Hydrogel Lenses Research Articles

Contact Lenses Loaded with Melatonin Analogs: A Promising Therapeutic Tool against Dry Eye Disease.

Melatonin analogs topically administered evoke a potent tear secretagogue effect in rabbits. This route of drug administration requires high drug concentration and frequent dosing due to its reduced ocular surface retention. Therefore, contact lenses (CLs) have emerged as an alternative drug-delivery system that prolongs drug retention in the cornea, improving its therapeutic performance. This study explores the in vitro ability of five commercially available hydrogel CLs to act as a delivery system for melatonin analogs and the in vivo secretagogue effect of melatonin analog-loaded CLs. We soaked CLs with melatonin or melatonin analog solutions (1 mM) for 12 h. Spectroscopic assays showed that IIK7-loaded CLs led to the inadequate delivery of this compound. Conventional hydrogel lenses loaded with agomelatine released more agomelatine than silicone ones (16–33% more). In contrast, the CLs of silicone materials are more effective as a delivery system of 5-MCA-NAT than CLs of conventional materials (24–29%). The adaptation of CLs loaded with agomelatine or 5-MCA-NAT in rabbits triggered a higher tear secretion than the corresponding eye drops (78% and 59% more, respectively). These data suggest that CLs preloaded with melatonin analogs could be an adequate strategy to combat aqueous tear deficient dry eye disease.

Silicone hydrogel contact lenses retain and document ocular surface lipid mediator profiles

ABSTRACT Clinical relevance A leading reason for patients to abandon their contact lenses is discomfort. Mechanisms and biomarkers for lens discomfort remain to be elucidated. Background Physical stress and tear film interaction are likely factors for lens discomfort. Lipid mediators are generated from polyunsaturated fatty acids. They regulate ocular surface physiology and pathophysiology, are constituents of human tears and may interact with contact lenses. This study set out to determine if hydrogel lenses and silicone hydrogel lenses interact with tear film polyunsaturated fatty acids and polyunsaturated fatty acids-derived mediators. Methods In vitro incubations, rat experiments and analysis of worn human lenses assessed polyunsaturated fatty acids and lipid mediator interactions with lenses. Silicone hydrogel and hydrogel lenses were incubated with lipid mediators and polyunsaturated fatty acids up to 24 hours. Rats were fitted with custom silicone hydrogel lenses and basal tears collected. Silicone hydrogel lenses worn for 2 weeks were obtained from 57 human subjects. Tear and lens lipidomes were quantified by mass spectrometry. Results Silicone hydrogel lenses retained polyunsaturated fatty acids and lipid mediators within 15 minutes in vitro. Lenses contained 90% of total polyunsaturated fatty acids and 83–89% of total monohydroxy fatty acids by 12 hours. Retention correlated with polarity of lipid mediators and lipophilic properties of silicone hydrogel lenses. Polyunsaturated fatty acids and lipid mediators such as lipoxygenase- and cyclooxygenase-derived eicosanoids were present in tears and worn lenses from rats. Worn silicone hydrogel lenses from human subjects established robust and lens-type specific lipidomes with high levels of polyunsaturated fatty acids, lipoxygenase-pathway markers and subject-specific differences in lipoxin A4 and leukotriene B4. Conclusion Worn silicone hydrogel lenses rapidly retain and accumulate tear polyunsaturated fatty acids and lipid mediators. Marked subject and lens type differences in the lipidome may document changes in ocular surface physiology, cell activation or infection that are associated with lens wear. If contact lens discomfort and adverse events induce specific tear and lens fatty acid and lipid mediator profiles warrants further studies.

