Hydrogel Contact Research Articles

Dynamic Changes of Ocular Surface in First-Time Contact Lens Wearers and the Effective Factors of Contact Lens Discomfort.

PurposeThe purpose of the study is to investigate the dynamic changes in ocular surface indicators in first-time contact lens (CL) wearers and identify the most influential factors in CL discomfort (CLD).MethodsA total of 26 healthy non-CL wearers (26 eyes) were recruited and fitted monthly with disposable hydrogel CLs. Each participant underwent a full ocular surface evaluation, which include Efron grading, tear film breakup time, Schirmer's I test, corneal dendritic cell (DCs) imaging by in vivo confocal microscopy (IVCM), and conjunctival microvasculature evaluation by functional slit-lamp biomicroscopy. CLD was assessed using the Ocular Surface Disease Index questionnaire at baseline, 1 week, 1, 3, and 6 months after wearing it and another 6 months after discontinuing it.ResultsClinical signs and CLD were significantly increased in the first week (p < 0.05). The microvascular response and DC activation peaked at the 1-month interval (p < 0.05). During CL wear, CLD is positively correlated with corneal staining (B = 0.238, p = 0.002), papillary conjunctivitis (B = 0.245, p < 0.001), and microvascular blood flow velocity (B = 0.353, p < 0.001). After discontinuation, only DC activation remained elevated at 6 months, whereas the other signs recovered.ConclusionsThe first week of CL wear was the main period for the appearance of ocular surface clinical signs, and the first month was the main period for the activation of subclinical inflammation. Corneal staining and conjunctival microvascular response are the main factors affecting CLD. Even if the clinical signs recover after discontinuing wear, subclinical inflammation may persist.

Compliance versus Risk Awareness with Contact Lens Storage Case Hygiene and Replacement.

Compliance with hygiene and replacement of contact lens (CL) storage cases is key to avoid CL contamination and anterior ocular surface complications. However, compliance levels with these accessories remain low, even in patients with awareness of the risk associated with noncompliance. This study aimed to determine level of compliance with common practices regarding CL storage case hygiene and replacement, type of information provided by practitioners, and risk perception. An ad hoc self-reported survey was used to collect demographic and CL wear details, compliance with storage case care, type of received information, and risk perception (in a 1-to-5 scale). Inferential statistics explored the relationship of demographic details and type of received information with compliance and risk perception. Nondaily disposable wearing participants returned 299 completed surveys, with a median age of 24 years (76.9% females). Monthly replacement silicone hydrogel CLs and multipurpose solutions were predominant. Self-reported compliance with storage case care was poor, with 19.1% of respondents never cleaning their cases, 68.6% exposing them to tap water, and 26.4% failing to replace them within 6 months of acquisition. Two-thirds of respondents received specific information on case maintenance, mainly in oral form. Perceived risk associated with poor-compliance practices was high (median values of 4 and 5), and increased with educational level (P = .02, regarding handwashing; P = .03, regarding case hygiene), with years of CL wear experience (P < .001, regarding handwashing), in those patients provided with specific information on CL case care (P = .01, regarding case replacement). Compliance with CL storage case hygiene and replacement was generally poor, although awareness of risk associated with noncompliance was high and influenced by factors related to demographic details, CL experience, and patient-practitioner communication. Strategies must be explored to increase risk awareness through education because this may lead to better compliance practices.

Uptake and release of polyhexamethylene biguanide (PHMB) from hydrogel and silicone hydrogel contact lenses using a radiolabel methodology

