Artificial Tear Solution Research Articles

Simple and effective: Superlubricity behaviour of the G-quadruplex hydrogel with high selectivity for K+ ions based on the ocular environment

Hydrogels have been the subject of significant research in the field of friction due to their exceptional lubricating properties. In this study, the G-quadruplex hydrogel with high selectivity for K+ ions was formed by introducing a mixture of G, 2-formylphenylboronic acid, and polyethylene glycol diamine into simulated artificial tears solution with high transparency, and an ultra-low coefficient of friction (COF) of about 0.004 was obtained based on the simulated ocular environment, thus achieving macroscopic superlubricity. In friction pairs simulating the ocular environment, to assess the frictional performance of the G-quadruplex hydrogel as both a lubricant and a friction pair based on the simulated ocular environment, we conducted experiments considering various factors such as concentration, sliding speed, and stress. Through these experiments, it was found that superlubricity was achieved when the G-quadruplex hydrogel was applied as lubricant or friction pair. This effect was attributed to the three-dimensional network structure and hydrophilicity of the hydrogel, which facilitated the formation of a highly bearing and flowing hydration layer, promoting macroscopic superlubricity. Compared to the G-quadruplex hydrogel with low concentration, the high concentration hydrogel (75 mM) exhibited increased mechanical strength and robustness in superlubricity. Combined with biocompatibility experiments, our synthesized G-quadruplex hydrogel has excellent biocompatibility and offers a novel approach to achieve superlubricity in ocular drug delivery.

Carrageenan films as promising mucoadhesive ocular drug delivery systems

Polymer mucoadhesive films being developed for use in ophthalmology represent a new tool for drug delivery and are considered an alternative to traditional dosage forms. Due to their mucoadhesive properties, carrageenans (CRGs) are widely used in various forms for drug delivery. In this study, films based on CRGs of various structural types (κ/β, κ, x, and λ) for use in ophthalmology were studied. The films were loaded with the active substance echinochrome (ECH), a sea urchin pigment used in ophthalmology. Spectral data showed that ECH remained stable after its incorporation into the CRG films and did not oxidize for at least six months. Hydrophilic CRG films with a thickness of 10−12 µm were characterized in terms of their swelling and mucoadhesive properties. The rheological properties of solutions formed after film dissolution in artificial tears were also assessed. κ- and κ/β-CRG films with ECH exhibited pseudoplastic behavior after rehydrating films with an artificial tear solution. The CRG-loaded films had different swelling characteristics depending on the structure of the CRG used. The films based on highly sulfated CRGs dissolved in artificial tears, while the films of low-sulfated κ/β-CRG exhibited limited swelling. All studied ECH-loaded films exhibited mucoadhesive properties, which were evaluated by a texture analyzer using mucous tissue of the small intestine of the pig as a model. There was a slight prolongation of ECH release from CRG films in artificial tears. The effect of CRG/ECH on the epithelial cell lines of the outer shell of the human eye was investigated. At low concentrations, ECH in the composition of the CRG/ECH complex had no cytotoxic effect on corneal epithelial and conjunctival human cells. The use of ECH-containing films can prevent the drug from being immediately washed away by tears and help to retain it by increasing viscosity and having mucoadhesive properties.

Comparative evaluation of the intravenous effect of medetomidine, tramadol and medetomidine/tramadol combination on tear production in clinically healthy donkeys (Equus asinus)

Various ophthalmic disorders (conjunctivitis, corneal wounds, keratitis) have been reported in donkeys. There are no studies on the effect of medetomidine or tramadol on Schirmer tear test (STT) readings in donkeys. This prospective study investigated changes in STT readings in 24 clinically healthy donkeys (Equus asinus) (14 geldings and 10 mares) treated with commonly used doses of medetomidine hydrochloride and tramadol hydrochloride as mono- or combined therapy. Analgesia, sedation, ataxia, and STT readings were measured before treatment (baseline) and at different periods after administration (5–120 min) of the specific drug in each group. Tramadol monotherapy induced a mild analgesic effect (score 1) at 10 min post-administration. All treated donkeys exhibited mild to moderate ataxia. Medetomidine alone or in combination with tramadol induced a significant decrease (P<0.05) in the STT readings in both right and left eyes at 5, 15, 30, and 60 min relative to baseline, and the lowest values were observed 60 min after drug administration in both groups. Intravenous administration of medetomidine alone or in combination with tramadol induced a significant reduction in STT readings in clinically healthy donkeys. Therefore, in donkeys, the ocular surface treated with these sedatives should be carefully examined and adequately covered by an artificial tear solution or ophthalmic gel.

