Lipid Analysis on Block Copolymer-containing Packaging Solution and Lens Care Regimens: A Randomized Clinical Trial.

SIGNIFICANCE: Lotrafilcon B lenses packaged in and cared for with block copolymer-containing (polyoxyethylene-polyoxybutylene; EOBO) lens care solutions resulted in lower cholesterol extraction than each of the habitual silicone hydrogel lens/multipurpose solution (MPS) regimens tested. PURPOSE: This study aimed to compare the extracted cholesterol of lotrafilcon B lenses packaged in and cared for with EOBO-containing lens care solutions with the extracted cholesterol of habitual silicone hydrogel lenses cared for with MPS not containing EOBO. METHODS: In this prospective, randomized, observer-masked parallel study, habitual wearers of senofilcon C, senofilcon A, comfilcon A, and samfilcon A contact lenses using a non-EOBO MPS were randomized 1:1 to lotrafilcon B lenses packaged in and cared for with EOBO-containing solutions or to their habitual lenses and MPS. Subjects randomized to lotrafilcon B were further randomized to one of two EOBO-containing lens care solutions, OPTI-FREE PUREMOIST or CLEAR CARE PLUS with HydraGlyde (Alcon Laboratories, Inc., Fort Worth, TX). A subset of right eye lenses was collected after wear, and total cholesterol was extracted and measured using a fluorometric enzymatic assay. RESULTS: Of 143 lenses analyzed, 95 were from subjects randomized to their habitual lenses/MPS and 48 to lotrafilcon B + EOBO lenses plus CLEAR CARE PLUS with HydraGlyde or OPTI-FREE PUREMOIST. The mean amounts of cholesterol extracted from lotrafilcon B + EOBO lenses cared for with CLEAR CARE PLUS with HydraGlyde (0.28 ± 0.18 µg/lens) and OPTI-FREE PUREMOIST (0.28 ± 0.48 µg/lens) were significantly lower than those extracted from senofilcon C (4.18 ± 3.25 µg/lens), senofilcon A (2.19 ± 2.69 µg/lens), comfilcon A (2.17 ± 1.47 µg/lens), and samfilcon A (2.07 ± 1.48 µg/lens) lenses used with MPS (P < .0001 each). CONCLUSIONS: Cholesterol sorption was significantly lower in wearers of lotrafilcon B lenses cared for with polyoxyethylene-polyoxybutylene-containing lens care solutions than in users of habitual silicone hydrogel lenses cared for with non-polyoxyethylene-polyoxybutylene MPS.

Preparation, Characterization, and Evaluation of Zinc Oxide Nanoparticles Suspension as an Antimicrobial Media for Daily Use Soft Contact Lenses.

PURPOSE: Infection and inflammation during wearing contact lenses are the problems for the users of daily soft contact lenses. All Gram-positive bacteria, Gram-negative bacteria, and fungi play a role in this problem. In past decades, nanoparticles have largely been studied and shown good antimicrobial activity against various microorganisms. The present study aimed to prepare, characterize, and evaluate zinc oxide nanoparticles (ZNPs) as antimicrobial agents against different microorganisms. MATERIALS AND METHODS: The ZNPs were synthesized in a special structure using the sol-gel process and characterized by XRD, TEM, and EDX. Antimicrobial properties of ZNPs suspension were investigated against different microorganisms (i.e., Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Escherichia coli, and Candida albicans) by the Scanning Electron Microscopy of lens surfaces and pour plate method of immersed lens suspension for microbial enumeration. RESULTS: The XRD, TEM, and EDX spectrum showed hexagonal structure and no impurity in the nanoparticles with a size of about 20 to 40 nanometers. Sterilized suspension of ZNPs was applied against bacterial species, and the results indicated 4 logarithms (CFU/mL) microbial growth reduction for most Gram-positive and Gram-negative species, except for Pseudomonas aeruginosa that showed 3.5 logarithms (CFU/mL) growth reduction. Furthermore, 1 and 1.7 logarithms (CFU/mL) growth reduction were observed for Candida albicans, applying 250 and 500 ppm ZNPs suspension, respectively, which is an acceptable result for fungal growth inhibition. Findings of this study indicated that the suspensions of ZNPs with 250 and 500 ppm showed acceptable bacteriostatic and bactericidal effects. CONCLUSIONS: In vitro antimicrobial activity showed that the suspension of ZNPs with 250 ppm concentration could effectively cause a proper reduction and inhibition in the growth of both Gram-positive and Gram-negative microorganisms. Therefore, the results revealed the efficacy of the antibacterial properties of synthesized ZNPs suspension in aqueous media. ABBREVIATIONS: ZNPs: Zinc oxide nanoparticles; XRD: X-ray diffraction; FWHM: Full width at half maximum; TEM: Transmission electron microscope; SEM: Scanning electron microscope; EDX: Energy-dispersive X-ray spectroscopy; S. aureus: Staphylococcus aureus; S. epidermidis: Staphylococcus epidermidis; L. monocytogenes: Listeria monocytogenes; B. subtilis: Bacillus subtilis; P. aeruginosa: Pseudomonas aeruginosa; S. typhi: Salmonella typhi; E. coli: Escherichia coli; C. albicans: Candida albicans; MK: Microbial keratitis; CLARE: Contact lens-induced acute red eye; CLPU: Contact lens-induced peripheral ulceration; IK: Infiltrative keratitis; AIK: Asymptomatic infiltrative keratitis; MIC: Minimum inhibitory concentration; MBC: Minimum bactericidal concentration; BHI: Brain heart infusion; TSB: Tryptic soy broth; BHIA: Brain heart infusion agar; TSA: Tryptone soya agar.

