Multipurpose Contact Lens Solutions Research Articles

Evaluation of in vitro cytotoxicity assays for contact lens multi-purpose solutions

Evaluation of in vitro cytotoxicity assays for contact lens multi-purpose solutions

Potential Resistant Morphotypes of Acanthamoeba castellanii Expressed in Multipurpose Contact Lens Disinfection Systems

The free-living amoeba Acanthamoeba castellanii is a rare cause of contact lens-associated microbial keratitis. The cyst stage of this amoeba is noted for its resistance to disinfection by multipurpose contact lens solutions (MPS). This report examines and reviews the potential survival modes of A. castellanii in MPS. Trophozoites of A. castellanii (ATCC 30234) at densities from 10 to near 10 were incubated in 3 different MPS in a laminar flow hood for 24 hours at ambient temperatures. The dried films of MPS and phosphate-buffered saline (PBS) controls were examined before and after the addition of a peptone-yeast extract-glucose recovery broth (PYG) for the presence of amoeboid trophozoites and resistance stages over at least 7 days. The parallel exposure of trophozoites to MPS without evaporation or addition of PYG was similarly examined. Amoeboid trophozoites were not recovered in PYG nor were cyst-like structures observed in any MPS with near 10 densities. Progressively with 10 to 10 trophozoites, varied survival modes, particularly aggregates of trophozoites associated with cyst-like structures and occasional amoeboid forms and double-walled cysts with ostioles, became more evident. These morphotypes were most prominent after evaporation and typically first observed in the PYG. Trophozoites of A. castellanii near 10 and progressively to 10 densities are capable of expressing a variety of "short-term" survival modes in MPS, notably with the added stress of evaporation. Expression of these alternate survival modes in MPS may relate, in part, to contamination of contact lens cases and difficulties in developing standardized MPS efficacy tests.

The Effects of Contact Lens Materials on a Multipurpose Contact Lens Solution Disinfection Activity Against Staphylococcus aureus

To determine the effect of 8 different lens materials on polyhexamethylene biguanide (PHMB) concentration in multipurpose solution (MPS) levels over time and to determine the effect of lenses on lens solution microbial efficacy over time. Silicone hydrogel lenses and conventional hydrogel lenses were soaked in polypropylene lens cases filled with contact lens MPS containing 1 ppm PHMB for 6, 12, 24, 72, and 168 hours. Cases filled with the same solution without lenses were controls. After each time period, solutions from cases with the 8 types of lenses and controls were assayed for activity against Staphylococcus aureus according to International Organization for Standardization-14729 with modifications. Solutions were analyzed for PHMB concentration at each time point. Some of the different lens materials significantly affected the PHMB concentration (P<0.0001) and the biocidal efficacy. Etafilcon A lenses significantly decreased PHMB levels after only 6 hours of lens soak time. The product lot of MPS used was also significant (P<0.0001). Enfilcon A, senofilcon A, and lotrafilcon B lenses did not significantly decrease PHMB levels. The efficacy of MPS was affected by some lens materials and PHMB concentration. Lens materials differ in their effect on PHMB concentration and the subsequent efficacy of the MPS. Over time, some lens materials can significantly reduce the PHMB concentration and the MPS's microbial activity against S. aureus.

In vitro biocompatibility assessment of multipurpose contact lens solutions: Effects on human corneal epithelial viability and barrier function

To explore the in vitro effects of multipurpose contact lens solutions (MPSs) on corneal epithelial barrier function and viability. Human corneal epithelial cells (HCEpiC) were exposed to 50% MPSs A-G. Viability was determined using metabolic activity, protease release and caspase assays. Barrier function was evaluated using immunostaining for the tight junction protein zonnula occludens-1 (ZO-1) and resistance measurements. MPS A and G did not affect HCEpiC monolayer viability after 2 h, while MPSs B-F significantly decreased viability. There was a significant decrease in stratified HCEpiC viability after exposure to MPSs B-E for 2 h, while there was no effect of MPS A. After exposure of HCEpiC monolayers to MPS A, F or G for 30 min, ZO-1 staining appeared similar to control. HCEpiC exposed to MPSs B and C demonstrated tight junction breakdown. There was no significant change in HCEpiC monolayer resistance after exposure to MPS A or F for 2 h, while MPSs B-E and G reduced resistance. After exposure to MPS A-E, stratified HCEpiC resistance was significantly decreased after 2 or 4 h. The decrease in resistance was significantly less with MPS A as compared to the other MPSs. MPSs caused varying modifications to cell viability and barrier function in monolayer and stratified HCEpiC. MPS A did not alter monolayer HCEpiC viability or barrier function, while MPSs B-G caused significant decreases of at least one parameter. Furthermore, MPS A had significantly less effect than MPSs B-E on viability and barrier function of stratified HCEpiC.