Impact of in vitro lens deposition and removal on bacterial adhesion to orthokeratology contact lenses

PurposeThe purpose of this study was to explore the impact of several contact lens (CL) care solutions on the removal of proteins and lipids, and how deposit removal impacts bacterial adhesion and solution disinfection. MethodsLysozyme and lipid deposition on three ortho-k (rigid) and two soft CL materials were evaluated using an ELISA kit and gas chromatography respectively. Bacterial adhesion to a fluorosilicone acrylate material using Pseudomonas aeruginosa with various compositions of artificial tear solutions (ATS), including with denatured proteins, was also investigated. The impact of deposition of the different formulations of ATS on biofilm formation was explored using cover slips. Finally, the lysozyme and lipid cleaning efficacy and disinfection efficacy against P. aeruginosa and Staphylococcus aureus of four different contact lens care solutions were studied using qualitative analysis. ResultsWhile maximum lysozyme deposition was observed with the fluorosilicone acrylate material (327.25 ± 54.25 µg/lens), the highest amount of lipid deposition was recorded with a fluoro-siloxanyl styrene material (134.71 ± 19.87 µg/lens). Adhesion of P. aeruginosa to fluorosilicone acrylate lenses and biofilm formation on cover slips were significantly greater with the addition of denatured proteins and lipids. Of the four contact lens care solutions investigated, the solution based on povidone-iodine removed both denatured lysozyme and lipid deposits and could effectively disinfect against P. aeruginosa and S. aureus when contaminated with denatured proteins and lipids. In contrast, the peroxide-based solution was able to inhibit P. aeruginosa growth only, while the two multipurpose solutions were unable to disinfect lenses contaminated with denatured proteins and lipids. ConclusionBacterial adhesion and biofilm formation is influenced by components within artificial tear solutions depositing on lenses, including denatured proteins and lipids, which also affects disinfection. The ability of different solutions to remove these deposits should be considered when selecting systems to clean and disinfect ortho-k lenses.

Comprehensive Analysis of Drug Loading into Engineered Lipoprotein Nanoparticles toward Their Eye Drop Application.

The drug loading capacity of an engineered lipoprotein (eLP1) and the colloidal stability of drug-loaded eLP1s were assessed with 12 drugs with different charges/hydrophobicities. The capacity was largely correlated with their log P values, and the binding to the protein moiety was suggested for two drugs. The size of drug-loaded eLP1 formulations after freeze-drying followed by resolubilization hardly changed. The eLP1 formulation of travoprost, a clinically used drug in eye drop formulations, maintained its small size (19 nm) for 1 h at 37 °C in an artificial tear solution, whereas the liposome counterpart of 112 nm in diameter aggregated.

Tear-based MMP-9 detection: A rapid antigen test for ocular inflammatory disorders using vanadium disulfide nanowires assisted chemi-resistive biosensor

A sensitive, non-invasive, and biomarker detection in tear fluids for inflammation in potentially blinding eye diseases could be of great significance as a rapid diagnostic tool for quick clinical decisions. In this work, we propose a tear-based MMP-9 antigen testing platform using hydrothermally synthesized vanadium disulfide nanowires. Also, various factors contributing to baseline drifts of the chemiresistive sensor including nanowire coverage on the interdigitated microelectrode of the sensor, sensor response duration, and effect of MMP-9 protein in different matrix solutions were identified. The drifts on the sensor baseline due to nanowire coverage on the sensor were corrected using substrate thermal treatment providing a more uniform distribution of nanowires on the electrode which brought the baseline drift to 18% (coefficient of variations, CV = 18%). This biosensor exhibited sub-femto level limits of detection (LODs) of 0.1344 fg/mL (0.4933 fmoL/l) and 0.2746 fg/mL (1.008 fmoL/l) in 10 mM phosphate buffer saline (PBS) and artificial tear solution, respectively. For a practical tear MMP-9 detection, the proposed biosensor response was validated with multiplex ELISA using tear samples from five healthy controls which showed excellent precision. This label-free and non-invasive platform can serve as an efficient diagnostic tool for the early detection and monitoring of various ocular inflammatory diseases.

