Double-C loop platform in combination with hydrophobic and hydrophilic acrylic intraocular lens materials.

PURPOSE: To analyze the behavior of a new double-C-loop quadripod symmetrical intraocular lens (IOL) platform combined with a hydrophilic lens material and a new hydrophobic glistening-free acrylic lens material, Ankoris and Podeye, respectively, in silico (computer simulation), in vitro (laboratory investigation), and in vivo (rabbit model). SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA, and Physiol S.A., Liege, Belgium. DESIGN: Experimental study. METHODS: An in silico simulation investigation was performed using finite elements software, an in vitro investigation according to the International Organization for Standardization (ISO11979-3:2012), and an in vivo implantation in a rabbit model with 4 weeks of follow-up. Postmortem data were collected by Miyake-Apple gross examination and histopathologic analyses. Biocompatibility and IOL centration were tested. RESULTS: Both IOLs demonstrated statistically insignificant variations in posterior and anterior capsule opacification and Soemmerring ring formation. They were well biotolerated with no signs of toxicity, inflammation, or neovascularization. Axial and centration stability were noted in vitro and in vivo as a result of significant contact between surrounding tissues and haptics and the posterior portion of the optic. CONCLUSION: The results suggest suitability of the double-C loop IOL platform for the manufacturing of premium (ie, multifocal, toric, and multifocal toric) IOLs. FINANCIAL DISCLOSURE: Drs. Bozukova, Gobin, and Pagnoulle are employees of Physiol S.A., Liege, Belgium. Dr. Pagnoulle has a proprietary interest in the tested intraocular lenses. No other author has a financial or proprietary interest in any material or method mentioned.

Evaluation of a class of polyurethane materials for intraocular lens manufacturing.

Ophthalmic lenses are medical devices with considerable requirements in terms of optical, biomechanical and biological performance. There is limited number of materials used for their manufacturing, comprising mainly silicones and poly(meth)acrylates. This series of publications aims at investigating the applicability of thermoplastic polyurethane elastomers (TPU) for the manufacturing of ophthalmic lenses and examining the properties of the respective devices. This study is related to the synthesis of TPUs with chemical compositions that comprise chemically grafted filters for the hazardous-light. GC-MS, attenuated total reflectance Fourier transform infrared spectroscopy, and UV-vis spectroscopies confirmed the reaction completion and the beneficial effect of the filters on the light transmittance, respectively. Relatively high refractive index of the material was measured and allows for the manufacturing of thinner lenses. The contrast sensitivity determined for a model intraocular lens (IOL) was satisfactory. Few optical defects were, however, present on the model lens prepared by thermoplastic injection molding. The elasticity of the materials was evaluated in view to their potential applicability as foldable IOLs by determining their glass transition temperature and their Young modulus and measuring their shore A. The TPU materials demonstrated more bioadhesive character compared with a benchmark hydrophilic acrylic reference material, which is already used for IOL manufacturing.

RGD surface functionalization of the hydrophilic acrylic intraocular lens material to control posterior capsular opacification.

Posterior Capsular Opacification (PCO) is the capsule fibrosis developed on implanted IntraOcular Lens (IOL) by the de-differentiation of Lens Epithelial Cells (LECs) undergoing Epithelial Mesenchymal Transition (EMT). Literature has shown that the incidence of PCO is multifactorial including the patient's age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs have shown that the former has more severe PCO. On the other hand, we have previously demonstrated that the adhesion of LECs is favored on hydrophobic compared to hydrophilic materials. By combining these two facts and contemporary knowledge in PCO development via the EMT pathway, we propose a biomimetically inspired strategy to promote LEC adhesion without de-differentiation to reduce the risk of PCO development. By surface grafting of a cell adhesion molecule (RGD peptide) onto the conventional hydrophilic acrylic IOL material, the surface-functionalized IOL can be used to reconstitute a capsule-LEC-IOL sandwich structure, which has been considered to prevent PCO formation in literature. Our results show that the innovative biomaterial improves LEC adhesion, while also exhibiting similar optical (light transmittance, optical bench) and mechanical (haptic compression force, IOL injection force) properties compared to the starting material. In addition, compared to the hydrophobic IOL material, our bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression, which is the crucial pathway to induce PCO. The in vitro assays suggest that this biomaterial has the potential to reduce the risk factor of PCO development.

Biointerface multiparametric study of intraocular lens acrylic materials.

PURPOSE: To compare hydrophilic and hydrophobic acrylic materials designed for intraocular lenses in a multiparametric investigation in a liquid environment to highlight their properties in terms of adhesion forces, lens epithelial cell (LEC) adhesion, and tissue response as indicators of the risk for posterior capsule opacification (PCO) development. SETTING: University of Liège, Liège, Belgium. DESIGN: Experimental study. METHODS: The hydrophobicity and surface adhesion force were assessed using contact-angle and atomic force microscopy measurements. The bioadhesiveness of the disks and the tissue response were determined by in vitro experiments using bovine serum albumin and porcine LECs and by in vivo rabbit subcutaneous implantation, respectively. RESULTS: Increasing surface hydrophobicity led to a greater surface-adhesion force and greater LEC adhesion. After 1 month, the rabbit subcutaneous implants showed a similar thin layer of fibrous capsule surrounding the disks without extensive inflammation. A layer of rounded cells in contact with disks was detected on the hydrophobic samples only. CONCLUSIONS: Hydrophobic acrylic disks that have been associated with a reduced risk for PCO in clinical studies showed increased tackiness. FINANCIAL DISCLOSURES: Proprietary or commercial disclosures are listed after the references.