Sonochemical synthesis of gum guar biopolymer stabilized copper oxide on exfoliated graphite: Application for enhanced electrochemical detection of H2O2 in milk and pharmaceutical samples.

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H2O2 than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H2O2 in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H2O2. Consequently, the fabricated sensor can be used for the accurate detection of H2O2 in real samples.

A water-soluble silver(I) formulation as an effective disinfectant of contact lenses cases.

The antibacterial effect of the already known water-soluble compound {[Ag6(µ3-Hmna)4(µ3-mna)2]2-·[(Et3NH)+]2·(DMSO)2·(H2O)} (AGMNA) (H2mna = 2­mercapto­nicotinic acid) was evaluated by the mean of the Minimum Inhibitory Concentration (MIC), the Minimum Bactericidal Concentration (MBC) and the Inhibitory Zone (IZ), against the bacterial strains Pseudomonas aeruginosa (PAO1) and Staphylococcus aureus (St. aureus) which settle in the cornea, in bacterial keratitis. The MICs' of AGMNA against PAO1 and St. aureus were 25.7 ±â€¯2.4 µM and 42.0 ±â€¯0.3 µM respectively. Τhe Biofilm Elimination Concentration (ΒΕC) was used to evaluate the influence of AGMNA on the formation of biofilm of PAO1. AGMNA exhibits stronger antimicrobial activity than that of H2mna or AgNO3. The toxicity of AGMNA was examined against normal human corneal epithelial cells (HCET cells) and by micronucleus (MN) assay in HCET cells. Thus, the IC50 value of AGMNA, towards HCET cells is higher than 120 µΜ, while its effect on MN frequency, of HCET cells, is meaningless, when they are treated with it at 120 µΜ, suggesting no in vitro genotoxicity. The Mitotic Index (MI), Chromosomal Aberrations (CA) and Nuclear Abnormalities (NA) analyses of Allium cepa reveal insignificant variations between treated and untreated ones indicating no in vivo genotoxicity.

The characteristics of a preservative-free contact lens care solution on lysozyme adsorption and interfacial friction behavior.

The population of soft contact lens wearers is increasing, thus the issues of feeling comfortable and contact lens-induced clinical symptoms are concerned. Both lysozyme deposition and mechanical friction among contact lens and the eye can induce discomfort and eye conditions. Therefore, we characterized our developed preservative-free contact lens care solution on lysozyme adsorption and lubrication. Two distinct lens materials were washed with the care solution after being soaked in lysozyme, as well as were rubbed against the glass in the presence of lysozyme and the care solution for measuring the friction coefficient. Our results demonstrated that the preservative-free contact lens care solution can be applied as a potential lubricant for a specific type of soft contact lenses.

Contact Lens Solutions and Contact Lens Discomfort: Examining the Correlations Between Solution Components, Keratitis, and Contact Lens Discomfort.

