Solo Care Aqua Research Articles

Silver Nanoparticles Conjugated with Contact Lens Solutions May Reduce the Risk of Acanthamoeba Keratitis.

Acanthamoeba keratitis (AK), a severe sight-threatening corneal infection, has become a significant medical problem, especially among contact lens wearers. The disease manifests as eye pain, congestion, blurred vision, lachrymation, and ring-shaped infiltrates of the cornea, and can lead to permanent blindness. Inappropriate habits of contact lens users may result in an increased risk of AK infection. The anti-amoebic efficiency of popular multipurpose contact lens solutions is insufficient to reduce this risk. An effective and non-toxic therapy against AK has not yet been developed. The prevention of AK is crucial to reduce the number of AK infections. Nanoparticles are known to be active agents against bacteria, viruses, and fungi and were also recently tested against protozoa, including Acanthamoeba spp. In our previous studies, we proved the anti-amoebic and anti-adhesive activity of silver nanoparticles against Acanthamoeba castellanii. The aim of this study is to evaluate the activity, cytotoxicity, and anti-adhesive properties of silver nanoparticles conjugated with five commonly used multipurpose contact lens solutions against the Acanthamoeba castellanii NEFF strain. The obtained results show a significant increase in anti-amoebic activity, without increasing the overall cytotoxicity, of Solo Care Aqua and Opti Free conjugated with nanoparticles. The adhesion of Acanthamoeba trophozoites to the contact lens surface is also significantly reduced. We conclude that low concentrations of silver nanoparticles can be used as an ingredient in contact lens solutions to decrease the risk of Acanthamoeba keratitis infection.

In vitro effects of selected contact lens care solutions on Acanthamoeba castellanii strains in Poland

Free-living, cosmopolitan amoebae of the Acanthamoeba genus may be the causative agents of Acanthamoeba keratitis (AK) – a progressive, vision-threatening infection of the human cornea described particularly among contact lens wearers. Use of contact lens care solutions, effective against these organisms, is important in preventing AK infections. 3 different strains of Acanthamoeba castellanii of the T4 genotype (Neff strain and two others, isolated from patients with AK) were exposed to 4 selected multipurpose contact lens care solutions available in Poland: Ciba Vision AoSept Plus, Bausch & Lomb ReNu MultiPlus, Alcon Opti-Free, Ciba Vision Solo Care Aqua. No amoebicidal effect was observed. The strongest amoebostatic effect was visible after 24h of exposition to Opti-Free and ReNu solution and associated with percentage increase of rounded, motionless forms. This is significantly longer than minimum disinfection time recommended by manufacturers of all tested multipurpose solutions. Surprisingly, no clear induction of the encystation process was observed.

Surface roughness and refractive index changes in contact lens induced by lens care systems.

The aim of this study was to analyze the influence of different lens care systems in surface roughness and refractive index (RI) of contact lenses (CL). This information provides us with a better understanding of how care solutions affect CL materials. Several CL and three commercially available and appropriate lens care solutions were used (two polyhexamethylene biguanide and one hydrogen peroxide care systems). Lenses were immersed in the lens care systems, and then measurements with CLR 12-70 digital automated refractometer and atomic force microscopy analysis on Tapping mode were recorded. The measurements were performed before and after the lenses were immersed in each care solution. Significant changes were observed on the CL materials when exposed to lens care systems. All the materials changed, to a greater or lesser extent, their roughness and RI, after being immersed in the different solutions. The water content varied between 0% (Nelfilcon A in ReNu Multiplus, Senofilcon A in AOSEPT Plus, and Methafilcon A in Solocare Aqua) and 4.1% (Hilafilcon B in Solocare Aqua) The higher change in roughness was obtained with ReNu Multiplus in the lens Comfilcon A (with an increase of 27.2 nm) and Senofilcon A (with an increase of 16.7 nm). This study suggests that lens care systems play an important role in surface roughness and RI of CL.

Efficacy of multipurpose contact lens solutions against ESBL-positive Escherichia coli, MRSA, and Candida albicans clinical isolates.