Preservation of Human Tear Protein Structure and Function by a Novel Contact Lens Multipurpose Solution Containing Protein-Stabilizing Agents

Tear film proteins have antimicrobial and other functions that may be lost after denaturation during contact lens wear. A new multipurpose solution has recently become available (Biotrue, Bausch + Lomb Inc., Rochester, NY), which contains protein-stabilizing agents including hyaluronic acid, poloxamine, and sulfobetaine 10, the latter used previously as a laboratory tool to renature proteins. We examine whether this new multipurpose solution formulation can prevent the denaturation of human lactoferrin and lysozyme at physiologic levels in response to a powerful denaturing challenge. Human lactoferrin and lysozyme were treated with sodium dodecyl sulfate (SDS) either with or without an investigational version of the new multipurpose solution (without its two disinfectant agents) (investigational multipurpose solution [iMPS]). The structure was assessed by native-polyacrylamide gel electrophoresis (PAGE), differential scanning calorimetry (DSC), and fluorometry; additionally, antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus was measured. The iMPS prevented an SDS-induced shift in the native-PAGE banding position of lactoferrin. The SDS treatment substantially altered the lactoferrin DSC and fluorescence spectra, indicating that the protein had denatured. This change did not occur in the presence of iMPS. Lactoferrin and lysozyme showed antibacterial and bacteriolytic activity, which was abolished after SDS treatment; this loss of activity did not occur for proteins treated with iMPS. These data clearly show that the iMPS prevents the denaturation of physiologic levels of human lactoferrin and lysozyme by the strongly denaturing surfactant SDS and that stabilized proteins retain their function. We conclude that this solution has the capacity to stabilize the structure and function of tear proteins.

48 Comparative biocompatibility of contact lens multi-purpose disinfecting solutions with soft contact lenses – potential correlations with lens preservative uptake and release profiles

Purpose: Corneal staining associated with contact lens wear and multipurpose solutions (MPS) may indicate ocular surface toxicity. However, corneal staining varies with the time of evaluation. These studies examined corneal staining over time of three MPSs with balafilcon A lenses. Method: Three MPSs were evaluated in two studies: Solution A (COMPLETE® RevitaLens Multi-PurposeDisinfecting Solution [MPDS], Abbott Medical Optics Inc.); Solution B (Opti-Free® RepleniSH® MPDS, Alcon, Inc.] and Solution C (BiotrueTM MPS, Bausch & Lomb Incorporated). These studies were double-masked, contralateral eye, with 29 to 30 subjects. Subjects were randomized to wear lenses soaked in different MPSs in each eye. After baseline evaluations, follow-up visits occurred after one, two, four and six+ hours (end-of-day) of lens wear. Corneal staining was graded on severity and extent by a five-point scale, while comfort was assessed by a 10-point scale. Results: Significant differences in corneal staining extent were found between Solutions A and B at two hours (p=0.037) and Solutions A and C at every follow-up time point (p<0.002). Significant differences in corneal staining severity were found between Solutions A and C at two and four hours (p<0.001). Corneal staining incidence and area were highest with Solution C. No significant difference in comfort was found between any of the solutions at any time point. Conclusions: The clinical performance of different MPSs can be distinctly different between different solution chemistries. Comparative conclusions on corneal staining should factor in the time of evaluation and nature of the kinetics curve.