Controlled release of naringenin from soft hydrogel contact lens: An investigation into lens critical properties and in vitro release

The naringenin (NAR)-impregnated hydrogel lenses (nesofilcon A material) were manufactured in this study with the feasibility to achieve controlled daily drug release. The lenses were fabricated using a comparable commercial-standard process, utilizing injection molding and thermal curing approaches. NAR-loaded lenses were prepared by both direct entrapment and ‘soak and release’ methods. Their critical properties were tested to ISO standards and comparable to the commercial lenses. NAR was fully characterized by studying its physical and chemical stability throughout the manufacturing processes using thermal analysis, high performance liquid chromatography and X-ray diffraction analysis. The NAR-loaded lenses showed > 97% light transmission, >75% water content, 0.50–0.53 ± 0.06 MPa tensile strength, with a lens diameter of 14.1 ± 0.1 mm. Lens polymerization kinetics were studied using differential scanning calorimetry. NAR released from the lens, prepared by a direct entrapment approach, followed a diffusion-controlled mechanism, and provided a controlled drug release of 72–82% for 24 h. A faster release rate was observed for NAR-loaded lenses prepared by a soak and release method, with over 90% of NAR was releasedin the first five hours.

The short-term effect of contact lens wear on blink characteristics

PurposeThe aim of this pilot study was to investigate the initial effect of contact lens wear on spontaneous blink characteristics. MethodsThis was a randomised, crossover pilot study. Spontaneous blinking was recorded using a high-speed infrared camera in ten subjects with three different soft contact lenses (spherical hydrogel, spherical silicone hydrogel and toric hydrogel), one rigid contact lens and without contact lenses. Custom semi-automated software was used to determine palpebral aperture height, interblink interval (IBI), blink speed, blink completeness and blink duration. ResultsThe IBI was significantly greater for non-lens wear compared with the silicone hydrogel [ratio (95% CI): 1.34 (1.16, 1.55), p < 0.0001], toric hydrogel [1.28 (1.10, 1.48), p = 0.0001] and rigid corneal lenses [1.48 (1.27, 1.73), p < 0.0001]. The spherical silicone hydrogel lens showed greater closing-phase speed than non-lens wear [mean difference (95% CI): 27.4 (5.6, 49.1) mm/s, p = 0.006]. Shorter total blink duration was found for non-lens wear compared with any of the lens types [spherical hydrogel: ratio 0.89 (0.81, 0.98), p = 0.01; spherical silicone hydrogel: 0.87 (0.80, 0.95), p = 0.0001; toric hydrogel: 0.90 (0.83, 0.98), p = 0.004; and rigid corneal: 0.88 (0.82, 0.96), p = 0.0004]. Opening-phase speed (p = 0.12) and blink completeness metrics (all p > 0.5) were not influenced by wearing condition. ConclusionThis work showed that short-term contact lens wear influenced the palpebral aperture height, IBI, speed and duration of the blink, and the effect is dependent on the contact lens type. The completeness of the blink was not altered by contact lens wear. Future work should be conducted to assess the effect of long-term wear of different contact lens types on blink characteristics. The measurement of spontaneous blinking characteristics represents an immediate, sensitive and non-invasive evaluation of the impact of a contact lens on the ocular surface.

Characterization and analysis of extended-wear silicone hydrogel contact lenses utilizing novel silicone macromers.

Contact lenses are one of the most successful biomaterials in history with a global market estimated to be worth over $17 billion in 2025. Silicone hydrogel contact lenses dominate the market and are complex biphasic biomaterials with several critical material properties needed for clinical use. Careful consideration of composition and chemistry is needed to identify formulations of lenses meeting all commercial standards with the potential for improved manufacturability, cost, and/or next generation use. Four silicone macromers were investigated in this work with varying symmetry of siloxane units and macromer structure, number of siloxane groups, branching, length, and concentration. Novel silicone hydrogel lenses were produced and evaluated for optical transmittance, elastic modulus, oxygen transmissibility, water content, and surface wettability. Several lenses met commercial standards and demonstrated an increase in oxygen permeability (Dk) and inverse relationship with elastic modulus and siloxane concentration, respectively. A hydrophobic/hydrophilic ratio below 1.4 was needed for a co‐continuous water phase. Substitution of methoxypropyl groups for butyl groups increased hydrophobic microdomains leading to decreased optical quality and mechanical properties. Generally, fluorine‐containing silicone macromers allowed for a wider range of successful compositions, and above a certain hydrophilic composition, the presence of trifluoropropyl groups resulted in improved solubility and optically clear lenses. Data also showed asymmetric siloxane macromers have potential to meet critical lens properties at lower overall siloxane content. New lens materials with wider composition ranges meeting all clinical lens properties is a significant challenge and may significantly expand the field.

