Silicone Hydrogel Contact Research Articles

Multi-purpose Disinfecting Solutions only Partially Inhibit the Development of Ocular Microbes Biofilms in Contact Lens Storage Cases.

PURPOSE:Certain ocular resident or pathogenic microbes may remain viable in the presence of multi-purpose disinfectant solutions (MPDSs), subsequently developing biofilms inside contact lens storage cases (CLSCs) which pose a risk of infection to wearers. This study evaluated the formation of ocular microbiota biofilms exposed to three top selling MPDS.METHODS:Crystal violet assay was carried out for the verification of biofilm formation. The in vitro assays evaluated Pseudomonas aeruginosa UFPEDA 416 and Staphylococcus aureus UFPEDA 02 exposure of 48 h to MPDS, as well as the use of 40 KHz ultrasound at the beginning and with 24 h immersion in the MPDS. Subsequently, in vivo assays evaluated the formation of microbial biofilms on the CLSC walls containing silicone-hydrogel contact lenses immersed in MPDS from 15 healthy volunteer patients, who had been wearing the lenses for 7 days.RESULTS:Biofilms were inhibited by 26%–98% in the in vitro assays, with a statistically significant difference only for P. aeruginosa UFPEDA 416 exposed to diluted MPDS. Most inhibitions occurred moderately and weakly. In addition, adherent cells were detected in more than 90% of the tests. Biofilm was not inhibited in more than one third of the results, nor was it disturbed, especially with the ultrasound treatments. The average of obtained optical densities at 590 nm was between 0.6 and 0.8 in the in vivo assays. The results were similar between the CLSC right and left wells. There was a correlation between microbial biofilm formation and the type of MPDS tested, with statistical difference between the three treatments.CONCLUSION:MPDS promoted a partial inhibition of microbial biofilm formation but only one MPDS proved to be more effective in vitro and in vivo. This study, however, could not distinguish the effect of possible errors in the good hygiene practices of the users.

Micromechanical measurement of adhesion of dehydrating silicone hydrogel contact lenses to corneal tissue

Adhesion properties, which can vary with multiple factors, of silicone hydrogel contact lenses are important to their performance and comfort in the eye. In this study, we developed and used a simple, representative testing system and method to study the adhesive interactions of different silicone contact lenses (balafilcon A and senofilcon A) on polished titanium alloy and porcine whole eye cornea under dehydrating conditions. Adhesive interactions for senofilcon A varied by hydration state for both corneal and titanium adhesion, starting low, rising to a maximum and falling with dehydration time and dehydration state. Balafilcon A showed a rise and fall against titanium, but retained a relatively constant adhesive interaction with corneal tissue over dehydration time. Senofilcon A reached the highest adhesion forces (400 mN) within 5 to 10 min of testing against cornea, then dropped with time after that. Johnson-Kendall-Roberts (JKR) theory was applied to determine the surface energy of the lenses, and work of adhesion (WOA) was also determined for both lenses. Similar trends as observed with the force-hydration curves were seen with surface energy and work of adhesion as well (peak surface energy of 8 N/m and work of adhesion of 80 µJ for senofilcon A). Video imaging of the adhesive interactions showed significant corneal deformation taking place during testing, and post-test analysis shows damage to the corneal tissue. This method could be used to assess pre-clinical performance of long-lasting contact lenses and the role of hydration state. Statement of significanceAdhesion properties of contact lenses play significant roles in their performance and comfort in the eye. Adhesion is influenced by polymer chemistry, counterface materials and hydration state of the contact lenses. However, no test method has been developed to directly study the adhesion properties between contact lenses and corneal tissue during the dehydration process. Our work aims to fill this gap by developing testing and analysis methods for evaluating the adhesive interactions in vitro between contact lenses of different chemistries and properties and different counter surfaces under dehydrating conditions over time. Our study shows that adhesive interactions of contact lenses are highly dependent on polymer type, surface treatment, counterface material and hydration state.

In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials

PurposeSeveral clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials. MethodsConventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials. ResultsBoth conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p < 0.05). Senofilcon A and somofilcon A did not exhibit uptake of any of these cytokines (p > 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05). ConclusionThe contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.

Antifouling Silicone Hydrogel Contact Lenses with a Bioinspired 2-Methacryloyloxyethyl Phosphorylcholine Polymer Surface.