PurposeThe purpose of this study was to evaluate the uptake and release of radiolabelled polyhexamethylene biguanide (PHMB) on reusable daily wear contact lenses (CLs) over 7 days. MethodsThree silicone hydrogel (SH) contact lens materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were examined. In experiment 1 (1-day study), CLs were soaked in 2 mL of phosphate buffered solution (PBS) containing radiolabelled 14C PHMB (1 µg/mL) for 8 h. The release kinetics of 14C PHMB from the CLs was measured at t = 0.25, 0.5, 1, 2, 4, 8, and 24 h in fresh 2 mL PBS. In experiment 2 (7-day study), the CLs were soaked in the 14C PHMB (1 µg/mL) solution for 8 h followed by a 16-hour release in 2 mL PBS. The lens cycle was repeated daily for 7 days. After both experiments, the residual amount of PHMB remaining within the lenses was extracted to determine the total uptake of PHMB. ResultsIn experiment 1, the total uptake of PHMB for etafilcon A was significantly greater than senofilcon A (p = 0.01). There were no significant differences in total uptake of PHMB between other lens materials (p > 0.05). Etafilcon A released more PHMB compared to all other lens types over a 24-hr period (p < 0.001). In experiment 2, all CL materials continued to sorb more PHMB over time (p < 0.001). By day 7, the amount of PHMB sorbed by etafilcon A was significantly greater than senofilcon A (p = 0.02). After day 2, the CH materials released significantly more PHMB than the SH materials (p < 0.01). ConclusionThe CL materials continued to sorb PHMB with no signs of saturation after 7 days. All lens materials released a consistent amount of PHMB each day. Radioactive labelling provides a sensitive method of assessing the uptake and release of PHMB from CL materials.

Modification of Silicone Hydrogel Contact Lenses for the Selective Adsorption of Ofloxacin

It is essential to design multifunctional contact lenses for selective recognition and utilization of the eye drop ofloxacin (OFL). Modified silicone hydrogel (MSL) contact lenses were firstly synthesized via ultraviolet curing by using (hydroxymethyl)methyl aminomethane, polydimethylsiloxane, methacryloxypropyl terminated polydimethylsiloxane, and N,N-dimethylacrylamide as monomers and N-vinyl-2-pyrrolidinone (NVP) as a modifier. The synthesized MSL contact lenses were characterized via Fourier transform infrared spectroscopy, scanning electron microscopy, and contact angle and mechanical property tests. The results showed that compared with silicone hydrogel (SL) contact lenses, the MSL contact lenses had a more porous structure and good swelling and mechanical properties. The molecularly imprinted polymer/ofloxacin-modified silicone hydrogel (MIP/OFL-MSL) contact lenses were firstly synthesized via free radical polymerization, using ofloxacin (OFL) as the template molecule. Moreover, compared with chlorogenic acid and myricetin molecule, the MIP/OFL-MSL contact lenses exhibited an adsorption capacity for OFL that reached 2.86 mg/g. The antibacterial test showed that the MIP/OFL-MSL contact lenses displayed an inhibition ring size of 15.2 mm and 17.8 mm for Staphylococcus aureus and Escherichia coli, respectively.

Comparison of Verofilcon A and Etafilcon A Daily Disposable Contact Lenses: Overall Preference and Other Subjective Endpoints

Purpose: To compare the subjective performance of verofilcon A daily disposable silicone hydrogel contact lenses (CL), with 51% water content at the core and >80% water content at the surface, with that of etafilcon A hydrogel CL, which have a water content of 58%.

A clinical performance comparison of three soft reusable multifocal contact lenses

Purpose: To compare the clinical and subjective performance of three daily wear, reusable soft multifocal silicone hydrogel contact lenses: Asmofilcon A (centre near in the low add and a decentred design in a high add) (Menicon Co., Ltd), Lotrafilcon B (centre near) (Alcon) and Comfilcon A (centre near and centre distance) (CooperVision Inc).

In-market assessment of a toric multifocal monthly replacement silicone hydrogel contact lens

Purpose: A third of toric contact lens (CL) wearers are presbyopic, necessitating toric multifocal (TMF) correction to meet eye care professional (ECP) and wearer demands. A multi-practice, observational assessment was conducted to understand ECP fitting behaviour with TMFCLs and wearer satisfaction.

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

Purpose: A new silicone hydrogel (SiHy) material was designed through surface modification of a cross-linkable bioinspired 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer for long-term ocular performance. The surface properties of this MPC polymer-modified lens were characterized under hydrated condition to reveal its unique surface structure and superior surface properties in lubricity and softness.

Influence of Selected Ophthalmic Fluids on the Wettability and Hydration of Hydrogel and Silicone Hydrogel Contact Lenses-In Vitro Study.

