 h could boost the antibacterial effects of CLCSs and other solutions, including Milli-Q water (M-QW), physiological saline (NaCl), and Dulbecco’s Phosphate Buffered Saline (DPBS). Additionally, the stability of reactive oxygen and nitrogen species (RONS) and their impact on pH immediately after treatment and over 1–4 weeks was assessed. Furthermore, the cleaning efficacy of plasma-activated solutions (PASs) was tested on lipid-coated silicone hydrogel lenses. Results showed that CAP increased RONS concentrations immediately, with elevated levels persisting over time. While no significant improved antibacterial effect was observed against Escherichia coli in CLCSs, CAP treatment generated disinfectant properties in M-QW and NaCl solutions. Importantly, CAP-treated CLCSs significantly improved the cleaning performance on lipid-coated lenses, though M-QW’s cleaning ability worsened post-treatment. pH measurements indicated notable decreases in M-QW and NaCl after CAP, whereas buffered solutions like CLCSs and DPBS remained stable. Overall, CAP demonstrates promise for contact lens disinfection and surface modification; however, further research and pre-clinical trials are necessary before clinical application in ophthalmology. Full article

In this study, we present the synthesis and characterization of graphene oxide (GO)-based hydrogels reinforced with hydroxyapatite (HA), titanium dioxide (TiO₂), zinc oxide (ZnO), silicon oxide (SiO₂), silver (Ag), and graphitic carbon nitride (g-C₃N₄). The aim is to develop multifunctional hydrogels with enhanced structural and biological performance and photocatalytic activity, opening the way for applications in regenerative medicine. The structure and composition of the hydrogels were investigated using FTIR and UV–Vis spectroscopy, which highlighted the chemical interactions between GO and the incorporated nanoparticles. The morphology was analyzed through scanning electron microscopy (SEM) and metallographic optical microscopy (MOM), confirming a uniform distribution of the inorganic phases and an internal architecture optimized for stability and bioactivity. Antibacterial activity was evaluated against Gram-positive and Gram-negative strains, both in the absence and presence of photodynamic therapy. The latter was activated by a Woodpecker laser at a 420 nm wavelength. The results showed significant bacterial inhibition, further enhanced by laser exposure, suggesting a synergistic effect between photocatalytic activation and the hydrogel components. Overall, the obtained hydrogels demonstrate robust mechano-structural properties and promising biological activity, supporting their potential for innovative biomedical applications in the tissue regeneration field and for the emerging biofunctional technologies. Full article

Background: To compare clinical outcomes of Lotrafilcon A and Balafilcon A silicone hydrogel bandage contact lenses (BCLs) following transepithelial photorefractive keratectomy (TPRK). Methods: A randomized, double-blind, contralateral eye study enrolled 41 TPRK patients (82 eyes), with each eye randomly assigned one BCL type. Assessments included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, ocular pain and irritation, epithelial healing, limbal and conjunctival hyperemia, lens mobility, and the amount of protein deposition on the BCLs. Results: Postoperative day 1 pain score was lower in Group A (2.80 ± 2.35) than in Group B (4.44 ± 2.46, p = 0.003). Group A had significantly less protein deposition (day 3: 9.92 ± 9.82 vs. 25.75 ± 9.86 μg, p < 0.001; day 4: 9.47 ± 10.06 vs. 32.60 ± 16.71 μg, p = 0.005). No statistically significant differences were observed between the two groups in terms of corneal epithelial defect area, corneal epithelial healing time, UDVA, CDVA, limbal or conjunctival hyperemia, and lens movement. Conclusions: Lotrafilcon A outperformed Balafilcon A in reducing ocular pain, foreign body sensation, and protein deposition, suggesting that Lotrafilcon A may be a more suitable therapeutic BCL option following TPRK. Full article

This study investigates the compatibility of various acrylic and silane monomers and aims to develop a high-performance hydrogel ophthalmic polymer. The formulations incorporated 2-(trimethylsiloxy)ethyl methacrylate (2TSEMA), 3-(methacryloxy)propyl tris(trimethylsiloxy)silane (3TRIS), and (1,1-dimethyl-2-propyl)oxy-trimethylsilane (TRIS) as functional additives to a base composition of silanol-terminated silicone (Sil-OH), N,N–dimethyl acrylamide (DMA), methyl methacrylate (MMA), and methyl acrylate (MA). Copolymerization was carried out using ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent and azobisisobutyronitrile (AIBN) as the thermal initiator. All synthesized hydrogel lenses exhibited excellent optical transparency, indicating good monomer compatibility. The optical and physicochemical properties of the hydrogels varied depending on monomer composition. Notably, the formulation combining 2TSEMA with 1 wt% TRIS showed enhanced oxygen permeability, suggesting a synergistic interaction between the two silane-based components. These results demonstrate the potential of such hybrid formulations for use in next-generation functional hydrogel ophthalmic lenses. Full article