A tear-based battery charged by biofuel for smart contact lenses

Smart contact lenses developed for medical and personal applications will require miniaturized power supplies, with integrated batteries providing promising options. However, charging batteries in small wearable devices is challenging because it is difficult to transfer electrical power through a miniaturized wired connection or wireless transmission unit. Herein, we develop safe, tear-based batteries integrated into contact lenses that are charged by biofuel during their storage. Enzymatic reactions of glucose oxidase and self-reduction of conducting polymer are utilized to charge the cathode and anode, respectively. The electrodes are embedded into a contact lens and discharged in an artificial tear solution followed by charging in a glucose solution via a bio-reaction (called bio-charging). The bio-charging battery shows a discharging capacity of 45 μA cm−2 and a maximum power of 201 μW cm−2, with its performance verified over 15 cycles. The bio-chargeable battery can also be charged conventionally by an external power supply.

Precorneal retention time of ocular lubricants measured with fluorophotometry in healthy dogs.

Determine the precorneal retention time of five different ocular lubricants commonly used in dogs. Six healthy Beagle dogs (n=12 eyes). Five ocular lubricants were studied: Artificial Tears Solution® (1.4% polyvinyl alcohol), I-Drop® Vet Plus (0.25% hyaluronate), Optixcare® Eye Lube Plus (0.25% hyaluronate), Systane® Ultra (0.4% polyethylene glycol 400 and 0.3% propylene glycol), and Artificial Tears Ointment® (mineral oil/white petrolatum). Each lubricant was mixed with 10% sodium fluorescein to achieve 1% fluorescein formulations. Following topical administration of 35 mg in each eye, tear fluid was collected with capillary tubes at selected times (0, 1, 5, 10, 20, 30, 40, 50, 60, 90, 120, 180 min) and fluorescein concentrations were measured with a computerized scanning ocular fluorophotometer. Tear fluorescence was significantly greater with Artificial Tears Ointment® compared with other lubricant formulations from 1 to 20 min post-administration. Median (range) precorneal retention times were significantly different among the 5 lubricants, ranging from 40 minutes (20-90 min) for Artificial Tears Ointment®, 35 min (20-90 min) for Systane® Ultra, 30 min (10-60 min) for I-Drop® Vet Plus, 25 min (10-60 min) for Optixcare® Eye Lube Plus, and 10 min (10-20 min) for Artificial Tears Solution®. Precorneal retention time was significantly lower for Artificial Tears Solution® compared with the other 4 formulations. This study established normative data for the retention time of common lubricants on the ocular surface of dogs, which may be used to guide clinicians with their choice of lubricant and frequency of administration.

Modern trends in tear replacement therapy for patients with dry eye syndrome

Today, the dry eye syndrome therapy is based on the techniques aimed at compensating for loss of moisture in the conjunctival cavity (the so-called tear replacement therapy) either by additional moistening of the eye surface, or by maintaining the moisture in the conjunctival cavity. Traditionally, the first step is to moisturise the eye surface, and the artificial tear products is the leader in this area. In recent years, natural mucopolysaccharides are one of the basic components of artificial tears that attract the greatest practical interest, and among them is the hyaluronic acid, or rather its sodium salt, which is almost identical in pharmacological properties to native hyaluronic acid with the respective molecular weight. Hyaluronic acid is characterized by high mucoadhesiveness, which allows the artificial tear solution based on this polymer to bind to mucins on the eye surface and prolong the residence time of the formulation on the ocular surface. The even more significant property of high molecular-weight HyA is the so-called thixotropy: the high molecular-weight HyA has a high viscosity on the open eye, which provides good wettability of the ocular surface. Today, preservative-free solutions based on the hyaluronic acid sodium salt, which are characterized by high thixotropy, hygroscopicity, mucoadhesiveness and good tolerability, are the priority. The high effectiveness of such drugs has been established. They provide deep hydration in the treatment of dry eye syndrome due to Sjögren's syndrome, meibomian blepharitis and perimenopause, as well as dry eye syndrome in children. The latter was developed due to neuroparalytic keratitis, chronic blepharitis, and systematic damage to the ocular surface by eye drops containing preservatives.