OBJECTIVES: This article will examine the current literature, as it relates to contact lens discomfort (CLD) secondary to contact lens solutions. The reader will better understand the characteristics of contact lenses, as they uniquely interact with each type of contact lens solution and also gain a better comprehension of the components of contact lens solution such as preservatives, surfactants, and chelating agents, which may contribute to discomfort. By investigating corneal staining theory and the mechanisms that contribute to its presence, the reader will gain insight into this clinical finding, which relates to selection of contact lens solutions. The FDA standards for testing solutions and how this relates to contact lens keratitis will also be appraised in regards to current ISO recommendations. Finally, better selection of multipurpose contact lens solution (MPS) and hydrogen peroxide-based solutions for patients should be accessible to the clinician based on this review and preexisting clinical findings or diagnoses. METHODS: A review of current published literature from peer reviewed journals and online journals was conducted to gain an understanding of contact lens solution's impact on contact lens discomfort. CONCLUSIONS: Many studies have been conducted comparing comfort between various types of contact lens solutions. It is challenging to decipher this information and apply it clinically when selecting solutions for patients. By comparing solution components, how contact lens solutions interact with different types of lenses, keratitis related to contact lenses, and preexisting ocular conditions, this review will improve a clinician's ability to eliminate CLD.

Cellular fluorescein hyperfluorescence is dynamin-dependent and increased by Tetronic 1107 treatment.

Sodium fluorescein ('fluorescein') staining of the ocular surface is frequently an indicator of compromised ocular health, and increases in the presence of certain contact lens multi-purpose solutions (MPS), a phenomenon known as solution induced corneal staining (SICS). The mechanism(s) underpinning fluorescein hyperfluorescence are uncertain, though may reflect increased cellular uptake of fluorescein by corneal epithelial cells. We have developed an in vitro model to study fluorescein uptake in both 'generic' mammalian cells (murine fibroblasts) and human corneal cells. Fluorescein hyperfluorescence increased after treatment with two MPS associated with clinical corneal fluorescein staining, yet there was no cellular hyperfluorescence for two MPS that do not cause this staining. Increased fluorescein uptake did not correlate with presence of a necrotic or an apoptotic marker (propidium iodide and caspase-3 respectively). Incubation of MPS-treated cells with dynasore (an inhibitor of dynamin, implicated in endocytic pathways) reduced fluorescein uptake irrespective of MPS treatment. The non-ionic surfactant Tetronic 1107 (present in both MPS associated with corneal fluorescein staining) increased uptake of fluorescein for both cell types, whereas an unrelated surfactant (Triton X-100) did not. We conclude that the clinical hyperfluorescence profile observed after exposure to four MPS can be reproduced using a simple model of cellular fluorescein uptake, suggesting this is the biological basis for SICS. Fluorescein entry does not correlate with necrosis or apoptosis, but instead involves a dynamin-dependent active process. Moreover the surfactant Tetronic 1107 appears to be a key MPS constituent triggering increased fluorescein entry, and may be the major factor responsible for SICS.

Consequences of Preservative Uptake and Release by Contact Lenses.

OBJECTIVES: To assess contact lens preservative uptake and release from multipurpose solutions (MPS) and subsequent acquisition of lens antibacterial activity. METHODS: Kinetics of uptake and release of poly (hexamethylene biguanide hydrochloride) (PHMB) or polyquaternium-1 (PQ-1) from various contact lenses were studied initially with the pure compounds and then after soaking in MPS containing these compounds. Lenses soaked in MPS were tested for antibacterial activity. RESULTS: Only lenses with a negatively charged component absorbed these preservatives. For lenses containing methacrylic acid (MA), uptake of PHMB from preservative-only solution was fast, yet little was released, in contrast to its rapid release from lenses containing other anionic groups. This trend persisted with PHMB-containing MPS. PQ-1 from preservative-only solution was only absorbed by lenses containing MA and was released from MA-containing hydrogels, but not significantly from an MA-containing silicone hydrogel. Lens uptake of PQ-1 was much lower from MPS and release was essentially undetectable from all lenses evaluated. Antibacterial lens activity was acquired by lenses containing MA after an overnight soak in MPS containing PQ-1, and for balafilcon A and omafilcon A after 5 exchanges in PHMB-containing MPS. Acquired activity was maintained during cycling between artificial tear protein solution and MPS. CONCLUSIONS: Lens preservative uptake and its subsequent release are dependent on lens chemistry, preservative nature, and other MPS components. A few lens/solution combinations acquired antibacterial activity after one or more overnight soaks in MPS, depending on the nature of the anionic lens component and the preservative. Uncharged lenses did not acquire antibacterial activity.