Preparation and Analysis of High Functional Silicone Hydrogel Lens Containing Metal Oxide Nanoparticles by Photopolymerizaion

Preparation and Analysis of High Functional Silicone Hydrogel Lens Containing Metal Oxide Nanoparticles by Photopolymerizaion

Preparation and Characterization of Biocompatible and High Functional Hydrogel Lenses Containing Collagen Material

Preparation and Characterization of Biocompatible and High Functional Hydrogel Lenses Containing Collagen Material

Biocompatible soft hydrogel lens as topical implants for diabetic retinopathy

Fashioned contact lenses can be converted into novel drug delivery vehicles. Ocular disease like diabetic retinopathy is a major microvascular complication that mainly affects retina. Delivery of pharmaceuticals to retina is always challenging. Commercial contact lens can be replaced with drug loaded hydrogels as topical intraocular implants. Such hydrogel lens can be developed in precise method and used as implants in mice models. The work demonstrated the preliminary investigations using optical imaging modality where the hydrogel lens can be used as payload carrier for retinopathy. as non-invasive implants applicable for mice models.

In Vivo Wettability of HydraGlyde® Silicone Hydrogel Lens With and Without HydraGlyde® Containing Lens Care Solution

Contact lens care solutions are readily available over-the-counter at any pharmacy, optical shop, or eye care specialist centers. The use of a non-compatible solution may damage or alter the material of the contact lens, and may cause changes in the efficiency of the lens, thereby reducing comfort of the wearer. Hence, this research was carried out to determine the wettability of HydraGlyde® Silicone Hydrogel lens with and without HydraGlyde® containing lens care solutions. The right eye of 25 subjects (mean age: 22.8 ± 1.3 years old) were studied. The subjects needed to come for two visits [1 week apart] at approximately the same time of the day. Each subject received the pre-soaked lenses with and without HydraGlyde® Moisture Matrix randomly. The subjects wore the lenses for 8 h. Non-Invasive Tear Breakup Time (NIKBUT) was measured using OCULUS® Keratograph 5M, followed by a subjective questionnaire response.Parametric paired t-test showed no significant differences in PLTF NIKBUT baseline (16.25 ± 3.75 s)and after 8 h of lens wear (15.02 ± 3.81 s) when lenses soaked in a solution with HydraGlyde® Moisture Matrix (p &gt; 0.05). However, a significant difference was found in PLTF NIKBUT baseline (16.16 ± 2.79 s), and after 8 h of lens wear (14.74 ± 3.73 s) when lenses were soaked in a solution without HydraGlyde® Moisture Matrix (p &lt; 0.05). The change in the PLTF NIKBUT baseline and after 8 h of lens wear for the solution with and without HydraGlyde® Moisture Matrix (−1.23 ± 3.89 s and 1.68 ± 3.58 s respectively) were not statistically significant (p &gt; 0.05). The subjective questionnaire revealed a preference towards a solution with HydraGlyde® Moisture Matrix with a mean score of 68.84 ± 15.36% compared to without HydraGlyde® Moisture Matrix with a mean score of 62.80 ± 14.00% (p &lt; 0.05). A lens care solution con-taining HydraGlyde® Moisture Matrix is advised to be prescribed along with HydraGlyde® silicone hydrogel lens to achieve optimum lens performance.

Wear Experience of a Water Surface Daily Disposable Contact Lens in Existing Silicone Hydrogel Planned Replacement Lens Wearers.