The antimicrobial effects of multipurpose contact lens solutions (MPSs) have been evaluated according to ISO 14729 standards. The aim of this study was to assess the efficacy of commercially available MPSs against extended-spectrum beta lactamases (ESBL)-producing Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans clinical isolates. Three commercially available contact lens solutions (Opti-Free Expresss, ReNu MultiPlus, and Solo Care Aqua) were tested against 18 ESBL-positive E. coli clinical strains, 20 MRSA clinical strains, and 20 C. albicans clinical strains. The stand-alone assays for bacteria and fungi were performed according to ISO 14729 criteria, and all samples were evaluated after 2, 4, and 24 hours of incubation. The numbers of viable microorganisms were evaluated by the plate-counting method. All MPSs demonstrated at least 3 log reduction in colony-forming units (CFU) for all bacterial isolates and 1 log reduction in CFU for all yeast isolates, which meets ISO 14729 standards. Although no statistically significant differences were obtained among MPSs for bacterial isolates, variable responses were observed against clinical isolates: 5% povidone-iodine was more effective compared with Solo Care Aqua for C. albicans clinical strains (P<0.05); and all solutions were effective after an incubation time of only 2 hrs. The MPSs showed good activity against S. aureus, E. coli, and C. albicans. Although effective log reductions were provided with all MPSs, the reduction was variable depending on the strains tested. Multipurpose contact lens solutions should be tested under ISO 14729 standards for both standard and clinical strains.

Cytotoxic and Inflammatory Effects of Contact Lens Multipurpose Solutions on Human Corneal Epithelial Cells

Multipurpose solutions (MPSs) are the leading method for cleaning and disinfecting soft contact lenses (CLs). During recent years, numerous clinical studies have evaluated the MPS damage to the ocular surface. This study examined the cytotoxic and the inflammatory effects of MPSs and hydrogen peroxide disinfection system (H202) compared to appropriate controls on human corneal epithelial (HCE) cells. Primary cultured HCE cells were exposed to eight different commercially available MPS products (MPS A, ReNu MultiPlus®; MPS B, Opti Free® EverMoist; MPS C, Solo-care Aqua®; MPS-D, Complete®; MPS-E, Unica Sensitive®; MPS-F, Options Multi®; MPS-G, Biotrue®; MPS-H, COMPLETE® RevitaLens). Morphological changes and cytotoxic effects were examined with FITC-Annexin V/PI and MTT assays. The protein contents of the inflammatory cytokines interleukin (IL)-1β, TNF-α, IL-6 and IL-8 were examined by multiplex fluorescent bead immunoassay (FBI), and the mRNA expression was examined by real time PCR. Lipopolysaccharide (LPS) with 500 ng/ml CD14 and 500 ng/ml LBP (LPS complex), polyinosinic: polycytidylic acid (Poly I:C) and un-neutralized H202 served as positive controls, respectively. Phosphate-buffered saline (PBS) was added as a negative control. The study demonstrated that most of the MPSs induced varying degrees of cytotoxicity to HCE cells, and increased production of pro-inflammatory cytokines compared to the negative control. In addition, several MPS increased the mRNA level of inhibitory factor-κBα (1-κBα). Among the various MPSs, MPS-H induced the highest protein contents of the pro-inflammatory cytokines (14.37±2.2-fold for TNF-α, 41.39±2.5-fold for IL-1β and 5.24±0.6-fold for IL-6) compared to the negative control (p&lt;0.05). In contrast, no significant differences were noted between the neutralized H202 and the negative control. We conclude that most of the currently used MPSs induce significant damage and inflammatory response in corneal epithelial cells. MPS-induced inflammation was mediated through NF-κB signal transduction. This study demonstrates for the first time inflammatory responses at the molecular level in primary HCE cells following exposure to a large series of commercially available and commonly used MPSs. These findings strongly suggest that certain MPSs may be partially involved in the pathogenesis of contact lens intolerance. Therefore, we recommend that practitioners advise patients as to the preferable disinfecting contact lens solutions, and to consider using the hydrogen peroxide disinfection systems instead.

Antifungal efficacy of soft contact lens disinfecting solutions against Fusarium solani and Candida albicans