Biomechanical and optical properties of 2 new hydrophobic platforms for intraocular lenses.

PURPOSE: To compare the biomechanical and optical properties of 2 new hydrophobic platforms and a series of commercially available foldable intraocular lenses (IOLs). SETTING: Center for Education and Research on Macromolecules, University of Liège, Liège, Belgium. DESIGN: Experimental study. METHODS: Eleven benchmark foldable IOLs (iPure, Podeye, Acrysof SN60WF, Envista MX60, Sensar AR40e, Tecnis ZCB00, Isert 251, AF-1 YA-60BB, Finevision, Acri.Tec 366D, and Ioflex) were tested by standard analytical methods for biomechanical, rheological, and optical investigations under identical conditions. RESULTS: With 1 exception, IOLs equilibrated in aqueous medium had a lower glass-transition temperature, higher deformability, lower injection forces, and complete recovery of their initial optical properties after injection. Typical hydrophobic acrylic dry-packaged IOLs required higher injection forces with high residual deformation and lost part of their initial optical quality after injection. Hydrophobic acrylic C-loop, double C-loop, and closed quadripod haptics applied optimum compression forces to the capsular bag with negligible optic axial displacement and tilt compared with plate haptics and poly(methyl methacrylate) haptics. CONCLUSIONS: The combination of the C-loop haptic and the bioadhesive glistening-free material, which absorbs a predetermined amount of water, allowed for a biomechanically stable IOL. The same material used in association with a double C-loop haptic design facilitated the perioperative manipulation and placement of the IOL in a smaller capsular bag without impairing the other biomechanical properties of a single C-loop design.

Assessment of new-generation glistening-free hydrophobic acrylic intraocular lens material.

PURPOSE: To determine the hydrophobic, antiglistening, and bioadhesiveness properties of a new polymer, GF raw material, and to determine the suitability of this material for use in intraocular lenses (IOLs). SETTING: University of Liege, Liege, Belgium. DESIGN: Experimental study. METHODS: Intraocular lenses made of the new hydrophobic acrylic material were tested and compared with reference acrylic materials. The stability of their polymer matrix was estimated by testing for glistenings. The relative surface hydrophobicity was quantified via contact-angle measurements. The degrees of bioadhesiveness of the reference and test materials were assessed by in vitro porcine lens epithelial cell (LEC) culture. RESULTS: The glistening test showed that the new material had greater stability under worst-case conditions than previous-generation hydrophobic acrylic materials. The new polymer had the same hydrophobic properties as the hydrophobic Acrysof IQ SN60WF material; both materials were less hydrophobic than the hydrophobic Sensar AR40e material and more hydrophobic than the hydrophilic Ioflex IOL material. The in vitro bioadhesiveness tests showed that porcine LEC adhesion levels of the new material were intermediate with respect to those of the 2 reference hydrophobic materials. CONCLUSIONS: When equilibrated in aqueous medium, the new-generation hydrophobic acrylic material reached a low water content at equilibrium, making it glistening free. The hydrophobicity and bioadhesiveness of the new raw material were comparable to those of state-of-the-art reference materials; these properties may resist the formation of posterior capsule opacification. FINANCIAL DISCLOSURE: Dr. Pagnoulle has a proprietary interest in the GF material. Drs. Pagnoulle, Gobin, and Bozukova are employees of Physiol S.A. Mme. V. Bertrand and Dr. Gillet-De Pauw have no financial or proprietary interest in any material or method mentioned.

Design and qualification of a diffractive trifocal optical profile for intraocular lenses.

PURPOSE: To theoretically and experimentally assess a new aspheric diffractive trifocal intraocular lens (IOL). SETTING: Centre Spatial de Liège, Liège, Belgium. DESIGN: Evaluation of diagnostic test or technology. METHODS: The theoretical profile of the IOL was designed using software simulation and validated by optical calculation software tools that enabled complete theoretical characterization. These data resulted in a new aspheric diffractive trifocal IOL. The IOL theoretically allows improved intermediate vision without impairing near and far vision and favors distance vision in mesopic conditions without increasing halos or glare perception under dim light or large pupil conditions. The theoretical findings were compared with those of in vitro testing on the optical bench. RESULTS: There was good agreement between the theoretical profile and achieved IOL profile. The simulated and achieved light distribution and focus distribution showed good concordance. The FineVision aspheric trifocal IOL provided intermediate addition at 1.75 diopters. CONCLUSION: The combination of 2 diffractive profiles to achieve far, intermediate, and near correction is validated. Further clinical investigations are required to validate these principles. FINANCIAL DISCLOSURE: Dr. Houbrechts has no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Hydrogel nanocomposites: a potential UV/blue light filtering material for ophthalmic lenses.

Poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (poly(HEMA-co-MMA)) and ZnS hydrogel nanocomposites were prepared and characterized. The chemical composition of the inorganic nanoparticles was confirmed by X-ray diffraction, and the homogeneity of their distribution within the hydrogel was assessed by transmission electron microscopy. The influence of the content of ZnS nanoparticles on the optical performances of the nanocomposites was investigated by UV-Vis spectroscopy. The ability of the hydrogel nanocomposites to filter the hazardous UV light and part of the blue light was reported, which makes them valuable candidates for ophthalmic lens application. In contrast to the optical properties, the thermo-mechanical properties of neat poly(HEMA-co-MMA) hydrogels were found to be largely independent of filling by ZnS nanoparticles (≤2 mg/ml co-monomer mixture). Finally, in vitro cell adhesion test with lens epithelial cells (LECs), extracted from porcine lens crystalline capsule, showed that ZnS had no deleterious effect on the biocompatibility of neat hydrogels, at least at low content.

Imparting antifouling properties of poly(2-hydroxyethyl methacrylate) hydrogels by grafting poly(oligoethylene glycol methyl ether acrylate).

The antifouling properties of poly(2-hydroxyethyl methacrylate- co-methyl methacrylate) hydrogels were improved by the surface grafting of a brush of poly(oligoethylene glycol methyl ether acrylate) [poly(OEGA)]. The atom-transfer radical polymerization (ATRP) of OEGA (degree of polymerization = 8) was initiated from the preactivated surface of the hydrogel under mild conditions, thus in water at 25 degrees C. The catalytic system was optimized on the basis of two ligands [1,1,4,7,10,10-hexamethyl-triethylenetetramine (HMTETA) or tris[2-(dimethylamino)ethyl]amine (Me6TREN)] and two copper salts (CuIBr or CuICl). Faster polymerization was observed for the Me 6TREN/CuIBr combination. The chemical composition and morphology of the coated surface were analyzed by X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements by the water droplet and captive bubble methods, scanning electron microscopy, and environmental scanning electron microscopy. The hydrophilicity of the surface increased with the molar mass of the grafted poly(OEGA) chains, and the surface modifications were reported in parallel. The antifouling properties of the coatings were tested by in vitro protein adsorption and cell adhesion tests, with green fluorescent protein, beta-lactamase, and lens epithelial cells, as model proteins and model cells, respectively. The grafted poly(OEGA) brush decreased the nonspecific protein adsorption and imparted high cell repellency to the hydrogel surface.

Improved performances of intraocular lenses by poly(ethylene glycol) chemical coatings.

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of protein adsorption and lens epithelial cell (LEC) adhesion, growth, and proliferation, is the secondary cataract, referred to as posterior capsular opacification (PCO). To avoid PCO formation, a poly(ethylene glycol) (PEG) chemical coating was created on the surface of hydrogel IOLs. Attenuated total reflectance Fourier transform infrared spectroscopy, "captive bubble" and "water droplet" contact angle measurements, and atomic force microscopy analyses proved the covalent grafting of the PEG chains on the IOL surface while keeping unchanged the optical properties of the initial material. A strong decrease of protein adsorption and cell adhesion depending on the molar mass of the grafted PEG (1100, 2000, and 5000 g/mol) was observed by performing the relevant in vitro tests with green fluorescent protein and LECs, respectively. Thus, the study provides a facile method for developing materials with nonfouling properties, particularly IOLs.

Polyolefin matrixes with permanent antibacterial activity: preparation, antibacterial activity, and action mode of the active species.

Poly[2-(tert-butylamino)ethyl methacrylate] (PTBAEMA) belongs to a novel class of water-insoluble biocides. Dispersion of a poly(ethylene-co-butylene)-b-poly[2-(tert-butylamino)ethyl methacrylate] diblock copolymer (PEB-b-PTBAEMA) within low-density polyethylene (LDPE) imparts antimicrobial properties to the polyolefin as assessed by the viable cell counting method against Escherichia coli (E. coli). This diblock copolymer has been synthesized by atom transfer radical polymerization (ATRP) with a poly(ethylene-co-butylene) (PEB) oligomer end-capped by an activated bromide as a macroinitiator for the polymerization of 2-(tert-butylamino)ethyl methacrylate (TBAEMA). Morphological changes of E. coli bacteria in contact with modified LDPE have been observed by transmission and scanning electron microscopy and indicate that the diblock copolymer is bactericide rather than bacteriostatic. Finally, the action mode of the PEB-b-PTBAEMA copolymer more likely relies on the displacement of the Ca(2+) and/or Mg(2+) ions of the outer membrane of the bacteria, which is disorganized and finally disrupted.

Noncovalent functionalization of multi-walled carbon nanotubes by pyrene containing polymers.

Multi-walled carbon nanotubes (MWNTs) have been solubilized in water and in various organic solvents by noncovalent side-wall functionalization by pyrene containing polymers.