PurposeThe health benefits of silicone hydrogel lens materials and a daily replacement modality have been demonstrated in previous studies; however, existing planned replacement lens wearers may resist changing to a new lens replacement schedule. The purpose of this study is to evaluate the wear experience of satisfied planned replacement silicone hydrogel wearers when refit into a silicone hydrogel daily disposable lens.Patients and MethodsIn this open-label, non-comparison study, satisfied wearers of two week planned replacement contact lenses were evaluated for inclusion criteria and refit with optimized prescriptions in their habitual lenses. At a follow-up visit one week later, participants were refit with the study daily disposable lenses and completed visual analog scale (VAS) surveys of initial quality of vision, comfort, and satisfaction. Participants returned for a final visit after two weeks of wearing the study daily disposable lenses. At the final visit, VAS surveys for both overall and end of day (EOD) vision, comfort, and dryness were completed. Overall median and interquartile range (IQR) were assessed for all surveys in the study.ResultsThirty individuals completed the study (29.1 ± 7.8 years old; 19 female). Median (IQR) results for the initial impression VAS surveys were 92.50(11.75) for quality of vision, 92.50(18.00) for comfort, and 93.00(18.00) for satisfaction. Final VAS survey results revealed median scores of 87.50(25.00) for EOD quality of vision and 82.50(51.25) for EOD comfort. The median overall quality of vision was 91.00(17.00) and overall comfort was 93.00(28.50). Median (IQR) overall dryness was 28.50(49.00) and median EOD dryness was 30.50(64.25).ConclusionThe findings of this study suggest that providers can successfully refit satisfied wearers of early generation silicone hydrogel planned replacement lenses into a new generation silicone hydrogel daily disposable lens while maintaining satisfaction.

Assessment of a novel silicone hydrogel daily disposable lens among physically active subjects

Purpose: Physical exercise can change the body’s hydration status and blink rate that results in hyperosmotic tears. Increased osmolarity is related to contact lens (CL) dryness. Maintaining ocular surface homeostasis while wearing CLs is complex and has led to innovations in lens material and design. This study evaluated wear experiences of subjects that actively take part in regular sport or physical activity (PA) and subjects that don’t (NPA) while wearing a novel kalifilcon A (KA) daily disposable silicone hydrogel lens (DDSH) containing moisturizers and osmoprotectants.

Silicone Hydrogel Contact Lenses Retain and Document Ocular Surface Lipid Mediator Profiles

Purpose: Physical stress and tear film interaction are likely factors for contact lens discomfort. Bioactive lipid mediators (LM) that are generated from ω-3 and ω-6 polyunsaturated fatty acids (PUFA) regulate ocular surface physiology and pathophysiology, are constituents of human tears and potential biomarkers. Whether silicone hydrogel lenses interact with tear LM and PUFA was investigated.

Self-assembly and cleaning and wettability of a polysaccharide-surfactant system formed from the cationic hydroxypropyltrimethyl ammonium chloride chitosan and nonionic sucrose lauric acid ester

Contact lens care solution was prepared via hydroxypropyltrimethyl ammonium chloride chitosan (HACC) and sucrose lauric acid ester (SML) via self-assembly in borate buffer solution (BBS). The elution efficiency of lipids, micellization, and wettability properties of HACC-SML in BBS was studied systematically using high-performance liquid chromatography (HPLC), dynamic light scattering (DLS), zeta potential, surface tension, and contact angles methodologies. The elution efficiency of the lipid increased from 46.98% to 65.68%, whereas DLS and zeta potential data varied with the addition of SML. These caused the shrinkage of micelles, and the system became stable, and further revealed that SML was a non-ionic biosurfactant with excellent performance. The result of surface tension at water-air and contact angles on silicone hydrogel lens at 25 °C showed that SML has outstanding adsorption capacity with an increased degree of wetting, ensuring the comfort and safety of wearing.

Amoebicidal Activity of Poly-Epsilon-Lysine Functionalized Hydrogels

PurposeTo determine the amoebicidal activity of functionalized poly-epsilon-lysine hydrogels (pɛK+) against Acanthamoeba castellanii.Methods A. castellanii trophozoites and cysts were grown in the presence of pɛK solution (0–2.17 mM), pɛK or pɛK+ hydrogels, or commercial hydrogel contact lens (CL) for 24 hours or 7 days in PBS or Peptone-Yeast-Glucose (PYG) media (nutrient-deplete or nutrient-replete cultures, respectively). Toxicity was determined using propidium iodide and imaged using fluorescence microscopy. Ex vivo porcine corneas were inoculated with A. castellanii trophozoites ± pɛK, pɛK+ hydrogels or commercial hydrogel CL for 7 days. Corneal infection was assessed by periodic acid–Schiff staining and histologic analysis. Regrowth of A. castellanii from hydrogel lenses and corneal discs at 7 days was assessed using microscopy and enumeration.ResultsThe toxicity of pɛK+ hydrogels resulted in the death of 98.52% or 83.31% of the trophozoites at 24 hours or 7 days, respectively. The toxicity of pɛK+ hydrogels resulted in the death of 70.59% or 82.32% of the cysts in PBS at 24 hours or 7 days, respectively. Cysts exposed to pɛK+ hydrogels in PYG medium resulted in 75.37% and 87.14% death at 24 hours and 7 days. Ex vivo corneas infected with trophozoites and incubated with pɛK+ hydrogels showed the absence of A. castellanii in the stroma, with no regrowth from corneas or pɛK+ hydrogel, compared with infected-only corneas and those incubated in presence of commercial hydrogel CL.ConclusionspɛK+ hydrogels demonstrated pronounced amoebicidal and cysticidal activity against A. castellanii. pɛK+ hydrogels have the potential for use as CLs that could minimize the risk of CL-associated Acanthamoeba keratitis.