Purpose: The aim was to evaluate the disinfection properties of six multi‐purpose contact lens disinfection solutions (MPDS) available in Iran against Fusarium solani and Candida albicans, based on the International Organization for Standardization (ISO) 14729 guidelines.Methods: Three lots each of six multi‐purpose solutions, namely, Renu MultiPlus, Solo Care Aqua, All‐Clean soft, Contact All In One Advanced, Hippia, Ginza Multi‐Purpose Solution and 0.9% normal saline solution were inoculated with standard strains of Fusarium solani (ATCC 36031) and Candida albicans (ATCC 10231). Surviving fungi were determined by counting colony‐forming units on recovery plates at specified times. The mean log reduction in fungal numbers at the manufacturer's minimum recommended disinfection time was determined and compared with the criteria for stand‐alone disinfection products for each MPDS against each fungal strain.Results: Renu MultiPlus, Contact All In One Advanced and All‐Clean Soft were effective in achieving the mean 1.0 log reduction in fungal numbers, based on ISO 14729 stand‐alone primary acceptance criteria. Solo Care Aqua failed to achieve the ISO 14729 stand‐alone primary acceptance criteria for Candida albicans. The other solutions were not effective against test microorganisms after the specified times.Conclusions: There were differences in the rates of disinfection efficacy. Generally, Renu MultiPlus, Contact All In One Advanced and All‐Clean Soft exceeded the primary acceptance criteria of the ISO 14729 guidelines for stand‐alone contact lens solutions.

Contact Lens Case Cleaning Procedures Affect Storage Solution pH and Osmolality

To investigate pH and osmolality changes in the solutions stored in contact lens (CL) cases, when different case rinsing and drying methods are used on a daily basis. Four multipurpose solutions (Opti-Free Express, Solo-Care Aqua, Re-Nu Multiplus, and Complete) and two hydrogen peroxide systems (AOsept and Oxysept) were studied. Cases were filled with the solutions and kept sealed. After 8 h, the cases underwent different rinsing (rinsing; non-rinsing) and drying (air drying-AD; lint-free tissue drying-LFTD; non-drying-ND) procedures on a daily basis. Five cases of each rinsing/drying combination for each solution were evaluated. The pH and osmolality of the case-contained solution were evaluated on the 1st, 7th, 15th, and then, 30th day. pH and osmolality increased significantly from day 1 to 30, except for Complete in which a significant decrease in pH was found. Rinsing vs. non-rinsing CL cases did not have any influence on the pH or osmolality, except for Oxysept, which showed a significantly higher osmolality value when cases were not rinsed. However, the drying procedure did influence both measurements; pH was significantly higher in the AD compared with the ND group (p < 0.05), and there was a significant difference in osmolality between the three drying conditions (p < 0.05), with the AD group showing the highest values, and the LFTD group showing the lowest. Osmolality and pH values are time and drying process-dependent in a CL case cleaning schedule. Regarding drying conditions, LFTD causes less increase in osmolality. Future studies should determine whether these changes might affect bacterial growth, lens parameters, or subject comfort during CL wear.

Contact lens disinfecting solutions antibacterial efficacy: comparison between clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus

To evaluate the disinfectant properties of the three multipurpose contact lens disinfecting solutions available in Iran, against clinical isolates and the standard ISO ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus, based on the international organization for standardization (ISO) 14729 guidelines. Three multipurpose solutions that were tested were ReNu Multiplus, Solo Care Aqua and All-Clean Soft. The test solutions were challenged with clinical isolates and the standard strains of P. aeruginosa(ATCC 9027) and S. aureus(ATCC 6538), based on the ISO Stand-alone procedure for disinfecting products. Solutions were sampled for surviving microorganisms at manufacturer's minimum recommended disinfection time. The number of viable organisms was determined and log reductions calculated. All of the three test solutions in this study provided a reduction greater than the required mean 3.0 logarithmic reduction against the recommended standard ATCC strains of P. aeruginosa and S. aureus. Antibacterial effectiveness of Solo Care Aqua and All-Clean Soft against clinical isolates of P. aeruginosa and S. aureus were acceptable based on ISO 14729 Stand-alone test. ReNu MultiPlus showed a minimum acceptable efficacy against the clinical isolate of S. aureus, but did not reduce the clinical isolate by the same amount. Although the contact lens disinfecting solutions meet/exceed the ISO 14729 Stand-alone primary acceptance criteria for standard strains of P. aeruginosa and S. aureus, their efficacy may be insufficient against clinical isolates of these organisms.