Self-healing polymer-based coatings have emerged as a new generation of adaptive protective materials capable of restoring their structure and function after damage. This review provides a comprehensive analysis of current strategies enabling autonomous or externally triggered repair in polymeric films, including encapsulation, reversible chemistry, and microvascular network formation. Emphasis is placed on polymer–inorganic hybrid composites and vitrimeric systems, which integrate barrier protection with stimuli-responsive healing and recyclability. Comparative performance across different matrices—epoxy, polyurethane, silicone, and polyimine—is discussed in relation to corrosion protection and biomedical interfaces. The review also highlights how dynamic covalent and supramolecular interactions in hydrogels enable self-repair under physiological conditions. Recent advances demonstrate that tailoring interfacial compatibility, healing kinetics, and trigger specificity can achieve repeatable, multi-cycle recovery of both mechanical integrity and functional performance. A representative selection of published patents is also shown to illustrate recent technological advancements in the field. Finally, key challenges are identified in standardizing evaluation protocols, ensuring long-term stability, and scaling sustainable manufacturing. Collectively, these developments illustrate the growing maturity of self-healing polymer coatings as multifunctional materials bridging engineering, environmental, and biomedical applications. Full article

Background/Objectives: A meta-analysis was conducted to study the in vitro release of hydrophilic therapeutics from contact lenses, loaded using the soaking method. Fifty-three experiments were studied that measure the cumulative release of therapeutics from (mostly) commercial contact lenses placed in a vial. Methods: A mathematical model and a parameter-fitting algorithm are presented to estimate the diffusion coefficient (D) and 50% therapeutic release time ($T_{50}$) of all the experimental lens–therapeutic combinations. Statistical methods were used to analyze the relationships between lens materials, therapeutic properties, and predicted parameter values (D and $T_{50}$). Results: The mathematical framework was validated against previous studies. It was found that lens water content directly and moderately influences the estimated diffusion coefficient. More specifically, the median diffusivity of silicone hydrogel (SH) contact lenses was statistically different from that of conventional hydrogel (CH) lenses. The dependencies of other lens and therapeutic properties on diffusivity were complex, with special cases studied to elicit dependencies. A predictive tool was constructed to estimate the logarithm of 50% therapeutic release time ($\log \left(T_{50}\right)$), given the lens water content and the therapeutic molecular volume and density. Conclusions: The conducted meta-analysis found that the kinetic release of therapeutics from contact lenses depends on the properties of both the contact lens and therapeutics. The statistical model explained 64% of the variability of the $\log \left(T_{50}\right)$ and can be used in the preliminary stages of contact lens drug delivery development. Full article

Most long-term mobile EEG monitoring systems require professional application of the electrodes, which makes them inconvenient for everyday use. Additionally, many materials that facilitate EEG application, such as dry electrodes, may cause discomfort when worn for longer periods of time. To address these problems, we designed flex-printed EEG electrode grids (trEEGrid) and evaluated signal quality based on two pre-applied conductive materials. Self-applicable trEEGrid patches with a conductive solid hydrogel and a novel silicone-based dry material were used in a day-long (5–6 h) recording session, which included a 4 h continuous recording of impedance levels, as well as two auditory task recordings in the morning and afternoon. The signal-to-noise ratio (SNR) of the auditory evoked potentials (AEPs), AEP morphology, and impedance levels of the conductive materials were compared to evaluate overall signal quality, and further comparisons took place between the morning and afternoon sessions to evaluate signal deterioration over time. Comparable impedance values were observed for both silicone and hydrogel materials, but the silicone material exhibited a higher outlier rate, with impedance values over 200 kΩ. Over time, the impedance values increased for the silicone material and decreased for the hydrogel material. The morphology of the AEP was reproduced comparably well with both materials, with reasonable SNRs in both the morning and the afternoon. In conclusion, when combined with flex-printed electrode grids, silicone and hydrogel materials make it feasible to collect high-quality long-term EEG signals with high wearing comfort. Full article