Laccase-catalyzed surface oxidation of poly(2-hydroxyethyl methacrylate) contact lens hydrogel using polyvinylamine-graft-TEMPO as mediator

Surface oxidation is a commonly used surface modification method for macromolecular biomaterials, which can increase the surface hydrophilicity and biocompatibility, and provide active sites for subsequent functional modifications. The nitroxyl radical, as represented by TEMPO, could act as an electron transfer mediator in the catalytic oxidation reaction in aqueous phase. By immobilizing TEMPO on a water-soluble polymer carrier polyvinylamine (PVAm) and using laccase as a catalyst, the surface of poly(2-hydroxyethyl methacrylate) (pHEMA) contact lens hydrogel can be selectively oxidized. Herein, polyvinylamine-graft-TEMPO was used as a polymeric electron transfer mediator to confine the oxidation reaction within the surface of the pHEMA hydrogel. The oxidized hydrogel with surface aldehydes was subsequently coated with hyaluronic acid, which gained low rate of water loss and low protein adsorption. This surface oxidation method can provide new ways for the activation, modification, and function expansion for the surface of polymeric biomaterials especially contact lens hydrogels.

Incidence of Corneal Inflammation of Varying Severity among Contact Lens Wearers

The human cornea is an avascular, transparent tissue that permits or allows light rays to enter or reach the retina. The cornea is made up of several layers, each of which plays an important role in preserving the transparency and power of cornea. The epithelium, Bowmans layer, Descemet’s membrane and endothelium are the layers of the cornea. This study aimed to discover the incidences of severe and non-severe corneal inflammation amongst wearers of modern technology touch lenses. Studies on touch lens users providing with a corneal ulcer/infiltrates were reported. On the basis of severity, a medical severity matrix was utilized among cases of severe and non-severe corneal inflammation. There was a large distinction in severe corneal infection among ew-hydrogel and ew-silicone hydrogel. When it comes to evaluating touch lens-related corneal inflammation, a medical severity matrix is available in hand. Wearers of contact lenses who sleep with them have a appreciably low risk of severe corneal inflammation than those who simplest put on lenses for the duration of the day. Those cases who everyday sleep with lenses have a 5-fold lower risk of severe corneal inflammation as compared day-to-day hydrogel lenses for prolonged utilization.

Poly (Ethylene Glycol) Methyl Ether Methacrylate-Based Hydrogel and Cerium(IV) Oxide Nanoparticles as Ophthalmic Lens Material.

The functional hydrogel lens containing 2-hydroxyethylmethacrylate (HEMA) was manufactured by thermal polymerization. The physical properties of the produced hydrogel lens were measured and analyzed. In this study, HEMA, ethylene glycol dimethacrylate (EGDMA), and azobisisobutyronitrile (AIBN) were used for thermal copolymerization. Additionally, poly (ethylene glycol) methyl ether methacrylate (PEGMEMA), 3-(Triethoxysilyl) propyl isocyanate (TEPI), and cerium(Ⅳ) oxide nanoparticles were used as additives to make a functional hydrogel lens. The mixture was heated at 100 °C for 90 min to produce the hydrogel ophthalmic lens by the cast mold method. The resulting physical properties showed that the water content and refractive index of the sample were in the ranges of 38.06~42.11% and 1.426~1.436, respectively. The addition of cerium oxide nanoparticles lowered the contact angle and allowed the hydrogel lens to block UV light. The tensile strength was also improved by 52.13% through cerium oxide nanoparticles, and up to 123.4% by using TEPI. Based on the results of this study, the produced ophthalmic lens is suitable for durable, UV-blocking high-performance lenses.