The Effect of Polysaccharides on Preventing Proteins and Cholesterol from Being Adsorbed on the Surface of Orthokeratology Lenses.

The adsorption of tear film compositions such as proteins and lipids on the orthokeratology lenses often lead to infection or corneal damage. In order to investigate whether polysaccharides could prevent tear compositions from being adsorbed on the lens, alginic acid and lambda-carrageenan were added into artificial tear solution. By measuring daily adsorption of cholesterol, lysozyme, and albumin, our results showed that polysaccharides could weakly prevent cholesterol adsorption. In addition, polysaccharides could also reduce albumin deposition over time. Although the effect of polysaccharides on lysozyme adsorption was distinct depending on the concentrations of polysaccharides, the overall results demonstrated that polysaccharides could decrease protein deposition over time. Our results provided an in vitro evidence that polysaccharides may be applied as coating materials on the lens or as the composition of artificial tear solutions or eyedrops, in order to prevent adsorption of tear film compositions that may lead to a reduced incidence of infection or corneal damage for orthokeratology lens wearers.

Solution-related in Vitro Dewetting Behavior of Various Daily Disposable Contact Lenses.

SIGNIFICANCEThe dewetting process of contact lenses (CLs) is a result of material and solution properties as well as environmental factors. This article describes an investigational approach to observe and describe dewetting characteristics of different CL material and solution combinations.PURPOSEThis study aimed to determine the in vitro dewetting characteristics of various daily disposable CLs that were assessed using a noninvasive keratograph dewetting procedure (noninvasive keratograph dry-up time). In vitro dewetting data of the same CL materials soaked in saline solution and artificial tear solution (ATS) were measured to determine additional dewetting characteristics.METHODSNoninvasive keratograph dry-up time was measured for six different soft CL materials and three different test conditions, in their specific blister solution, after exposure to saline and an ATS. Twenty CLs of each solution/material combination were assessed after an 8-hour soaking, during a 180-second dewetting observation, and the results were expressed by area under the curve values.RESULTSFastest dewetting occurred for all materials when measured out of saline, indicated by the highest averaged area under the curve value of 9243.3 ± 38.3 over all lens materials. Slower dewetting was detected for all materials when measured out of their specific blister solution (7755.9 ± 37.1) and out of ATS (7988.8 ± 40.0). Intragroup results were statistically significantly different for all solutions showing the smallest differences within the ATS group (P < .001, Kruskal-Wallis test).CONCLUSIONSA pure saline thin film is not an ideal representation of a complex tear film layer of a healthy human because it lacks any evaporative protection by a lipid layer. The use of an ATS, which more likely mimics the natural tear film, allowed in this experimental in vitro project to decrease the gap to the in vivo field. In vitro dewetting information in connection with the blister solution allows only a theoretical conclusion about the initial lens wear after lens insertion.

Study of the effect of dynamic viscosity on the performance of a portable microinjector for severe dry eye treatment using a glycerol-water mixture as a test fluid.