Comparative efficacies of contact lens disinfecting solutions against Pseudomonas aeruginosa

Purpose: The aim of the present study was to evaluate the disinfection properties of multipurpose contact lens disinfection solutions, based on the International Organization for Standardization (ISO) 14729 guidelines.Methods: Three lots of each of six multi‐purpose solutions were tested as follows: Renu MultiPlus, Solo Care Aqua, All‐Clean Soft, Contact All‐in one Advanced, Hippia, Ginza multi‐purpose solution and 0.9% normal saline solution were inoculated with the standard strain of Pseudomonas aeruginosa (ATCC 9027). The surviving bacteria were quantified at specified times. An average logarithm reduction in bacterial numbers at the manufacturer's minimum recommended disinfection time was determined and compared with the criteria for stand‐alone disinfection products for each multi‐purpose disinfection solution against each bacterial strain.Results: Renu MultiPlus, Solo Care, All‐Clean Soft and Contact All‐in one Advanced were effective in achieving a four logarithmic units reduction in the bacterial count; however, Renu MultiPlus and Solo Care Aqua resulted in the greatest reduction in bacterial numbers. The other solutions were not effective against Pseudomonas aeruginosa after specified times.Conclusions: Generally, Renu MultiPlus, Solo Care Aqua, All‐Clean Soft and Contact All‐in one Advanced meet the ISO 14729 guidelines for stand‐alone contact lens solutions.

Ocular tolerance of a new multipurpose solution specifically formulated for daily wear of silicone hydrogel contact lenses

To evaluate the safety, physiological performance, and effect on ocular tissues of a new multipurpose disinfecting solution (MPDS) specifically formulated for use with silicone hydrogel (SH) contact lenses (CL). Two MPDS [solution A (Solo-care Aqua(®), Ciba-Vision) and solution B (Hidro Health(®), Disop)] were randomly assigned and prescribed in a clinical trial in a crossover clinical trial (Registered #293/07/EC; Spanish National Health Department). Only lotrafilcon B CL daily wearers were included. After each solution was used, a masked investigator assessed the slit-lamp findings (SL9, Topcon Inc.), lens deposits, and wettability according to the Guidance for clinical investigation (ISO 11980). CL daily wearing time (hours per day and days per week) were recorded. Fifty-four daily wearers were included. Average CL wear time was 8.3 ± 2.3 (CI95% 7.9-8.7) hours per day (8.5 ± 2.7 at baseline visit, 8.2 ± 1.9 with solution A, and 8.4 ± 2.2 with solution B). The average number of days per week of CL wear was 5.9 ± 1.3 (CI95% 5.6-6.1) (5.4 ± 1.6 at baseline visit, 6.1 ± 0.9 with solution A, and 6.0 ± 1.1 with solution B). Non-adverse slit-lamp findings were recorded (higher than 2 points). No statistical difference (P>0.05 Friedman test) in CL wearing time, number of days of CL wears and slit-lamp findings were found between the two solutions. This clinical trial shows that the new formulation of Hidro Health(®) MPDS is safe when used for the care of daily-wear lotrafilcon B CL. This new solution has no clinical significance on ocular tissues, according to the Guidance for clinical investigation (ISO 11980).

Multipurpose Solutions and Contact Lens: Modulation of Cytotoxicity and Apoptosis on the Ocular Surface

We evaluated (1) 4 multipurpose lens care solutions and 3 contact lenses (soft and rigid) for cytotoxicity according to ISO 10993-5 standard (medical device biocompatibility) and (2) the protective effects of a marine cationic solution and hyaluronic acid. Low water soft lens, high water soft lens, and rigid lens were laid on a conjunctival cell line after being soaked in multipurpose solution (Optifree Express, Renu, Solocare Aqua, or Menicare Plus). Cell morphology was microscopically observed, and cell viability was evaluated using the neutral red test. Apoptosis was assessed after direct contact of multipurpose solutions (MPS) with conjunctival cells using fluorescence microscopy and flow cytometry. The ability of a controlled ionization marine solution and hyaluronic acid to prevent multipurpose solution's cytotoxicity was finally evaluated. Contact lenses soaked in the MPS induced cell morphology alterations and loss of cell viability. Rinsing the lens with the marine solution improved cell viability and preincubating cells with hyaluronic acid inhibited apoptosis. MPS can be damaging for the ocular surface cells. We proposed to rinse the lens with a marine solution before insertion of the lens on the cornea to wash away the multipurpose solution and to use hyaluronic acid to protect the ocular surface cells against apoptosis induced by MPS.