This study attempts to evaluate the effect of incubation in selected ophthalmic fluids on contact lenses (Etafilcon A, Omafilcon A, Narafilcon A, Senofilcon A). Four research groups differing in the incubation environment were created: (1) initial state, (2) contact lens solution (CLS), (3) contact lens solution and eye drops (ED) and (4) eye drops. Dehydration by gravimetric method and the contact angle (CA) by the sessile drop method were tested. The surface free energy (SFE) was also calculated with the use of several methods: Owens–Wendt, Wu, Neumann, and Neumann–Kwok. The greatest changes in the dehydration profile were observed for contact lenses incubated in ED. The most noticeable changes in CA values were observed for contact lenses incubated in ED, in which it was not possible to settle water drop after incubation. On the basis of SFE analysis, higher values were found for hydrogel contact lenses, e.g., according to the Owens–Wendt method, they ranged from 54.45 ± 6.56 mJ/m to 58.09 ± 4.86 mJ/m, while in the case of silicone-hydrogel contact lenses, they ranged from 32.86 ± 3.47 mJ/m to 35.33 ± 6.56 mJ/m. Incubation in all tested environments decreased the SFE values, but the differences were in most cases statistically insignificant. Calculating the SFE may be a useful method as it can be used to estimate the possibility of bacteria adhering to contact lens surfaces.

Ефективність контактної корекції гіперметропії в дітей шкільного віку у віддалені терміни спостереження

Актуальність. Окуляри та контактна корекція добре переносяться дітьми при аметропії слабкого та середнього ступеня. При аметропії високого ступеня поліпшення монокулярної гостроти зору з контактною лінзою порівняно з корекцією окулярами вище в 3,8 раза. Матеріали та методи. Під спостереженням перебували 56 дітей (112 очей) віком від 6 до 16 років із гіперметропічною рефракцією та астигматизмом, у яких використовували м’які силікон-гідрогелеві контактні лінзи для корекції аметропії. У цих пацієнтів було проведено дослідження гостроти зору, показників об’єктивної та суб’єктивної клінічної рефракції, аксіальної довжини ока, товщини та діаметра рогівки, показників кератометрії, а також форометричних даних (акомодація, вергенція, диспаратні ділянки окорухового апарату та їх взаємодія) в ранні та пізні строки спостереження. Результати. При застосуванні контактної корекції у дітей шкільного віку з гіперметропією та гіперметропічним астигматизмом статистично значуще через 3 роки спостережень спостерігалося підвищення некоригованої гостроти зору на 85 % (t = 7,9; p &lt; 0,01), коригованої гостроту зору — на 7 % (t = 7,4; p &lt; 0,01), показника кератометрії у слабкому меридіані — на 1 % (t = 6,1; p &lt; 0,01), на 1 % (t = 8,9; p &lt; 0,01) — у сильному меридіані, товщини рогівки у центральній зоні — на 4 % (t = 4,6; p &lt; 0,01), а також зменшення показника сфероеквівалента на 38 % (t = 3,1; p &lt; 0,01), амплітуди акомодації — на 20 % (t = 5,8; p &lt; 0,01), негативної частини відносної акомодації — на 20 % (t = 3,0; p &lt; 0,01), позитивної частина відносної акомодації — на 18 % (t = 3,5; p &lt; 0,01), надлишку акомодаційної відповіді — на 64 % (t = 7,2; p &lt; 0,01), форії вдалину — на 33 % (t = 4,4; p &lt; 0,01), форії зблизька — на 22 % (t = 2,8; p &lt; 0,01), відношення акомодаціоної конвергенції до акомодації — на 18 % (t = 3,1; p &lt; 0,01).

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.

Development of an enzymatic method for the evaluation of protein deposition on contact lenses

The aim of this study was to evaluate a new digestion method to quantify protein deposition on contact lenses. Four silicone hydrogel and one hydrogel contact lens material were incubated in lactoferrin, lysozyme, immunoglobulin A, and bovine serum albumin solutions at approximate physiological concentrations and temperature. Immobilized trypsin was used to digest the protein deposits from the contact lens surfaces. The total protein absorbed to lenses was extracted and digested using sequencing grade trypsin. The tryptic peptides were quantified using selected reaction monitoring mass spectrometry. The concentration of surface protein deposits was either lower than or the same as the total protein for all lens types and proteins. Immobilised trypsin can digest protein deposits from the surface of contact lenses. This ability to analyse the amount of protein at a contact lens surface may help in elucidating the effect of surface deposition on clinical outcomes during lens wear.