Inspired by the cell membrane surface as well as the ocular tissue, a novel and clinically applicable antifouling silicone hydrogel contact lens material was developed. The unique chemical and biological features on the surface on a silicone hydrogel base substrate were achieved by a cross-linked polymer layer composed of 2-methacryloyloxyethyl phosphorylcholine (MPC), which was considered important for optimal on-eye performance. The effects of the polymer layer on adsorption of biomolecules, such as lipid and proteins, and adhesion of cells and bacteria were evaluated and compared with several conventional silicone hydrogel contact lens materials. The MPC polymer layer provided significant resistance to lipid deposition as visually demonstrated by the three-dimensional confocal images of whole contact lenses. Also, fibroblast cell adhesion was decreased to a 1% level compared with that on the conventional silicone hydrogel contact lenses. The movement of the cells on the surface of the MPC polymer-modified lens material was greater compared with other silicone hydrogel contact lenses indicating that lubrication of the contact lenses on ocular tissue might be improved. The superior hydrophilic nature of the MPC polymer layer provides improved surface properties compared to the underlying silicone hydrogel base substrate.

Impact of modulus of elasticity of silicone hydrogel contact lenses on meibomian glands morphology and function

ABSTRACT Clinical relevance: It is important to investigate the effect of modulus of silicone hydrogel contact lens on meibomian glands. Evaluating meibomian gland health and function in follow-up appointments should be considered, with the option of changing lens modulus. Background: To evaluate and compare the effect of modulus of elasticity of silicone hydrogel contact lenses on morphological and functional parameters of the meibomian glands. Methods: A prospective study was conducted on soft silicone hydrogel contact lens wearers of different modulus of elasticity and age and gender-matched controls. Morphological and functional parameters were assessed along with standard patient evaluation of the eye dryness questionnaire. Results: A statistically significant difference was noted in meibomian gland loss in the upper lid (percent) between the low modulus (18.23 ± 6.63) and high modulus group (27.40 ± 10.21) (p < 0.001) and between high modulus (27.40 ± 10.21) and non-contact lens wearers (19.57 ± 7.65) (p = 0.001). The current study reported significantly higher total meiboscore grading in the high modulus group 3 (2-3) compared to the low modulus 2(2-3) (p = 0.007) and non-contact lens wearing groups 2 (2-3) (p = 0.012). Meibum quality was significantly compromised in the high modulus group 1 (0-1) compared to the low modulus 0 (0-0.75) group (p = 0.01). Standard patient evaluation of the eye dryness questionnaire was found to be significantly higher (p = 0.01) in high modulus 4 (2-8) compared to low modulus wearers 2 (2-4). A significant difference was noted (p < 0.001) in corneal staining grading only between high modulus 0 (0-1) and non-contact lens wearers 0 (0-0) group. A positive correlation was noted in the low modulus group between total meiboscore and meibomian gland expressibility (Rs = +0.69, p < 0.001) and also noted between standard patient evaluation of the eye dryness questionnaire scoring and meibomian gland expressibility (Rs = +0.45, p = 0.012) in the high modulus group. Conclusion: Higher modulus of elasticity of silicone hydrogel contact lens may influence meibomian gland morphology and function over a period of contact lens wear.

Efficacy of two silicone-hydrogel bandage contact lenses after corneal crosslinking

ABSTRACT Silicone-hydrogel (SiH) contact lenses are frequently used as a bandage after anterior segment surgical procedures. Several types of lenses may exhibit clinical performances with different characteristics. This study aims to evaluate the efficacy of two SiH contact lenses following corneal crosslinking (CXL). Forty-nine keratoconus patients scheduled for consecutive CXL surgery in both eyes were included in this comparative, double-blind, prospective study. A Balafilcon A (Pure Vision 2 HD, Bausch+Lomb, Rochester, NY, USA) or Lotrafilcon B (Air Optix Aqua, Ciba Vision, Duluth, GA, USA) lens was fitted in a randomised fashion in the eyes at the end of the CXL. Remaining epithelial defect area measured by slitlamp biomicroscopy, subjective level of pain and discomfort with visual analogue scale (VAS) and total number of oral analgesics taken were evaluated and compared at post-operative days 0, 1, 2 and 3. The average epithelial defect size was significantly smaller in the eyes with Lotrafilcon B than the eyes with Balafilcon A at post-operative Day 1 (31.2 ± 4.3 mm2 and 33.8 ± 5.2 mm2, respectively, p < 0.001) and Day 2 (8.2 ± 3.6 mm2 and 10.5 ± 5.4 mm2, respectively, p = 0.039). There was no statistically significant in the average epithelial defect size between the groups at Day 3 (p = 0.859). Re-epithelialisation time was similar in both groups (p = 0.317) There was no statistically significant difference in VAS scores regarding the lens type in any post-operative follow-up. The mean oral analgesic numbers were similar in both groups (p = 0.217). SiH contact lenses can be used as an effective bandage for corneal re-epithelialisation after CXL. The material and features of bandage contact lens used after CXL may affect the corneal re-epithelialisation process. Lotrafilcon B lens showed faster re-epithelialisation at post-operative days 1 and 2 after CXL.