Differences in the Daily Symptoms Associated With the Silicone Hydrogel Contact Lens Wear

To determine the differences in symptoms associated with daily wear of silicone hydrogel (lotrafilcon B) contact lenses (CLs) after CL insertion and at the end of wear and their relationship with environmental factors and multipurpose solutions (Solo-care Aqua, CIBA Vision, Duluth, GA and Hidro Health, Disop, Spain). Fifty-four patients were fitted with lotrafilcon B CLs. Two multipurpose solutions were randomly assigned and prescribed in a double-masked crossover study with three visits. After each solution was used, two questionnaires were conducted, including a survey produced by us and Contact Lens Dry Eye Questionnaire. Our questionnaire included 10 items addressing discomfort, blurry vision, lens-handling problems, dryness, redness, tearing, burning, itching, discharge, and dissatisfaction. Patients were assigned scores from 0 (without symptoms) to 10 (symptoms unbearable) at two different times (after CL insertion and at the end of wear) and in two environments (outdoors and adverse environments). The average duration of CL wear was 8.32 +/- 2.27 hr/day and 5.85 +/- 1.30 days/week. All symptoms became worse (P < 0.05 Wilcoxon test, except lens handling) at the end of CL wear in all visits. The results were independent of the multipurpose solution used (P > 0.05 Friedman test), except for tearing, which showed statistical differences between visits (P = 0.03 Friedman test). Contact Lens Dry Eye Questionnaire showed increased dry eye symptoms at the end of wear (P < 0.05 Friedman test). Daily wear symptoms associated with lotrafilcon B CL increase with the time of wear. This increase in symptoms is nonrelated with the multipurpose solutions compared in this study.

Using a Meta-Analysis to Determine Relationships Between Various Safety Parameters and Lens Care Solutions

Free-living, cosmopolitan amoebae of the Acanthamoeba genus may be the causative agents of Acanthamoeba keratitis (AK) – a progressive, vision-threatening infection of the human cornea described particularly among contact lens wearers. Use of contact lens care solutions, effective against these organisms, is important in preventing AK infections. 3 different strains of Acanthamoeba castellanii of the T4 genotype (Neff strain and two others, isolated from patients with AK) were exposed to 4 selected multipurpose contact lens care solutions available in Poland: Ciba Vision AoSept Plus, Bausch & Lomb ReNu MultiPlus, Alcon Opti-Free, Ciba Vision Solo Care Aqua. No amoebicidal effect was observed. The strongest amoebostatic effect was visible after 24 h of exposition to Opti-Free and ReNu solution and associated with percentage increase of rounded, motionless forms. This is significantly longer than minimum disinfection time recommended by manufacturers of all tested multipurpose solutions. Surprisingly, no clear induction of the encystation process was observed.

Multipurpose Disinfecting Solutions and Their Interactions With a Silicone Hydrogel Lens

To assess the compatibility of a new silicone hydrogel lens, asmofilcon A (with four multipurpose disinfecting solutions: OPTIFREE RepleniSH, ReNu MultiPlus, Solo-Care Aqua and MeniCare Soft). Ocular responses and subjective responses were monitored with each lens-care system combination. The study was conducted as a prospective, bilateral, clinical trial with a single-masked investigator, and randomized cross-over design with four phases, (one for each care system). Each study phase comprised of two consecutive days of lens wear where the lenses were inserted on day 1 directly from the blister-packs and worn for over 8 hr, then inserted on day 2 after overnight disinfection with one of the study lens care systems. Twenty-five adapted soft contact lens wearers who were able to wear their habitual lenses comfortably for more than 12 hr were recruited. There were statistically significant differences in corneal staining found for all the lens-care systems when comparing the results of day 1 (from the blister pack) with day 2 (following care system use) (P < 0.05). ReNu MultiPlus solution had the highest grade for corneal staining at the 2-hr time point on day 2 which then decreased by 6 hr (P < 0.05). There was no difference between the lens care systems and the rating of subjective comfort over either of the two days. The rating of dryness and burning sensations were only slightly increased at 6 hr for all lens care systems except ReNu MultiPlus where burning was highest on insertion (P < 0.05). Corneal staining observed in this study does not seem to have been related to the presence of polyhexamethylene biguanide (0.0001% wv) that was present in three of the four care systems. Only one care system (ReNu MultiPlus) demonstrated an associated level of corneal staining that was statistically significant; however, this was not considered to be of clinical relevance. These results suggest that using this novel surface-treated silicone hydrogel lens may result in less lens and lens care-related interactions.