50 Use of a bovine lens primary organ cultúrete evaluate the toxicity of contact lens caresolution products

Purpose: Corneal staining associated with contact lens wear and multipurpose solutions (MPS) may indicate ocular surface toxicity. However, corneal staining varies with the time of evaluation. These studies examined corneal staining over time of three MPSs with balafilcon A lenses. Method: Three MPSs were evaluated in two studies: Solution A (COMPLETE® RevitaLens Multi-PurposeDisinfecting Solution [MPDS], Abbott Medical Optics Inc.); Solution B (Opti-Free® RepleniSH® MPDS, Alcon, Inc.] and Solution C (BiotrueTM MPS, Bausch & Lomb Incorporated). These studies were double-masked, contralateral eye, with 29 to 30 subjects. Subjects were randomized to wear lenses soaked in different MPSs in each eye. After baseline evaluations, follow-up visits occurred after one, two, four and six+ hours (end-of-day) of lens wear. Corneal staining was graded on severity and extent by a five-point scale, while comfort was assessed by a 10-point scale. Results: Significant differences in corneal staining extent were found between Solutions A and B at two hours (p=0.037) and Solutions A and C at every follow-up time point (p<0.002). Significant differences in corneal staining severity were found between Solutions A and C at two and four hours (p<0.001). Corneal staining incidence and area were highest with Solution C. No significant difference in comfort was found between any of the solutions at any time point. Conclusions: The clinical performance of different MPSs can be distinctly different between different solution chemistries. Comparative conclusions on corneal staining should factor in the time of evaluation and nature of the kinetics curve.

A Novel Mechanism of Increased Infections in Contact Lens Wearers

It is well documented that contact lens wearers have much higher incidences of corneal infections compared with those of non-contact lens wearers, although the exact cause(s) of this increased susceptibility has not been identified. A distinct subset of mucins (MUCs) is present on the ocular surface, acting to protect the integrity of the corneal epithelium. This study was performed to determine whether multipurpose contact lens solutions (MPCLSs) can cause increased infections in the cornea by destroying the protective cell-bound mucin layer. An immortalized human corneal limbal epithelial cell line was treated in the presence of four commonly used MPCLSs or PBS and the expression and release of MUC-16 was assessed. Cells were also cultured with Pseudomonas aeruginosa after MPCLS treatment and internalization of bacteria was assessed by quantitative genomic PCR. Loss of MUC-16 was then correlated with infection rates. Each of the four commonly used MPCLSs examined in this study differentially affected mucin release. The relative effect was correlated with an increase in infection of corneal epithelial cells by P. aeruginosa. The results of this study are consistent with the hypothesis that MPCLSs cause increased infections in the cornea by destroying the protective cell-bound mucin layer.

Importance of Rub and Rinse in Use of Multipurpose Contact Lens Solution

The introduction of contact lens multipurpose disinfection solution (MPDS) that can be used in conjunction with a "no-rub" regimen has simplified lens care requirements. Once adhered to a surface, microorganisms can become less susceptible to disinfection. The aim of the study was to evaluate the effect of various regimen steps on the efficacy of MPDS when used with silicone hydrogel and conventional lenses. Commercially available MPDSs containing polyquad or polyhexamethylene biguanide were used in conjunction with two types of silicone hydrogel (lotrafilcon B and galyfilcon A) and one type of conventional soft contact lenses (etafilcon A). Challenge microorganisms included Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 9027, Serratia marcescens ATCC 13880, Fusarium solani ATCC 36031, Candida albicans ATCC 10231, or Acanthamoeba polyphaga Ros. The effect of regimen steps "rub and rinse," "rinse-only," or "no rub and no rinse" on the disinfection efficacy of test MPDSs was examined using the ISO 14729 Regimen Test procedure. Overall, the greatest efficacy of MPDSs was observed when "rub and rinse" was performed before disinfection with each of the microorganisms tested, regardless of lens type. "No rub and no rinse" steps resulted in a greater load of microorganisms remaining on lenses compared with the other regimens (p < 0.05). When "rinse-only" was performed before disinfection, the MPDS containing polyquad performed generally better (p < 0.05) than MPDSs containing polyhexamethylene biguanide against bacteria. Significantly, less microorganisms were recovered from galyfilcon A than from other lenses (p < 0.05) when MPDSs were used with "rinse-only" step. This study has demonstrated that "rub and rinse" is the most effective regimen and should be recommended in conjunction with all multipurpose lens care solutions and all contact lens types, particularly with silicone hydrogel lenses.