Preparation and Analysis of Functional Silicone Hydrogel Lenses Containing ZrO₂ and Antimony Tin Oxide Nanoparticles.

This study prepared silicone hydrogel ophthalmic lenses using 2-hydroxyethylmethacrylate (HEMA), synthesized silicone monomer (SID), dimethylarsinic acid (DMA), N-hydroxyethyl acrylamide (HEA), ethylene glycol dimethacrylate (a crosslinking agent, EGDMA), and azobisisobutyronitrile (an initiator, AIBN). Also, Zirconium oxide (ZrO₂), antimony tin oxide (ATO) nanoparticles were added to the silicone hydrogel material to analyze the characteristics of the nanoparticles. The mixture was heated at 130 °C for 2 hours to produce the ophthalmic contact lens by cast mould method. As a result, the manufactured silicone hydrogel lens was prepared having high oxygen permeability and tensile strength while satisfying the basic requirements of ophthalmic hydrogel lens materials. Also, the addition of ZrO₂ NPs increased tensile strength of the manufactured lens, and ATO NPs were found to improve wettability. Therefore, ZrO₂ and ATO nanoparticles can be used effectively as additives for functional ophthalmic silicone hydrogel lenses.

Silver Nanoparticles Using Eucalyptus or Willow Extracts (AgNPs) as Contact Lens Hydrogel Components to Reduce the Risk of Microbial Infection.

Eucalyptus leaves (ELE) and willow bark (WBE) extracts were utilized towards the formation of silver nanoparticles (AgNPs(ELE), AgNPs(WBE)). AgNPs(ELE) and AgNPs(WBE) were dispersed in polymer hydrogels to create pHEMA@AgNPs(ELE)_2 and pHEMA@AgNPs(WBE)_2 using hydroxyethyl-methacrylate (HEMA). The materials were characterized in a solid state by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC) and attenuated total reflection spectroscopy (ATR-FTIR) and ultraviolet visible (UV-vis) spectroscopy in solution. The antimicrobial potential of the materials was investigated against the Gram-negative bacterial strain Pseudomonas aeruginosa (P. aeruginosa) and the Gram-positive bacterial strain of the genus Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus), which are involved in microbial keratitis. The percentage of bacterial viability of P. aeruginosa and S. epidermidis upon their incubation over the pHEMA@AgNPs(ELE)_2 discs is interestingly low (28.3 and 6.8% respectively), while the inhibition zones (IZ) formed are 12.3 ± 1.7 and 13.2 ± 1.2 mm, respectively. No in vitro toxicity of this material towards human corneal epithelial cells (HCEC) was detected. Despite its low performance against S. aureus, pHEMA@AgNPs(ELE)_2 could be an efficient candidate towards the development of contact lenses that reduces microbial infection risk.

Evaluation of silicone hydrogel contact lenses based on poly(dimethylsiloxane) dialkanol and hydrophilic polymers

Silicone hydrogel lenses were prepared by copolymerizing PDMS-PEGMA macromer (PGP) with various combinations of DMA, NVP, and PEGMA through UV initiated polymerization process. The resultant PGP macromer were characterized by gel permeation chromatography (GPC), and scanning electron microscope (SEM-EDS). Characterization of all the resultant co-polymers included Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), equilibrium water content (EWC), oxygen permeability (Dk), optical transparency, contact angle, mechanical properties, zeta potential, protein deposition, and cytotoxicity. The results show that higher content of hydrophilic polymers increased water uptake ability as well as improved hydrophilicity and modulus of silicone hydrogel lenses; however, oxygen permeability decreased with the decrease of PDMS content (145 barrers of PGP to 37 barrers of DP0). In addition, these silicone hydrogel lenses exhibited relatively optical transparency, anti-protein deposition, and non-cytotoxic according to an in vitro L929 fibroblast assay. Therefore, these silicone hydrogel polymers would be applicable for making contact lens.