Physical Properties of Soft Contact Lens Solutions

To investigate the physical properties of commercially available soft contact lens solutions. The pH, osmolality, surface tension (ST), and viscosity of various soft contact lens solutions were measured at room temperature. Viscosity measurements were also taken at 34 degrees C. The solutions examined were Opti-Free Express (OFX), Opti-Free RepleniSH (OFR), Complete Moisture Plus (COM), UltraCare (UC), ReNu MultiPlus, Sensitive Eyes, AOSept (AO), Clear Care, SoloCare Aqua, and SoftWear saline. The peroxide solutions were measured before and after neutralization. The pH of most solutions was close to neutral (range 7.00-7.36), except for OFX and neutralized AO and Clear Care. The osmolality values of most solutions were in the 275 to 310 mOsm/kg range. OFX exhibited a significantly lower osmolality (225 mOsm/kg; p < 0.001), whereas UC was significantly higher (329 mOsm/kg; p < 0.001). Neutralized AO and SoftWear saline had ST values of approximately 67 mN/m. OFX, OFR, and SoloCare Aqua exhibited low ST values in the 30 to 35 mN/m range. The remaining solutions exhibited intermediate ST values of approximately 40 mN/m. These three groupings were significantly different (p < 0.001). The average viscosity of most solutions at room temperature was between 0.95 and 1.26 cP, except for COM (3.02 cP; p < 0.001). At 34 degrees C, the average viscosity of most solutions was between 0.70 and 0.83 cP, except for COM, which had a viscosity of 1.92 cP (p < 0.001). The un-neutralized peroxide solutions had very different pH and osmolality values from all the solutions that would directly contact the eye (p < 0.001). Their viscosity and ST values were similar (p = NS). This study detailed many physical properties of soft lens solutions that are not readily available and indicated that certain properties vary significantly among these products.

Efficacy of contact lens storage solutions against trophozoite and cyst of Acanthamoeba castellanii strain 1BU and their cytotoxic potential on corneal cells

Acanthamoeba is a free-living amoeba causing a potentially blinding infection of the cornea. Contact lens wearers are most at risk and account for about 95% of cases. We investigated the in vitro effectiveness of 10 contact lens solutions against Acanthamoeba castellanii and their cytotoxicity on corneal cells in vitro. Contact lens solutions were evaluated for their amoebicidal activities using an inverted light microscope. To determine of their cytotoxicity on corneal cells, agar diffusion tests were performed. According to the results obtained from the tests, AVIZOR Aqua Soft Comfort and Elegance(R) showed the best amoebicidal effect on A. castellanii trophozoites. Cysts were still viable after overnight (8 h) exposure. In the case of the cyctotoxic acitivities, All In One Light, Astek, SOLO-Care Aqua, Maxima, and Horien showed no cytotoxicity on the corneal cells. ReNu MultiPlus, AVIZOR Aqua Soft Comfort, Carrera, and Elegance showed mild cytotoxicity on the corneal cells. Plurisol.M presented moderate cytotoxicity on the corneal cells. All commercial solutions examined in this study are the lack of efficacy against A. castellanii. Improvement or development of new contact lens disinfecting systems by the manufacturers is needed to prevent Acanthamoeba keratitis.

Clinical and laboratory testing of a silver-impregnated lens case

Purpose Lens case contamination is a well-documented occurrence for contact lens wearers despite the efficacy of current lens disinfectants. Several microorganisms have a propensity to attach to surfaces and may become more tolerant of disinfection upon attachment. Non-compliance with disinfection regimens occasionally occurs wherein patients store their lenses in saline or in tap water. A silver-impregnated lens case was developed in an attempt to decrease case contamination. These studies examine the performance of the case both in vitro and in vivo. Methods In vitro, lens cases were challenged with 10 3 microorganism suspensions of bacteria. After 24 h incubation at room temperature, aliquots of inocula were removed and spread plated onto appropriate growth media. Surviving colonies were counted and microorganism log drop values from initial challenge inocula were determined. Two 40-subject 1-month contralateral clinical studies were conducted with SOLO-care Aqua ® solution using one bowl of a silver-impregnated case and one bowl of a standard lens case for lens storage. Lens cases were collected and cultured for aerobic bacteria. Results In vitro efficacy data show significantly lower numbers of recovered microbes from silver-impregnated cases than from control cases. In both clinical studies, silver-impregnated cases had a statistically significantly lower proportion of bacterial contamination than control cases. The majority of microorganisms isolated from silver-impregnated cases were members of the normal skin flora. Conclusion The performance of the silver-impregnated case in vitro and the observed lower proportion of contaminated silver-impregnated lens cases in a clinical setting demonstrate the case's ability to decrease bacterial contamination.