Impact of Multipurpose Solutions Released from Contact Lenses on Corneal Cells

To assess, in vitro, the effect of the release of contact lens multipurpose solutions (MPS) from two silicone hydrogel lenses on human corneal epithelial cells. A monolayer of immortalized human corneal epithelial cells was seeded in a 24-well plate in keratinocyte serum-free medium. Lotrafilcon A (LA) and balafilcon A (BA) lenses were placed on top of the adherent cells for 8 and 24 h, after being soaked in MPS, borate-buffered (Unisol) or phosphate-buffered saline overnight. Cells were assayed for viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay or for α3, β1, and β4 integrin expression and caspase activation by flow cytometry. After 8 h, LA lenses soaked in Unisol, Opti-Free Express (OFX), and ReNu MultiPlus (ReNu) showed decrease in cell viability. LA and BA soaked in Complete Moisture Plus (Complete) had similar viability at around 85% of control. After 24 h, a further decrease in viability was observed with all MPS-soaked lenses; LA soaked in OFX significantly reduced viability compared with Unisol-soaked lenses. In addition, reduced levels of integrin expression for lenses soaked in OFX and ReNu, and for BA soaked in Complete were observed. At 24 h, only LA soaked in OFX led to an increase in caspase activation. Our results indicate an increase in cytotoxicity with borate-based MPS solutions in vitro when compared with both phosphate-buffered saline and borate-exposed lenses, suggesting that biocides and/or additives play a role in the observed cell reaction. Moreover, the mechanism of in vitro solution-induced toxicity appeared to be mediated by lens type, suggesting differences in the preferential adsorption/release profile of certain compounds.

In Vitro Interactions ofFusariumandAcanthamoebawith Drying Residues of Multipurpose Contact Lens Solutions

To examine in vitro effects of evaporation and drying of multipurpose contact lens solutions on survival of Fusarium and Acanthamoeba. Conidia of representative Fusarium from the 2004-2006 keratitis outbreak and trophozoites of Acanthamoeba castellanii were inoculated into commercially available multipurpose contact lens care solutions. These solutions were inoculated with 10(2)-10(6) microbial propagules/mL and were evaporated for at least 24 hours. After drying, nutrient media for recovery of surviving organisms were added to the residues formed in the lids of 38 mm polystyrene Petri dishes. General morphologic patterns of the solution residuals and the distribution and morphologies of the microorganisms were recorded with microscopic imaging. Various multipurpose contact lens disinfection solutions formed distinctive dried residual patterns. Both Fusarium and Acanthamoeba at concentrations tested above 10(3) per mL of disinfection solution were recovered from dried films with replicate testing. Mature cysts of Acanthamoeba not evident in the inocula were observed in sparse numbers in all dried solutions except one (Complete Moisture Plus; Advanced Medical Optics) and control salines where precysts and mature cysts were common. Both fusaria and amoeba tended to be observed in discrete regions of the dried residues. Regions of drying films of multipurpose contact lens disinfection solutions on contact lens cases may induce and harbor dormant-resistant stages of Fusarium and Acanthamoeba. It is hypothesized that the evaporation and drying of multipurpose contact lens disinfection solutions may have been an added risk factor for case contamination among Fusarium and Acanthamoeba keratitis patients. The need for frequent replacement of contact lens cases is enforced.

Nonclinical safety evaluation of boric acid and a novel borate-buffered contact lens multi-purpose solution, Biotrue™ multi-purpose solution

Multipurpose solutions (MPS) often contain low concentrations of boric acid as a buffering agent. Limited published literature has suggested that boric acid and borate-buffered MPS may alter the corneal epithelium; an effect attributed to cytotoxicity induced by boric acid. However, this claim has not been substantiated. We investigated the effect of treating cells with relevant concentrations of boric acid using two cytotoxicity assays, and also assessed the impact of boric acid on corneal epithelial barrier function by measuring TEER and immunostaining for tight junction protein ZO-1 in human corneal epithelial cells. Boric acid was also assessed in an in vivo ocular model when administered for 28 days. Additionally, we evaluated Biotrue multi-purpose solution, a novel borate-buffered MPS, alone and with contact lenses for ocular compatibility in vitro and in vivo. Boric acid passed both cytotoxicity assays and did not alter ZO-1 distribution or corneal TEER. Furthermore, boric acid was well-tolerated on-eye following repeated administration in a rabbit model. Finally, Biotrue multi-purpose solution demonstrated good ocular biocompatibility both in vitro and in vivo. This MPS was not cytotoxic and was compatible with the eye when administered alone and when evaluated with contact lenses. We demonstrate that boric acid and a borate-buffered MPS is compatible with the ocular environment. Our findings provide evidence that ocular effects reported for some borate-buffered MPS may be incorrectly attributed to boric acid and are more likely a function of the unique combination of ingredients in the MPS formulation tested.