Role of fatty acid salts as anti Acanthamoeba agents for disinfecting contact lens.

　Acanthamoeba is found in seawater, fresh water, and soil and is an opportunistic pathogen that causes a potentially blinding corneal infection known as Acanthamoeba keratitis. The anti-amoeba activity of 9 fatty acid salts (potassium butyrate (C4K), caproate (C6K), caprylate (C8K), caprate (C10K), laurate (C12K), myristate (C14K), oleate (C18:1K), linoleate (C18:2K), and linolenate (C18:3K)) was tested on Acanthamoeba castellanii ATCC 30010 (trophozoites and cysts). Fatty acid salts (350 mM and pH 10.5) were prepared by mixing fatty acids with the appropriate amount of KOH. C8K, C10K, and C12K showed growth reduction of 4 log-units (99.99% suppression) in A. castellanii upon 180 min incubation at 175 mM, whereas the pH-adjusted control solution showed no effect. After the amoeba suspension was mixed with C10K or C12K, cell membrane destruction was observed. The minimum inhibitory concentration of C10K and C12K was also determined to be 2.7 mM. Confirmation tests were conducted using contact lenses to evaluate the effectiveness of C10K and C12K as multi-purpose solutions. Experiments using increasing concentrations showed reduced numbers of living cells in C10K (5.5 mM, 10.9 mM) and in C12K (5.5 mM, 10.9 mM). These results demonstrate the inhibitory activity of C10K and C12K against A. castellanii and indicate their potential as anti-amoeba agents.

Status of the effectiveness of contact lens disinfectants in Malaysia against keratitis-causing pathogens.

The aim of this study was (i) to assess the antimicrobial effects of contact lens disinfecting solutions marketed in Malaysia against common bacterial eye pathogens and as well as eye parasite, Acanthamoeba castellanii, and (ii) to determine whether targeting cyst wall would improve the efficacy of contact lens disinfectants. Using ISO 14729 Stand-Alone Test for disinfecting solutions, bactericidal and amoebicidal assays of six different contact lens solutions including Oxysept®, AO SEPT PLUS, OPTI-FREE® pure moist®, Renu® fresh™, FreshKon® CLEAR and COMPLETE RevitaLens™ were performed using Manufacturers Minimum recommended disinfection time (MRDT). The efficacy of contact lens solutions was determined against keratitis-causing microbes, namely: Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, and Acanthamoeba castellanii. In addition, using chlorhexidine as an antiamoebic compound and cellulase enzyme to disrupt cyst wall structure, we determined whether combination of both agents can enhance efficacy of marketed contact lens disinfectants against A. castellanii trophozoites and cysts, in vitro. The results revealed that all contact lens disinfectants tested showed potent bactericidal effects exhibiting 100% kill against all bacterial species tested. In contrast, none of the contact lens disinfectants had potent effects against Acanthamoeba cysts viability. When tested against trophozoites, two disinfectants, Oxysept Multipurpose and AO-sept Multipurpose showed partial amoebicidal effects. Using chlorhexidine as an antiamoebic compound and cellulase enzyme to disrupt cyst wall structure, the findings revealed that combination of both agents in contact lens disinfectants abolished viability of A. castellanii cysts and trophozoites. Given the inefficacy of contact lens disinfectants tested in this study, these findings present a significant concern to public health. These findings revealed that targeting cyst wall by using cyst wall degrading molecules in contact lens disinfecting solutions will enhance their efficacy against this devastating eye infection.

Variation of clearance considering viscosity of the solution used in the reservoir and following scleral lens wear over time.

PURPOSE: This study aims to evaluate the settling of a scleral lens and if this process is influenced by the nature of the fluid layer. METHODS: A prospective, non-randomized control study was performed using an 18mm scleral lens. They were fitted with a central clearance of 400 um at insertion. One eye was randomly assigned to be fitted with a non-preserved gel solution of carboxymethylcellulose, while the other was inserted with non-preserved saline. Measurements of clearance in 3 locations were taken (OCT) at baseline, every 30min up to 1h30 post insertion and every 2h thereafter up to 6h00 of wear. A two-way repeated measure analysis of variance (liquids×times) was used to test central, nasal and temporal fluid thickness. RESULTS: Following 6h of wear, the 18mm lens had a mean central settling of 70.0±9.8µm, 36.7±9.8µm of which occurred within the first 30min of wear. There was no significant difference between lenses filled with non-preserved saline to those with non-preserved gel. However, a paired comparison concluded to a significant difference between mean nasal settling (41.4µm) and temporal settling (20.4µm). CONCLUSION: With respect to the lens studied, current results suggest that practitioners can evaluate the lens 30min post insertion and can estimate the amount of fluid that will remain after lens stabilization by doubling the value obtained initially. The use of non-preserved saline or non-preserved more viscous solution to fill the lens does not influence its settling.