This article presents the experimental results of a series of performance tests performed on a microinjector designed to deliver different artificial tear solutions to patients with severe dry eye syndrome. The device is intended to aid in the treatment of this syndrome by providing a continuous injection of artificial tears as needed that overcomes many of the deficiencies inherent in dripping from the manual method. In this work, a set of experiments were carried out to quantify the temporal error that allow determining the dynamic behavior of the viscosity of the glycerol/water mixture as a suitable test solution for the device and then comparing it with the use of commercial artificial tears to define an acceptable viscosity range with a lower temporal error for the correct operation of the system. The experimental method of viscosity measurement was used by means of an Ostwald viscometer that allows determining the times that flow the volume of various percentages by volume of glycerol/water and drops. In addition, the gravimetric density method was used to determine the density and subsequently by the Poiseuille relationship with respect to the densities of percentages in volume of glycerol/water and drops, the different times that flow through a capillary tube, the dynamic viscosity. The results obtained during the operation of the tested microinjector suggest that the microinjector can function correctly without problem in a range of evaluated dynamic viscosity of 1 to 1500 mP a.s with a maximum temporal error of ∼ 5 %. The temporal error evaluated is a parameter that is necessary to know for the well-being of patients using this device and the viscosities of the products used do not significantly influence the performance of the microinjector.

Femtosecond Laser Ablation Assisted NFC Antenna Fabrication for Smart Contact Lenses

AbstractSmart contact lenses (SCLs) have drawn substantial interest for continuous health monitoring applications. Even though most of the reported works utilize near‐field communication (NFC) or inductive coupling for wireless powering and data transmission, developing a scalable and rapid fabrication technique for annular ring antennas confined in a small contact lens area is still an unsolved challenge. Here, femtosecond laser ablation is employed for the first time as a simple, single‐step, and highly precise fabrication technique for NFC antennas using conventional flexible printed circuit board materials. Antenna lines with depth and width of 9 and 35 μm are achieved, respectively. The antenna with a footprint of 19.5 mm2 is characterized in biological solution followed by aging, and bending tests, and a frequency deviation of less than %1 is recorded. A real‐life application is demonstrated by fabricating an SCL embedded with the antenna, an NFC chip, and an electrochemical sensor for wireless monitoring of glucose in artificial tear solution by a smartphone. The device could successfully quantify biologically relevant glucose concentrations ranging from 0.2 to 1 mM with a limit‐of‐detection of 66 μM. In addition, device response to interfering molecules is less than ±1 nA, and the spike‐and‐recovery test is successfully demonstrated.

The effect of tamarind seed polysaccharidecontaining eye drop in dry eye syndrome: Results of an interventional, comparative, clinical study

Background: The mainstay of dry eye treatment is artificial tear solutions. Contralateral eye comparison of 2 types of artificial tears (Xiloial versus Tearlose) in managing dry eye disease was sought in this study.&#x0D; Methods: This study was a prospective, interventional, contralateral eye comparison of 2 types of artificial tears used for managing dry eye disease. The study participants were categorized into mild (13–22 points), moderate (23–32 points), or severe (33–100 points) ocular surface disease according to the baseline ocular surface disease index (OSDI) questionnaire score. Schirmer I and tear film break-up time (TBUT) tests, as well as detailed slit-lamp examinations, were performed at baseline and at the end of the study. All participants received Xiloial monodose eye drops for the right eye and Tearlose eye drops for the left eye, administered as a single drop 4 times per day. Furthermore, they were instructed to perform lid hygiene every 12 hours per day for both eyes.&#x0D; Results: Thirty-five patients (70 eyes) with a mean ± standard (SD) age of 50.2 ± 13.4 years were included, and 14 (40%) were men. The mean ± SD of the OSDI score was 44.24 ± 22.59 at baseline. Of the 35 patients, 10 (28.6%), 5 (14.3%), and 20 (57.1%) had mild, moderate, and severe ocular surface disease, respectively, according to the baseline OSDI score. Compared to baseline, the mean values of both TBUT and Schirmer I tests improved significantly in both groups (both P &lt; 0.001). In comparing the final mean values between the 2 groups, this improvement was comparable for the Schirmer I test (P = 0.179), but TBUT in Tearlose-instilled eyes improved significantly more than in the fellow eyes (P &lt; 0.001).&#x0D; Conclusions: Both Xiloial and Tearlose eye drops improved tear stability and tear production after a 2 week treatment period in eyes with dry eye disease. This improvement was comparable for tear production, but Tearlose-instilled eyes showed significantly greater improvement in tear stability. Further studies with longer follow-up and larger sample sizes could provide more reliable results as a basis for the clinical use of this TSP-containing lubricant eye drop solution in dry eye disease.