3D printed contact lenses for the management of color blindness

Color blindness or color vision deficiency (CVD), a congenital ocular disorder, affects one in 12 males and one in 200 females. CVD currently has no cure; hence, patients opt for wearables that could enhance their color perception such as color filtering glasses and lenses. Herein, we report 3D printing of contact lenses for color blindness management. We utilized an in situ synthesized poly(2-hydroxyethyl methacrylate) (pHEMA) resin and wavelength selective filtering dyes. 3D printing has advantages as compared to conventional techniques due to its ease of manufacturing and high dimensional accuracy, making it a suitable platform for the fabrication of customized contact lenses for colorblindness. Moreover, to filter out the undesired wavelengths, two dyes (i.e., Atto 565 and 488) were utilized to functionalize in the contact lenses. These dyes have absorption bands in the range of 550–580 and 480–500 nm wavelength. The tinted contact lenses successfully blocked 80–90% of the undesired wavelengths, where CVD patients find difficulties in distinguishing shades of certain colors. Furthermore, no dye leakage was observed from the 3D printed hydrogel contact lenses. The fabricated contact lenses were further characterized by optical and physicochemical methods. Contact lenses were tested on colorblind patients using Ishihara test, and evident enhancements in the color perception of the participants were obtained.

Efficacy of fitting HydroCone (Toris K) contact lenses for the visual rehabilitation of patients with posterior microphthalmos.

To evaluate the efficacy of soft HydroCone silicone hydrogel contact lenses in patients with posterior microphthalmos. The charts of 13 patients with posterior microphthalmos (26 eyes) who were fitted with soft HydroCone silicone hydrogel contact lenses were reviewed retrospectively. All the patients underwent assessments of uncorrected and best spectacle-corrected visual acuity and cycloplegic refraction. They were fitted with contact lenses according to the parameter values obtained from the topographical analysis and best contact lens-corrected visual acuity measurement. The spherical equivalents of the right and left eyes ranged from 10.00 to 19.25 diopters and from 11.00 to 21.5 diopters, respectively. The mean axial and posterior chamber lengths were shorter than those of the age-matched population. However, the mean values of the anterior segment parameters such as horizontal visible iris diameter, central anterior chamber depth, lens thickness, and central corneal thickness were in the normal range. The mean keratometric measurements revealed increased corneal curvature compared with that in the normal population. The mean best contact lens-corrected visual acuity was significantly higher than the mean best spectacle-corrected visual acuity for both eyes (p=0.045). HydroCone silicon soft contact lenses provided better visual acuity than spectacles in the patients with posterior microphthalmos in this study.

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.

Zwitterion-Functionalized Hydrogel Contact Lenses for Reducing Protein and Bacteria Adsorption

Zwitterion-Functionalized Hydrogel Contact Lenses for Reducing Protein and Bacteria Adsorption

In vitro and in vivo evaluation of cyclosporine-graphene oxide laden hydrogel contact lenses

Drug-eluting contact lens can substitute the multiple eye drop therapy. However, loading hydrophobic drug like cyclosporine in the contact lens is very challenging, due to low drug uptake (via soaking method); and alteration in the swelling and optical properties which restricts its clinical application. To address the above issues, graphene oxide (GO, large surface area with oxygen containing functional groups) was incorporated in the contact lenses during fabrication. These GO-laden contact lenses (SM-GO-Cys) as well as blank contact lenses (SM-Cys) were soaked in the solution of cyclosporine. Alternatively, cyclosporine-laden contact lenses (DL-Cys-20) and cyclosporine-GO-laden contact lenses (DL-Cys-20-GO) were fabricated by adding drug and drug-GO (at various level of GO) during fabrication, respectively. Contact angle and swelling data showed increase in water holding capacity of GO laden contact lenses. Optical property was significantly improved due to molecular dispersion of drug on the surface of GO sheets. The drug uptake and in vitro release profile was improved with GO-laden contact lenses by soaking method (SM-GO-Cys-400n) due to hydrophobic interactions between GO and drug. Adding cyclosporine-GO (DL-Cys-20-GO-800n) during fabrication significantly improved drug release kinetics with higher drug leaching (during extraction and sterilization) due to increased swelling, improved dissolution and molecular dispersion of drug on GO sheets. Ocular irritation and histopathological studies demonstrated the safety of GO-contact lens. The in vivo drug release studies in the rabbit eye showed significant improvement in mean residence time (MRT) and area under the curve (AUC) using DL-Cys-20-GO-800n contact lens compared to eye drop solution with reduction in protein adherence value. The study demonstrated that the incorporation of GO into the contact lens can control the release of cyclosporine as well as improved the lens swelling and transmittance properties.