Factors affecting microbial contamination on the back surface of worn soft contact lenses

Purpose: To investigate the effect of lens packaging type, the presence of chelating agent EDTA in the packaging solution and microbial contamination of the fingers on the level and rate of microbial contamination on the back surface of worn silicone hydrogel and hydrogel contact lenses.

Comparison of the clinical performance of a novel silicone hydrogel and a HEMA-based daily disposable contact lens

Purpose: Verofilcon A is a novel, daily disposable, silicone hydrogel contact lens with “SmartSurface” chemistry. The objective of this study was to assess overall lens preference, as well as overall comfort, handling and quality of vision of verofilcon A compared to a commercially available HEMA-based daily disposable lens (etafilcon A).

Assessing the clinical performance of a new daily disposable silicone hydrogel contact lens

Purpose: To assess the clinical performance of a new daily disposable (DD), silicone hydrogel contact lens made from verofilcon A material.

Characterizing the surface properties of daily disposable contact lens materials

Purpose: Using surface chemistry, a daily disposable silicone hydrogel (SiHy) contact lens with unique surface properties (verofilcon A) was developed. This novel lens material with “SMARTSURFACE” technology should provide a more wettable surface than other SiHy lens materials. This study used an in vitro model to characterize the aqueous film stability of this lens and compared with other commercial contact lenses.

Clinical lens fit characteristics of a new silicone hydrogel daily disposable and two commercially available daily disposable contact lenses

Purpose: A new silicone hydrogel (SiHy) contact lens (verofilcon A; 51% water content) with “SmartSurface” has been developed. The intent of these studies was to assess contact lens fit characteristics of a new SiHy daily disposable (verofilcon A) and commercially available HEMA-based (etafilcon A) and SiHy (somofilcon A) daily disposable contact lenses.

Clinical lens fit characteristics of a new daily disposable toric silicone hydrogel contact lens

Clinical lens fit characteristics of a new daily disposable toric silicone hydrogel contact lens

Eye Care Practitioner (ECP) drivers and new wearer attitudes on 1-day silicone hydrogel lenses in Italy

Purpose: This research study sought to understand what is driving eye care professionals (ECPs) in Italy when recommending 1-day silicone hydrogel contact lenses (1DSiHy CLs) and new wearer attitudes to the lenses.

Sodium-Sensitive Contact Lens for Diagnostics of Ocular Pathologies.

The ability to measure all the electrolyte concentrations in tears would be valuable in ophthalmology for research and diagnosis of dry eye disease (DED) and other ocular pathologies. However, tear samples are difficult to collect and analyze because the total volume is small and the chemical composition changes rapidly. Measurements of electrolytes in tears is challenging because typical clinical assays for proteins and other biomarkers cannot be used to detect ion concentrations tears. Here, we report the contact lens which is sensitive to sodium ion (Na+), one of the dominant electrolytes in tears. The Na ions in tears is diagnostic for DED. Three sodium-sensitive fluorophores (SG-C16, SG-LPE and SG-PL) were synthesized by derivatizing the sodium green with 1-hexadecyl amine, 1-oleoyl-2-hydroxy-sn-glycero-3-phosphoethanolamine or poly-L-lysine, respectively. These probes were bound to modern silicone hydrogel (SiHG) contact lens, Biofinity from Cooper Vision. Doped lenses were tested for sodium ion dependent spectral properties of probes within the contact lens. The probes displayed changes in intensity and lifetime in response to Na+ concentration, were completely reversible, no significant probe wash-out from the lenses, were not affected by proteins in tears and were not removed after repeated washing. These results are the first step to our long-term goal, which is a lens sensitive to all the electrolytes in tears. We presented design, synthesis and implementation of three new sodium sensitive probes within a silicon hydrogel lens. Contact lenses to measure the other electrolytes in tears can be developed using the same approach by synthesis and testing of new ion-sensitive fluorophores.