Ultraviolet light-emitting diode (UV LED) technology offers advantages over conventional UV mercury (UV Hg) lamps, including precise wavelength control, high energy efficiency and rapid curing. While UV LED is widely applied in sectors like dentistry, printing, and electronics, its application in contact lens manufacturing remains relatively low. This study evaluates the feasibility of integrating UV LED technology curing as a replacement for UV Hg lamps to produce silicone hydrogel contact lenses. Many manufacturers utilizing UV Hg systems encounter challenges such as extended curing times and increased cosmetic defect rates. In this study, lenses were formulated using a mixture of hydrophobic macro-monomer, silicone monomer, and hydrophilic monomer. The formulations were cured using both UV LED and UV Hg lamps systems under controlled intensities, and two curing configurations were assessed: single-sided (SC) and double-sided (DC). The UV Hg light intensity was maintained between 1.1 and 3.1 mW/cm², reflecting standard production values, while the UV LED intensity was set at 32 mW/cm² to ensure uniform light distribution in the mold. The findings showed an improved degree of conversion (DOC) for UV LED cured lenses (86–88%) compared to UV Hg (79.5–82.3%), along with increased water content (ranging between 34 and 36.8%) and ion permeability (7.1–8.3 mm²/min). The optical properties of the cured lenses remained consistent across both methods. Notably, UV LED curing reduced cosmetic defects by up to 50% and shortened curing time by 3 to 4 times. These enhancements support UV LED as a superior alternative for contact lens curing, enabling scalable, efficient, and high-quality manufacturing. Full article

Visual quality in the human eye depends on the integrity of ocular structures. Soft contact lenses interact directly with these structures and can also serve as an external source of straylight. The purpose of this study was to quantify changes in optical quality among habitual wearers of monthly disposable silicone hydrogel soft contact lenses (SCLs) by comparing retinal straylight with new versus month-old lenses. Retinal straylight was measured using a C-Quant straylight meter in 33 young adults (22.0 ± 1.4 years) wearing either comfilcon A (n = 17) or lotrafilcon B (n = 16) lenses. Measurements were first performed with month-old SCLs that had been worn for ≤4 h that day; after lens replacement and a 15 min adaptation period, measurements were repeated with new SCLs. The mean decimal logarithm of the straylight parameter, log(s), was significantly higher with month-old SCLs (0.97 ± 0.17) than with new SCLs (0.86 ± 0.15; paired t-test, p < 0.001), yielding an average increase of Δlog(s) = 0.11 ± 0.08. No significant difference was found between materials. Thirty-six percent of participants reported end-of-cycle visual discomfort. These findings indicate that monthly SCLs at the end of the replacement period can measurably increase retinal straylight. Full article

Soft contact lenses are usually characterised at room temperature, yet they function on the eye at body temperature, where their mechanics and optical performance can change. This study investigated whether soft silicone hydrogel lenses become more compliant in a physiological environment. Two silicone hydrogel materials (Definitive 74 and Unisil) were tested at 24 °C and 35 °C using uniaxial tensile and compression methods, with Ogden hyperelastic models fitted and finite element analysis performed on a realistic eye model. Both materials became more compliant at 35 °C, with Definitive 74 showing a larger modulus decrease (0.40 to 0.32 MPa) than Unisil (0.73 to 0.70 MPa). Finite element simulations indicated that these temperature-driven changes in compliance significantly affected refractive power, especially when the lens base curve exceeded the corneal radius by more than 5%. These findings demonstrate that soft silicone hydrogel lenses are indeed more compliant in a warm, hydrated environment, highlighting the need for physiologically relevant testing to inform design, fitting strategies, comfort, and vision outcomes. Full article

Objectives: This study evaluated the comfort of using silicone tubes installed in the oral cavity as a reservoir for a hydrogel that allows for a slow delivery of the active substance acting locally or systemically. Methods: Perforated silicone tubes 8 cm long with two internal diameters were used: T1 (1.5 mm) and T2 (2.4 mm). The reservoirs were filled with hydrogel placebo formulations: carbomer 1.5% (C), hydroxyethylcellulose 4% (HEC), or hydroxypropylmethylcellulose (hypromellose) 3% (HPMC). Physical parameters of the gel were determined with a viscometer and a texture analyzer. During 4 h of application, the volunteers reported sensory perceptions, and the rate of gel erosion was evaluated. The results were correlated with the viscosity, rheology, and dissolution rate of the gels measured in vitro. Results: Volunteers reported only mild discomfort wearing the device, preferring smaller-sized tubes. The tubes were easy to apply and generally comfortable, with no reports of significant discomfort. Despite similar viscosity and rheology, the polymer type had a significant impact on erosion rate, both in vitro and in vivo. After 4 h of application in vivo, more than 90% of the carbomer gel remained in the tube, while in the case of less cohesive HPMC or HEC gels, this was about 50%. A statistically significant correlation was observed between the in vitro and in vivo mean erosion percentages for the HEC and HPMC gels. Conclusions: This study supports the use of silicone tubes as effective reservoir devices for prolonging the residence time of drug formulations in the oral cavity. Full article