Controlled Release of Multiple Therapeutics From Silicone Hydrogel Contact Lenses for Post-Cataract/Post-Refractive Surgery and Uveitis Treatment.

PurposeThis work demonstrates seven-day controlled and extended in vitro physiological flow dual release of multiple post-ocular surgery therapeutics from extended-wear contact lenses as a dropless alternative for treatment of uveitis and corneal inflammation, pain, and infection. Lens replacement each week optimizes treatment matching patient recall time with the ability to increase or decrease dosage.MethodsLenses were synthesized using molecular imprinting to create lenses with macromolecular memory for diclofenac sodium (DS) and dexamethasone sodium phosphate (DMSP), as well as bromfenac sodium (BS) and moxifloxacin (MOX). Drug uptake and release were analyzed, and physical properties were measured and compared to commercial standards.ResultsDS + DMSP–loaded lenses demonstrated seven-days-plus release of each, whereas controls released more than 85% of their payload within the first day. Lenses loaded with BS + MOX demonstrated release of BS and MOX for 11 and eight days, respectively. Structural analysis demonstrated statistically similar mesh size and average molecular weight between crosslinks between imprinted lenses and controls, suggesting that release extension was due to formation of macromolecular memory sites rather than a tighter polymer architecture.ConclusionsLenses demonstrated in this work have significant clinical applications as an eye drop alternative, possessing the ability to be worn continuously for one week while delivering a consistent amount of therapeutic for the duration of wear.Translational RelevanceIn vitro physiological flow release results demonstrate the clinical potential of therapeutic contact lenses as a dropless vehicle for ocular drug delivery.

Nanoscaled Morphology and Mechanical Properties of a Biomimetic Polymer Surface on a Silicone Hydrogel Contact Lens.

Materials taking advantage of the characteristics of biological tissues are strongly sought after in medical science and bioscience. On the natural corneal tissue surface, the highly soft and lubricated surface is maintained by composite structures composed of hydrophilic biomolecules and substrates. To mimic this structure, the surface of a silicone hydrogel contact lens was modified with a biomimetic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), and the nanoscaled morphology and mechanical properties of the surface were confirmed with advanced surface characterization and imaging techniques under an aqueous medium. Concavities and convexities on the nanometer order were recognized on the surface. The surface was completely covered with a PMPC layer and remained intact even after 30 days of clinical use in a human ocular environment. The mechanical properties of the natural corneal tissue and the PMPC-modified surface were similar in the living environment, that is, low modulus and frictional properties comparable to natural tissues. These results show the validity of material preparation by biomimetic methods. The methodologies developed in this study may contribute to future development of human-friendly medical devices.

Review of 20 years of soft contact lens wearer ocular physiology data

BackgroundSince the introduction of Silicone hydrogel (SiHy) contact lenses 20 years ago, industry has continued to modify lens materials, designs, lens care products and manufacturing processes, striving to improve contact lens physiological performance, comfort, and convenience for wearers. The purpose of this study was to investigate whether the ocular health of habitual soft contact lens wearers today is better than it was in previous decades. MethodsBaseline ocular physiology data for 3624 participants from a The Brien Holden Vision Institute clinical trials database were retrospectively reviewed. Records were grouped into 3 time periods; A: >2 decades ago (1997–1999), B: one decade ago (2009–2014) and C: recent years (since 2015). Physiology data for both neophytes and habitual contact lens wearers included; bulbar, limbal and upper palpebral conjunctival redness, corneal and conjunctival staining and conjunctival indentation from contact lenses. ResultsCorneal staining levels are similar between neophytes and contact lens wearers at time points A and C but worse for contact lens wearers at time point B. Limbal redness was greater in contact lens wearers than in neophytes at time point A but at time points B and C they are not different to the non-contact lens wearing population. In recent years, most ocular physiological variables in habitual contact lens wearers are similar to neophytes. ConclusionsWhile there have been changes over the past two decades in ocular physiological responses to contact lens wear, it appears that ocular health with current day contact lens wear is similar to no lens wear in most respects.