PREPARATION, OXYGEN PERMEABILITY, OPTICAL TRANSPARENCY,WATER CONTENT,PROTEIN ADSORPTION AND EVALUATION OF BACTERIAL ADHESION PROPERTIES OF NEW SILICONE HYDROGEL THROUGH MODULATING SILICONE AND HYDROPHILIC MONOMER

Silicone Hydrogel (SiHy) contact lenses are extremely fruitful in compare is onto preceding soft lenses; they were established to offer superior oxygen permeability. In the following paper, the hydrogel contact lenses based on silicone were made through the polymerization of 3- (methacryloyloxy) propyltris(trimethylsiloxy) silane (TRIS) with N,N dimethylacryl amide (DMA), Methyl methacrylate (MMA),and 2-hydroxyethyl methacrylate (HEMA). The features of silicone hydrogel lenses were studied depending on the approaches like equilibrium water component, oxygen permeability, optical transparency, protein adsorption, as well as cell toxicity.The outcomes revealed which the TRIS component in all makings rose the oxygen penetrability and decreased the equilibrium water component, while the DMA&amp; HEMA participated the hydrophilicity of the silicon hydrogels and increases the equilibrium water content (EWC)%. The higher worth of oxygen penetrability was 102barrers, conforming to an equilibrium made of water component of 66%. generally, the silicone hydrogels in this work displayed decent oxygen permeability as well as optical transparency and anti protein adsorption. Hence forth, those polymers made of silicone hydrogel might be possible for manufacturing contact lens.

Effect Of Silicon Hydrogel Contact Lens Materials On Tear Film Stability And Central Corneal Radius Of Curvature: A Comparative Study Of Balafilcon A And Lotrafilcon B

The keratometer was adjusted and focused on the right eye. With the mires in focus, the subject was asked to blink once and refrain from blinking. A stopwatch was started immediately after the last complete blink. At the first appearance of any distortion of the focusing mire, the stopwatch was stopped and the time noted. If subject blinks between measurements, the test is halted, and then repeated after several blinks. The interval between the last blink and the doubling/distortion of mires was recorded in seconds as the NIBUT. Five measurements were taken for each subject and the average of three closest NIBUT values was taken as the mean value.Contact Lens Materials and Corneal Radius of Curvature: -The corneal curvature of the subject was measured immediately after NIBUT assessment. The distorted mire was sharply focused with the focusing knob. The corneal curvature was converted to corneal radius of curvature (in millimetres) by dividing 337.5 by the dioptric power of the flatter meridian.RESULTS:25 subjects (50 eyes) were participated in this study. The corneal radius of curvature (CRC) and non-invasive tear break-up time (NIBUT) were assessed with the Bausch and Lomb Keratometer H-135A.Participants were allocated RE with BALAFILCON A and LE with LOTRAFILCON B, Single Blinded – (Patient). The difference in mean NIBUT between pre-insertion,8thday ,15thday ,22th day and 29thday of BALAFILCON A and LOTRAFILCON B Contact Lens wear was statistically significant where p value is <0.05 with paired T test. The difference in mean CRC between pre-insertion,8thday ,15thday ,22 thday and 29thday of BALAFILCON A and LOTRAFILCON B Contact Lens wear was statistically not significant where p value is> 0.05 with paired T test.CONCLUSION:Balafilcon A having greater corneal tearfilm stability compare to Lotrafilcon B. The corneal curvature was not significantly affected by any of the Silicone Hydrogel Contact Lens materials during the period under study.

Hidrojel ve Silikon Hidrojel Kontakt Lens Kullanımı ile Konjonktivadaki Koagülaz Negatif Stafilokok Popülasyonu ve Biyofilm Oluşturan Staphylococcus epidermidis Arasındaki İlişki

Objective: The most important bacteria of the conjunctival microbiota are Staphylococcus epidermidis, diphteroid rods, Corynebacterium spp. and Cutibacterium acnes. Especially biofilm formation of S. epidermidis is very important for contact lens related infections. For this purpose, we aimed to examine the changes in the presence of biofilm-forming S. epidermidis and other coagulase-negative staphylococci in conjunctival swabs taken before and after lens usage in 140 patients (90 hydrogel, 50 silicone hydrogel) who were prepared to wear lenses. Methods: Coagulase-negative staphylococci isolated from the conjunctival microbiota identified standard clinical microbiological methods, after identification of S.epidermidis strains with API Staph; Slime production was determined by Congo red agar, standard tube and molecular methods. Results: S.epidermidis was the most frequently isolated species in conjunctival microbiota before and after lens usage. Before lens usage, slime positive S. epidermidis strains were found as 45-50% but after lens usage it was 59% in hydrogel contact lens users and 70.2% in silicone hydrogel contact lens users. For the investigation of slime production, 82 (50.9%) of 161 S. epidermidis strains were found positive by using Congo red agar, 61 (37.8%) by standard tube method and 91 (56.5%) by molecular methods. Conclusion: The result of our study suggests that there are no significant changes in bacterial ratios before and after lens use, but bacteria such as S. epidermidis can predispose to infections by using slime production and contact lens factor. Also; molecular methods and Congo Red Agar method were found to be more reliable than the Standard Tube method.

