Mechanically Enhanced Soft Contact Lenses from Photodimerization Cross-Linking. ACS omega In this study, we synthesized three novel acrylic monomers with a cinnamate group. We then mixed each monomer with 2-hydroxyethyl methacrylate (HEMA) to prepare soft contact lenses through bulk polymerization. Fourier transform infrared (FT-IR) and UV spectral analyses confirmed that the cinnamate group in the polymer undergoes a photodimerization reaction via UV irradiation. After UV curing, the present lenses stably maintained their shapes even in a water-swollen state and showed significantly improved mechanical properties compared to conventional lenses manufactured using a cross-linking agent. These lenses showed slightly lower water contact angles than the conventional lenses, although the water content was slightly reduced. The present photodimerization cross-linking method was found to be useful in reducing the tearability of soft lenses. 10.1021/acsomega.3c04489

Gelatine-based drug-eluting bandage contact lenses: Effect of PEGDA concentration and manufacturing technique. Zidan Ghada,Greene Carol A,Etxabide Alaitz,Rupenthal Ilva D,Seyfoddin Ali International journal of pharmaceutics Drug-eluting bandage contact lenses (BCLs) have been widely studied as an alternative to eye drops due to their ability to increase the drug residence time and bioavailability as well as improve patient compliance. While silicone hydrogel polymers are commonly used in drug-eluting BCLs due to their transparency, mechanical properties and high oxygen permeability, gelatine hydrogels are also clear, flexible and have high oxygen permeability and may therefore be suitable contact lens materials. Moreover, the rheological properties of gelatine hydrogels allow their use as inks in extrusion-based 3D printers, therefore opening the door to a wide range of applications. Drug-loaded gelatine methacryloyl (GelMA) BCLs with different concentrations of poly (ethylene glycol) diacrylate (PEGDA) were prepared using solvent casting and 3D printing. The prepared lenses were characterised for their swelling ratio, in vitro degradation, and drug release properties. The results showed that the incorporation of 10% PEGDA improved the lenses' resistance to handling and protected them during degradation testing, reduced the swelling ratio and prolonged the release of dexamethasone (DEX). Both techniques were deemed suitable to use in the manufacturing of drug-eluting BCLs noting that the optimal formulation may vary according to the preparation technique utilised. 10.1016/j.ijpharm.2021.120452

In vitro and in vivo evaluation of brimonidine loaded silica nanoparticles-laden silicone contact lenses to manage glaucoma. Journal of biomaterials applications Glaucoma is treated by frequent instillation of 0.2% w/v brimonidine tartrate eye drop solution, which showed poor ocular bioavailability of 1-3%. Medicated contact lenses can be used to improve the ocular drug bioavailability. However, drug loading in the contact lens matrix showed high burst release and changes the optophysical properties of the contact lens material. In this paper, a novel brimonidine loaded silica nanoparticles-laden silicone contact lenses (Bri-Si) were designed to achieve controlled drug delivery without altering the optophysical properties of the contact lens. Silica nanoparticles were prepared by polymerizing octadecyltrimethoxysilane (OTMS) molecules at the oil/water interface of microemulsion. Traditional soaking method (Bri-SM), direct brimonidine-loading method (Bri-DL) and microemulsion-laden contact lens (Bri-ME) were developed for comparison. The Bri-Si lens showed improved swelling, transmittance, oxygen permeability and lysozyme adherence compared to Bri-SM, Bri-DL and Bri-ME lenses. The Bri-DL lens showed high brimonidine leaching during extraction and sterilization steps, with low cumulative drug release. While, Bri-Si lens show controlled brimonidine release for 144 h. In a rabbit tear fluid model, the Bri-Si lens showed high brimonidine concentration for 96 h compared to Bri-ME lens and eye drop therapy. Based on histopathological studies of cornea, the Bri-Si lens was found to be safe for human applications. The data demonstrated the novel application of silica nanoparticles to control brimonidine release from the contact lens without altering the optophysical properties of the contact lens. 10.1177/08853282221090880

The influence of structure and morphology on ion permeation in commercial silicone hydrogel contact lenses. Saez-Martinez Virginia,Mann Aisling,Lydon Fiona,Molock Frank,Layton Siân A,Toolan Daniel T W,Howse Jonathan R,Topham Paul D,Tighe Brian J Journal of biomedical materials research. Part B, Applied biomaterials The importance of the microstzructure of silicone hydrogels is widely appreciated but is poorly understood and minimally investigated. To ensure comfort and eye health, these materials must simultaneously exhibit both high oxygen and high water permeability. In contrast with most conventional hydrogels, the water content and water structuring within silicone hydrogels cannot be solely used to predict permeability. The materials achieve these opposing requirements based on a composite of nanoscale domains of oxygen-permeable (silicone) and water-permeable hydrophilic components. This study correlated characteristic ion permeation coefficients of a selection of commercially available silicone hydrogel contact lenses with their morphological structure and chemical composition. Differential scanning calorimetry measured the water structuring properties through subdivision of the freezing water component into polymer-associated water (loosely bound to the polymer matrix) and ice-like water (unimpeded with a melting point close to that of pure water). Small-angle x-ray scattering, and environmental scanning electron microscopy techniques were used to investigate the structural morphology of the materials over a range of length scales. Significant, and previously unrecognized, differences in morphology between individual materials at nanometer length scales were determined; this will aid the design and performance of the next generation of ocular biomaterials, capable of maintaining ocular homeostasis. 10.1002/jbm.b.34689

Central-to-peripheral corneal edema during wear of embedded-component contact lenses. Kim Young Hyun,Lin Meng C,Radke Clayton J Contact lens & anterior eye : the journal of the British Contact Lens Association PURPOSE:With active investigation underway for embedded-circuit contact lenses, safe oxygen supply of these novel lenses remains a question. Central-to-peripheral corneal edema for healthy eyes during wear of soft contact (SCL) and scleral lenses (SL) with embedding components is assessed. METHODS:Various 2-dimensional (2D) designs of SL and SCL with embedded components are constructed on Comsol Multiphysics 5.5. Local corneal swelling associated with the designed lenses is determined by a recently developed 2D metabolic-swelling model. Settled central post-lens tear-film thicknesses (PoLTFs) are set at 400 μm and 3 μm for SL and SCL designs, respectively. Each lens design has an axisymmetric central and an axisymmetric peripheral embedment. Oxygen permeability (Dk) of the lens and the embedments ranges from 0 to 200 Barrer. Dimensions and location of the embedments are varied to assess optimal-design configurations to minimize central-to-peripheral corneal edema. RESULTS:By adjusting oxygen Dk of the central embedment, the peripheral embedment, or the lens matrix polymer, corneal swelling is reduced by up to 2.5 %, 1.5 %, or 1.4 % of the baseline corneal thickness, respectively, while keeping all other parameters constant. A decrease in PoLTF thickness from 400 μm to 3 μm decreases corneal edema by up to 1.8 % of the baseline corneal thickness. Shifting the peripheral embedment farther out towards the periphery and towards the anterior lens surface reduces peak edema by up to 1.3 % and 0.6 % of the baseline corneal thickness, respectively. CONCLUSIONS:To minimize central-to-peripheral corneal edema, embedments should be placed anteriorly and far into the periphery to allow maximal limbal metabolic support and oxygen transport in the polar direction (i.e., the θ-direction in spherical coordinates). High-oxygen transmissibility for all components and thinner PoLTF thickness are recommended to minimize corneal edema. Depending on design specifications, less than 1 % swelling over the entire cornea is achievable even with oxygen-impermeable embedments. 10.1016/j.clae.2021.101443