Care System Versus Transmitted Light Wavefront Pattern of Contact Lenses.

OBJECTIVES: This article compares the optical performance of soft contact lenses (CLs) treated with multipurpose or hydrogen peroxide care systems. METHODS: The investigated care systems were (1) 3% hydrogen peroxide solution Oxysept (Abbot Medical Optics, Abbott Park, IL) and (2) multipurpose solution Regard (Vita Research, Ariccia, Italy). Three types of silicone hydrogel CLs were studied (comfilcon A, lotrafilcon B, and balafilcon A), unworn and exposed for 30 times to the solutions, which were replaced every 8 hr. The optical performance of the CLs was evaluated through the on-eye transmitted light wavefront patterns by considering new CLs as references. The surface morphology of the CLs was investigated by scanning electron microscopy. RESULTS: Statistically significant modifications in the range 0.1 to 0.3 µm of Zernicke coefficients and modifications of the root mean square of the wavefront aberration function were found for CLs treated with multipurpose solution, in agreement with the observed modifications of the surface morphology. Statistically significant changes were also found after exposure to the hydrogen peroxide solution, but the variation of the Zernicke coefficients was found lower than 0.1 µm, thus being negligible in CL optical performances. CONCLUSIONS: In addition to disinfection ability and ocular surface reactions, CL care systems are different in solution-related CL optical performance. Multipurpose solutions may affect the CL surface morphology with significant modifications of the transmitted light wavefront pattern.

The impact of lens care solutions on corneal epithelial changes during daily silicone hydrogel contact lens wear as measured by in vivo confocal microscopy.

PURPOSE: To assess corneal epithelial microstructure via confocal microscopy and determine if cellular changes are associated with lens care solutions during daily wear of silicone hydrogel contact lenses. METHODS: Corneal in vivo confocal microscopy with the Nidek ConfoScan4 was performed at baseline and after 5 months of lotrafilcon A daily contact lens wear. Enrolled participants were randomized to use either a polyhexamethylene biguanide (PHMB) preserved multipurpose care solution (MPS) or a peroxide based solution system. Lens and storage case bioburden were assessed with aerobic culture methods. Univariate and multivariable analyses were done to evaluate the association between solution use, or solution-related clinical covariates, and morphologic differences (hyper-reflectivity) in the superficial epithelial cells and epithelial basal cell density. RESULTS: Data on 139 participants were available for analysis of superficial epithelial cells while data on 92 participants were available for epithelial basal cell density. Five months after randomization to the solution groups, 33% of participants had visible hyper-reflective cells. More participants using MPS had ≥1 hyper-reflective cells compared to peroxide users at 5 months (44% vs. 22%; p=0.006). Similarly at 5 months, more participants with solution-induced corneal staining (SICS) had ≥1 hyper-reflective cells compared to non-SICS participants (57% vs. 29%; p=0.010). The adjusted odds ratios (ORs) for risk of presenting with hyper-reflective cells in MPS users or SICS participants was 2.7 (95% CI; 1.27-5.65) and 3.4 (95% CI; 1.29-8.97), respectively. Basal cell density decreased by over 350 cells/mm2 over time (about 6%) in participants who had substantial bioburden on their lenses or in their storage case. CONCLUSION: The confocal microscope can detect epithelial cellular changes in vivo during contact lens wear. Hyper-reflective superficial epithelial cells are associated with a PHMB preserved solution and decreases in basal epithelial cell density may be associated with bacterial bioburden.

Effect of multipurpose solutions on in vivo surface wettability of a silicone hydrogel lens.