Interaction of silicone hydrogel contact lenses with lipids – a chronological review

Silicone hydrogel (Si-Hy) contact lenses are a common form of correction of refractive errors and are prescribed by eye care professionals around the world. Si-Hy lenses perform in a complex environment, which is the surface of the eye and the tear film. Therefore, they are exposed to various factors, such as lipid deposits. The aims of this paper are to review available scientific reports on the study of Si-Hy lens interactions with lipids and search for further research objectives. A total of 57 publications were identified and reviewed, from 2003 to 2020. In general, Si-Hy lenses are more likely to accumulate lipid deposits than traditional hydrogel lenses, although there are significant differences between Si-Hy lens materials that may result from different methods used in the studies. The review includes studies on various aspects of interactions between lenses and lipids, such as those concerning the effectiveness of lipids removal from lenses by care solutions. The conclusion points out future research directions, such as measurements of lipid diffusion in Si-Hy lens' matrices.

Surface characterization of a silicone hydrogel contact lens having bioinspired 2-methacryloyloxyethyl phosphorylcholine polymer layer in hydrated state

A silicone hydrogel contact lens material, with a unique chemical and physical structure has been designed for long-term ocular performance. Enhancement of this silicone hydrogel contact lens material was achieved through surface modification using a cross-linkable bioinspired 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which creates a soft surface gel layer on the silicone hydrogel base material. The surface properties of this MPC polymer-modified lens were characterized under hydrated condition revealing, inter alia, its unique polymer structure, excellent hydrophilicity, lubricity, and flexibility. Analysis of the MPC polymer layer in a hydrated state was performed using a combination of a high-resolution environmental scanning electron microscopy and atomic force microscopy. Compared to the silicone hydrogel base material, this surface had a higher captive bubble contact angle, which corresponds to higher hydrophilicity of the surface. In addition, the hydrated MPC polymer layer exhibited an extremely soft surface and reduced the coefficient of friction by more than 80 %. These characteristics were attributed to the hydration state of the MPC polymer layer on the surface of the silicone hydrogel base material. Also, interaction force of protein deposition was lowered on the surface. Such superior surface properties are anticipated to contribute to excellent ocular performance.

Synthesis and Characterization of New Silicone Hydrogels Contact lenses Based on TRIS-DMA-AA-NVP Via Photo Polymerization for Biomedical Application

The purpose of the present work is to designate the synthesis of innovative soft silicone hydrogel contact lenses founded on Acrylic acid (AA) ,N,N dimethylacrylic amide (DMA),and 1-vinyl 2- pyrolidone(NVP) was polymerized via free fundamental polymerization in the existence of 1,6 hexandioldiacrylate (HDODA) as a crosslinker and 1-hydroxycyclohexyl phenyl ketone as photoinitiator. The polymerized materials were characterized fully for its use fullness as an intraocular lens by various techniques. FTIR was implemented to discover the whole conversion of3-(methacryloyloxy) propyl TRIS (trimethylsiloxy) silane monomer into silicone hydrogels contact lens. The silicon hydrogels contact lenses were manufactured from silicon and different hydrophilic monomers, copolymerization of 3-(methacryloyloxy) propyl( TRIS) (trimethylsiloxy) silane with acrylic acid ,N,N-dimethylacrylamide, and N-Vinylpyrrolidone(NVP) with different ratio (70,80,90)%.To explore three sequences of silicone hydrogel ingredients for their classification, water component, transmittance, mechanical feature , oxygen penetrability) Dk), protein adsorption and bacterial connection as potential contact lens materials as well as tackles the connections between water kinship and optical, mechanical, oxygen permeable with biological features.The outcomes displayed that the water affinity might be moderated through the hydrophilic monomers. The Equilibrium Water Component (EWC) rose with increasing hydrophilic monomer value. Generally, the outcomes revealed that visible light transmittance inclines to increase as well as tensile mechanical features obtained in decreasing trend relying on the growing EWC. The Dk worth declined firstly then was rose once the EWC was from 25 to 75%. The sum of Staphylococcus aurous close to the silicone hydrogels surface of the was fell by61 to 140.This work may provide information on preparing functional silicone hydrogels for contact lenses application.