Effects of Temperature and Blinking on Contact Lens Dehydration of Contemporary Soft Lens Materials Using an In Vitro Blink Model.

PurposeThe purpose of this study was to evaluate the effects of temperature and blinking on contact lens (CL) dehydration using an in vitro blink model.MethodsThree silicone hydrogel (delefilcon A, senofilcon A, and comfilcon A) and two conventional hydrogel (etafilcon A and omafilcon A) CL materials were evaluated at 1 and 16 hours. The water content (WC) of the CLs was measured using a gravimetric method. Lenses were incubated on a blink model, internally heated to achieve a clinically relevant surface temperature of 35°C. An artificial tear solution (ATS) was delivered to the blink model at 4.5 µL/min with a blink rate of 6 blinks/min. A comparison set of lenses were incubated in a vial containing either 2 mL of ATS or phosphate-buffered saline (PBS) at 35°C.ResultsIncreasing temperature to 35°C resulted in a decrease in WC for all tested CLs over time (P ≤ 0.0052). For most CLs, there was no significant difference in WC over time between ATS or PBS in the vial (P > 0.05). With the vial system, WC decreased and plateaued over time. However, on the blink model, for most CLs, the WC significantly decreased after 1 hour but returned toward initial WC levels after 16 hours (P > 0.05).ConclusionsThe reduction in WC of CLs on the eye is likely due to both an increase in temperature and dehydration from air exposure and blinking.Translational RelevanceThis study showed that the novel, heated, in vitro blink model could be used to provide clinical insights into CL dehydration on the eye.

(Invited) Lactate Fueled Wearable Power Suppliers: From Enzymatic Biofuel Cell to Biosupercapacitor and Photobiobattery

Nowadays, growing research in wearable biosensors for personal healthcare spurs the interest in flexible and miniaturized power suppliers. Enzymatic biofuel cells (EBFCs) [1] utilize oxidoreductases as catalysts, allowing to generate electricity from the chemical energy in sugars. Lactate exists in tear or sweat with a relatively high concentration, which can be the fuel for EBFC. Those applications require flexible, biocompatible and high-surface-area electrodes. Nanoporous gold (NPG) can be an excellent candidate meeting all the requirements [2]. We fabricate a mechanically stable and flexible NPG by electrochemically dealloying Au/Ag alloy films that are sputtered on plastic membranes [3]. The NPG has been biofunctionalized for EBFC applications. Flexible NPG based lactate/O2 EBFCs on commercial contact lenses register 1.7 ± 0.1 μW cm-2 in air-equilibrated artificial tear solutions, which is slightly lower than those obtained in PBS (2.4 ± 0.2 μW cm-2) [3]. A quasi-solid-state and flexible EBFC can be skin-worn consuming the stocking fuel in a hydrogel electrolyte, avoiding the constrain of the required sweat sugars [4]. The device can also function as a self-powered biosupercapacitor delivering pulses for over 600 cycles, with a power density over 10 times higher than that from the EBFC alone.The combination of bioelectrodes and photoelectrode leads to a new-type photobiobattery. We will also describe a lactate/O2 photobiobattery using a dioxygen-reducing biocathode and a lactate-oxidising photocatalysts on the anode.

Lysozyme Deposition on Contact Lenses in an In Vitro Blink-Simulation Eye Model Versus a Static Vial Deposition Model.