PURPOSE: To compare the in vivo surface wettability of silicone hydrogel (SiHy) contact lenses pre-soaked overnight in different multipurpose solutions (MPS) and normal saline. METHODS: In this double-blinded, randomized and self-controlled study, 36 subjects were fitted with three pairs of contact lenses (senofilcon A) pre-soaked overnight in five different MPS and saline in a randomized order. Each pair of lenses (pre-soaked in two different solutions the night before) were worn for 15min before assessment of pre-lens non-invasive tear break-up time (PL-NITBUT) using the Medmont corneal topographer (video recording). Corneal integrity was assessed using a slit lamp and a resting interval of 20min was allowed between each pair of lenses to ensure post-lens wear corneal integrity. RESULTS: Thirty subjects completed the study. The median PL-NITBUT ranged from 2.84s to 3.08s with lenses pre-soaked in different MPS, compared to 2.78s with lenses pre-soaked in saline. No significant differences in PL-NITBUT were found among lenses pre-soaked in different solutions (p=0.647). CONCLUSION: In vivo surface wettability, in terms of PL-NITBUT after 15min of lens wear, of senofilcon A contact lenses pre-soaked overnight in different MPS were not significantly different from those pre-soaked in saline.

The use of dimethyl sulfoxide in contact lens disinfectants is a potential preventative strategy against contracting Acanthamoeba keratitis.

Acanthamoeba castellanii is the causative agent of blinding keratitis. Though reported in non-contact lens wearers, it is most frequently associated with improper use of contact lens. For contact lens wearers, amoebae attachment to the lens is a critical first step, followed by amoebae binding to the corneal epithelial cells during extended lens wear. Acanthamoeba attachment to surfaces (biological or inert) and migration is an active process and occurs during the trophozoite stage. Thus retaining amoebae in the cyst stage (dormant form) offers an added preventative measure in impeding parasite traversal from the contact lens onto the cornea. Here, we showed that as low as 3% DMSO, abolished A. castellanii excystation. Based on the findings, it is proposed that DMSO should be included in the contact lens disinfectants as an added preventative strategy against contracting Acanthamoeba keratitis.

Effect of the osmolarity change in multipurpose solutions induced by an improper contact lens case cleaning procedure.

PURPOSE: To determine whether variations in multipurpose disinfecting solution (MPDS) storage osmolarity from inappropriate contact lens (CL) case cleaning affect ocular surface integrity and wearer comfort. METHODS: There were twenty contact lens cases (study CLCs) in the study group. Ten were filled with ReNu Multiplus(®) and 10 with SoloCare Aqua™ (MPDS-1 and -2, respectively) and kept closed for 8h; the cases were then emptied and kept open for air-drying for 16h. This procedure was carried out every day for two months. Storage solution osmolarity was measured on days 0, 15, 30, 45 and 60. Ten subjects were then fitted with both month-old lenses stored in the study CLCs and with new lenses stored in new cases with fresh solution for 24h (control CLCs). Symptoms, tear osmolarity and percentage of subjects whose conjunctival hyperaemia and ocular surface staining scores changed were determined after 1h of wear. RESULTS: Study CLC osmolarity increased in both solutions after two months (p<0.05). For MPDS-1 there were differences in stinging between study CLCs and control CLCs after 10min of CL wear (p=0.04), and in comfort after 10 (p=0.035) and 60min wear (p=0.042). Significant (p<0.05) differences between study CLC and control CLC groups were also found for MPDS-2 in limbal hyperaemia (study: 50% change; control: 0% change) and bulbar and corneal staining (study: 80% change; control: 20% change). CONCLUSION: The stored-MPDS osmolarity increase caused by air-drying the CLCs could affect the ocular surface. This increase might reduce lens wear comfort.

Accuracy of a Freezing Point Depression Technique Osmometer.

PURPOSE: The purpose of this study was to examine the precision and accuracy of the Fiske 110 Osmolarity System under different protocols to determine the possible applications of this device in tear film research and clinical practice. METHODS: Three separate studies were performed. In the first, Fiske 110 measurements were made on undiluted and diluted (1:1, 1:4, and 1:9 dilutions) standard samples of different osmolarity values: 50, 290, and 850 mOsm/kg and 297 and 338 mOsm/L. In the second study, measurements were made on different types of contact lens care solutions. Finally, in an agreement study, measurements were made in two sets of 60 subjects to compare TearLab versus Fiske 110 (using both 2- and 4-µL tear sample). RESULTS: Although osmolarity measurements for undiluted solutions differed statistically from reference standard values, all biases were in the tolerance range proposed by the manufacturer except for the 850-mOsm/kg solution. No significant differences from reference osmolarity values were observed for the 1:1 and 1:4 diluted 297- and 338-mOsm/L H2O solutions, respectively, although all diluted solutions showed a possible bias out of the range provided. Osmolarities for the soft contact lens solutions fell within the range 293 to 309 mOsm/kg with the exception of Opti-Free Express (225 mOsm/kg). In the agreement study, significant differences were observed between measurements obtained using the TearLab and both Fiske 110 procedures, although the Fiske 110 (4 µL) procedure was closer to the TearLab than the Fiske (2 µL) procedure. CONCLUSIONS: For undiluted solutions, the Fiske 110 shows good performance, making it a useful device for osmolarity measurements in lens care solutions or eye drops. A worse performance was observed for more diluted standard solution samples. When testing diluted samples, performance was acceptable for osmolarity values close to tear values.