Cytotoxicity and antimicrobial activity of six multipurpose soft contact lens disinfecting solutions1

To assess and compare the cytotoxicity and antimicrobial activity of six multipurpose disinfecting contact lens solutions (MPDS). Six MPDS were assessed and compared: MeniCare Soft, Complete Moisture Plus, Solo-Care Aqua, Opti-Free Express, ReNu MultiPlus and ReNuMoistureLoc. Cytotoxicity was evaluated by means of the colony-forming assay (ISO 10993-5) using one cell line. One hundred Chinese hamster's fibroblast V79 cells in 2 mL of medium were inoculated into 6-well plates and cultured for 24 h. After incubation, the medium was removed and 2 mL of each MPDS was diluted with physiological saline and medium and added individually into wells at 1.25, 2.5, 5 and 10% concentrations. After an additional 6 days of incubation, cells were fixed and stained with Giemsa solution. Subsequently, the number of colonies was counted. Cytotoxicity was expressed in terms of the concentration of the MPDS that suppresses colony formation. Antimicrobial activity was evaluated by means of the stand-alone contact lens disinfection test (ISO 14729). Cytotoxicity--MeniCare Soft and Complete Moisture Plus were not cytotoxic at any of the concentrations tested. The cytotoxicity ranking of the other MPDS was as follows: Solo-Care Aqua approximately equal to Opti-Free Express < ReNu MultiPlus < ReNu MoistureLoc. Antimicrobial activity--All MPDS met the primary criteria of the stand-alone test for bacterial species. ReNu MoistureLoc showed borderline values for Serratia marcescens and Staphylococcus aureus. Complete Moisture Plus failed to meet the stand-alone test criteria for Fusarium solani. Large differences in cytotoxicity and antimicrobial activity were found among the MPDS under investigation. Multipurpose disinfecting contact lens solutions with identical concentrations of polyhexamethylene biguanide can behave differently depending on solution formulation. The new MeniCare Soft showed effective antimicrobial activity and minimal cytotoxicity.

Efficacy of multipurpose solutions against Acanthamoeba species

Aim The disinfection efficacy of contact lens multipurpose solutions (MPSs) against Acanthamoeba polyphaga (Ros) and Acanthamoeba castellanii (ATCC30868) cysts and trophozoites was determined by both biocidal and manufacturer-recommended no-rub/rinse regimen testing. Methods A biocidal assay using four MPSs (ReNu ® with MoistureLoc ®, Opti-free Express, Solo-care Plus, and Complete MoisturePlus) was conducted with or without the presence of organic soil. A second test procedure compared the ability of five MPSs (ReNu with MoistureLoc MPS, ReNu MultiPlus, Opti-free Express, Solo-care Aqua, and Complete MoisturePlus) to remove and kill Acanthamoeba species cysts and trophozoites from SofLens 38 and Surevue conventional hydrogel lenses, and Focus Night & Day silicone hydrogel lenses using the manufacturer-recommended regimen. Results In the biocidal assay, only ReNu with MoistureLoc successfully killed both trophozoites and cysts (>3 log) within the manufacturer-recommended soak time. A >3 log decrease in trophozoites, but not cysts, was reported for Opti-free Express; however, Solo-care Plus and Complete MoisturePlus did not reduce the number of cysts or trophozoites by >3 log during the manufacturer-recommended soak time. In the no-rub/rinse regimen tests, only ReNu with MoistureLoc removed an inoculum of 2 × 10 5 trophozoites or cysts from SofLens 38 and Surevue hydrogel lenses, as well as Focus Night & Day silicone hydrogel lenses. Less than 10 viable organisms were recovered from the lenses after the 10 s rinse and 4 h soak. Opti-free Express, Solo-care Aqua, and ReNu MultiPlus were effective at removing trophozoites and cysts from SofLens 38 and Surevue conventional hydrogel lenses, but not from Focus Night & Day silicone hydrogel lenses. In excess of 10 viable organisms were recovered from all lenses after the manufacturer-recommended regimen using Complete MoisturePlus. Conclusions These data suggest that some MPSs, when used as recommended by the manufacturer, are more effective at killing representative strains of Acanthamoeba than others.