To evaluate active lysozyme deposition on daily disposable (DD) contact lenses (CL) using a novel in vitro blink model. Three conventional hydrogel DD CL materials (etafilcon A, omafilcon A, nelfilcon A) and three silicone hydrogel DD CL materials (delefilcon A, senofilcon A, somofilcon A) were tested. The device blink rate was set to 6 blinks/min with a tear flow rate of 1 μL/min using an artificial tear solution (ATS) containing lysozyme and other typical tear film components. After incubation at 2, 4, or 8 hr, lenses were removed, and lysozyme activity was measured. A separate experiment was conducted with lenses incubated in a static vial containing 480 μL of ATS. Etafilcon A deposited significantly higher amounts of active lysozyme (402±102 μg/lens) than other lens materials after 8 hr (P<0.0001). Etafilcon A had a higher amount of active lysozyme using the blink model compared with the static vial (P=0.0435), whereas somofilcon A (P=0.0076) and senofilcon A (P=0.0019) had a higher amount of lysozyme activity in the vial compared with the blink model. The blink model can be tuned to provide quantitative data that closely mimics ex vivo studies and can be used to model deposition of lysozyme on CL materials.

The Impact of Incubation Conditions on In Vitro Phosphatidylcholine Deposition on Contact Lens Materials.

Previous in vitro measurements of contact lenses commonly investigate the impact of nonpolar tear film lipids (i.e., sterols). Polar lipids, however, are equally important stabilizing components of the tear film. This research explores and presents further knowledge about various aspects of polar lipid uptake that may impact contact lens performance. This study evaluated the impact of incubation time, lipid concentration, and replenishment of an artificial tear solution (ATS) on the uptake of phosphatidylcholine (PC) onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials. Four SHs and two CH lens materials (n = 4) were soaked in a complex ATS containing radioactive 14C-PC as a probe molecule. Phosphatidylcholine uptake was monitored at various incubation time points (1, 3, 7, 14, and 28 days), with different ATS lipid concentrations (0.5×, 1×, 2×) and with and without regular replenishment of the ATS. Phosphatidylcholine was extracted from the lenses, processed, and counted by a β counter, and accumulated PC (μg/lens) was extrapolated from standard lipid calibration curves. All materials exhibited increasing PC deposition over time. Conventional hydrogel materials showed significantly lower PC uptake rates (P < .001) than any of the SH materials. Increasing lipid concentration in the ATS resulted in increased PC binding onto the contact lens materials (P < .001). Replenishing the ATS every other day, however, impacted the PC deposition differently, showing increased binding (P < .001) on CHs and reduced PC deposition for SH materials (P < .001). Length of incubation, lipid concentration in the ATS, and renewal of the incubation solution all influenced the amount of PC that sorbed onto various lens materials and therefore need to be considered when conducting future in vitro deposition studies.

Solution related in vitro dewetting behavior of different SCL materials

Purpose: In vitro dewetting characteristics of different silicone hydrogel daily disposable contact lenses were measured out of their specific blister solution using Non-Invasive Keratograph Drying-Up Time procedure to determine short-term dewetting characteristics. In vitro dewetting characteristic curves of same CL materials soaked in saline solution (control solution) and artificial tear solution (ATS) were measured to determine additional dewetting characteristics.

Development of a novel hyaluronic acid membrane for the treatment of ocular surface diseases

Ocular surface diseases (OSD) can cause serious visual deterioration and discomfort. Commercial artificial tear solution containing hyaluronic acid (HA) show excellent biocompatibility and unique viscoelastic characteristics. Here, we developed a novel HA membrane (HAM) by chemical crosslinking using 1,4-butanediol diglycidyl ether for the effective treatment of OSDs. The main purpose of HAMs is to provide sustained release of HA to modulate the wound healing response in OSDs. The safety and efficacy of HAMs were investigated using primary cultured human corneal epithelial cells and various OSD rabbit models. In the dry state, the HAM is firm, transparent, and easy to manipulate. When hydrated, it swells rapidly with high water retention and over 90% transmission of visible light. Human corneal epithelial cells and rabbit eyes showed no toxic response to HAM. Addition of HAMs to the culture medium enhanced human corneal epithelial cell viability and expression of cell proliferation markers. Investigation of HAM wound healing efficacy using mechanical or chemical corneal trauma and conjunctival surgery in rabbits revealed that application of HAMs to the ocular surface enhanced healing of corneal epithelium and reduced corneal limbal vascularization, opacity and conjunctival fibrosis. The therapeutic potential of HAMs in various OSDs was successfully demonstrated.