Performance of three multipurpose disinfecting solutions with a silicone hydrogel contact lens.

PURPOSE: To evaluate the clinical performance of a silicone hydrogel (Si-Hy) soft contact lens (CL) in combination with three different multipurpose disinfecting solutions (MPDSs). METHODS: This was a prospective, randomized, single-masked, crossover, and comparative study in which 31 habitual soft CL wearers were randomly assigned to one of the three MPDSs (Synergi, COMPLETE RevitaLens, and OPTI-FREE PureMoist) for 1 month with a 1-week wash-out period between each exposure. All subjects were successfully refitted with a Si-Hy CL (Biofinity). Subjects were then scheduled for follow-up visits after 1 month of lens wear, being evaluated at 2 and 8 hours after lens insertion. Visual Analogue Scales (VAS) were used to gauge comfort rating. RESULTS: The tarsal conjunctiva showed a significantly different degree of lid redness between the MPDSs at the 2-hour visit (P < 0.05, Kruskal-Wallis test), being lower for COMPLETE RevitaLens compared to the other two MPDSs (Mann-Whitney U test). Furthermore, a significantly different degree of lid roughness at the 8-hour visit was seen (P < 0.05, Kruskal-Wallis test), being higher for Synergi (Mann-Whitney U test). The subjective comfort was similar with the three MPDSs. CONCLUSION: Tarsal conjunctival response should be also considered in the context of the clinical performance of MPDs at the ocular surface.

Extended elution of phospholipid from silicone hydrogel contact lenses.

Characterization of phospholipid release from an experimental reusable wear silicone hydrogel contact lens was performed to assess the possible use of these lenses for phospholipid delivery to increase eye comfort to patients who prefer reusable wear lenses. Contact lenses were loaded with 200 µg of radio-labeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) from a solution of n-propanol. To simulate 30 days of diurnal use with overnight cleaning, these lenses were eluted for 16 h at 35 °C into artificial tear fluid (ATF), and then eluted at room temperature (~22 °C) for 8 h in one of three commercial contact lens cleaning systems. This was repeated for 30 days. The elution of DMPC into ATF was greater on the first day, followed by a fairly constant amount of elution each day thereafter. The type of cleaning system had a statistically significant effect on the elution rate during daily exposure to ATF. The rate of elution into cleaning solutions did not show any enhanced elution on the first day; there was a fairly constant elution rate. Again, the type of cleaning system significantly influenced the elution rate into the nightly cleaner.

The role of multi-purpose solutions in prevention and removal of lipid depositions on contact lenses.

The sorption and desorption of radiolabeled dipalmitoylphosphatidylcholine (DPPC) and cholesterol (CH) were measured on 5 types of commercial contact lenses. The lenses were soaked in vitro in an artificial tear fluid for 16h. The effects of borate buffered saline and two commercial multi-purpose lens-care solutions (MPSs) on reducing the lipid (DPPC and CH) sorption and increasing the lipid removal were examined. The results showed that silicone hydrogel (SiHy) lenses accumulated the most lipids, sorbing over an order of magnitude more than polymacon, a conventional hydrogel lens. Pre-soaking the SiHy lenses for 16h in MPSs reduced the DPPC sorption by up to 13% and the CH sorption by up to 11%, compared to controls that were not pre-soaked. However neither these reductions nor those on polymacon were statistically significant (p>0.05). In sorption experiments without presoaking, subsequent exposure to the MPSs removed some DPPC from the lenses (0-3.1% for SiHy lenses and 14-55% for polymacon), but CH removal was 0.0-0.8% for SiHy lenses and 0.6-28% for polymacon lenses. Some of these removals were statistically significant (p<0.05).