Effect of a novel multipurpose contact lens solution on human corneal epithelial barrier function

Purpose To explore the effect of a novel multipurpose contact lens solution (MPS) on the junction protein distribution and barrier function of cultured human corneal epithelial cell monolayers. Methods Cultured human corneal epithelial cells (HCEpiC) were exposed to a novel MPS (MPS A; Biotrue™, Bausch & Lomb) at 50%, 75% and 100% for 10 or 30 min. Four commercially available MPS products, MPS B (AQuify, Ciba Vision), MPS C (COMPLETE MPS Easy Rub, AMO), MPS D (OPTI-FREE Express, Alcon) and MPS E (OPTI-FREE RepleniSH, Alcon) were tested in parallel. Tight junction structure and integrity were evaluated by confocal microscopy using ZO-1 antibody and scanning microscopy (SEM). Quantitative evaluation of MPSs on epithelial barrier function was determined by measuring transepithelial electrical resistance (TEER) across HCEpiC grown on Transwell Clear permeable supports and on electric cell-substrate impedance sensing (ECIS) electrode arrays. Results Overall after exposure to the three concentrations (50%, 75%, and 100%) of MPS A, ZO-1 distribution and fluorescent intensity on the cell surface appeared similar to the media control with continuous tight junctions and clear intercellular junctions. At all measured time points after exposure to MPS A (50% or 75%) there was also no effect on the TEER using both resistance methodologies, and SEM showed that MPS A appeared similar to the Hank's balanced salt solution (HBSS) control. In cells exposed to MPS D there was a dose-dependent change in the distribution of ZO-1, some cell detachment, and a decrease in monolayer resistance at all time points measured. Ultrastructurally, MPS D caused gross changes, including damage to cell junctions and plasma membranes. To a lesser extent, the remaining three commercial MPS products demonstrated some effects on tight junction ZO-1 distribution and/or TEER. Conclusions Based on the in vitro measurements of tight junction protein expression, monolayer integrity, and transepithelial electrical resistance, the novel multipurpose contact lens solution (MPS A) did not alter corneal barrier function as compared to media, PBS or HBSS control. Clinical significance of the observed differences in epithelial barrier function among the MPSs tested needs further investigation.

Contact Lens Solution–associatedAcanthamoebaandFusariumKeratitis

To the Editor: Verani et al. (1) detailed the 2004–2007 outbreak of Acanthamoeba keratitis (AK) in persons wearing soft contact lenses who used Complete MoisturePlus (CMP) multipurpose contact lens solution (Advanced Medical Optics, Santa Ana, CA, USA). They noted similarities between the AK outbreak and the Fusarium keratitis (FK) outbreak of 2004–2006, including the concomitant time frame and association with a particular solution, ReNu with MoistureLoc (Bausch & Lomb, Rochester, NY, USA). Both solutions were new products introduced within 1 year before the respective outbreaks. In neither outbreak was the solution contaminated; in both outbreaks, implicated bottles were from multiple lots, suggesting that each outbreak resulted from insufficient antimicrobial activity. However, in the FK outbreak, all reported cases involved bottles produced at 1 (Greenville, SC, USA) of 4 multinational Bausch & Lomb manufacturing plants (2). After a Food and Drug Administration inspection of the Greenville facility, Bausch & Lomb was cited for inadequacies in temperature control during production, storage, and transport of its products in and beyond the plant (3). We experimentally demonstrated that, when exposed to prolonged temperature elevation, ReNu with MoistureLoc loses more in vitro fungistatic activity than do other contact lens solutions. We concluded that improper temperature control of ReNu with MoistureLoc may have contributed to the FK outbreak (4). We are aware of no other theory that adequately explains why only ReNu with MoistureLoc from only 1 plant was implicated. CMP was manufactured and used internationally; AK has a much higher incidence in Europe and Hong Kong than in the United States (5), and CMP–associated AK has been reported internationally (6). Therefore, it would seem critical to know, and we would like the authors to comment on, whether the geographic pattern of the AK coincided with distribution of CMP solution from >1 Advanced Medical Optics manufacturing plants and, if so, the relevance of that information.

Removal of Biofilm from Contact Lens Storage Cases

Lens case hygiene practices are important in maintaining safe contact lens wear. However, the effectiveness of various lens case cleaning practices have not been evaluated and compared. This in vitro study aimed to evaluate and compare the efficacy of cleaning practices that are most commonly carried out by lens wearers and recommended by practitioners. Pseudomonas aeruginosa 122, Serratia marcescens ATCC 13880, and Staphylococcus aureus ATCC 6538 were the challenge bacteria for biofilm formation on unused lens cases from two different manufacturers. After establishment of the biofilm, each lens case was subjected to one of the six cleaning regimens: "rinsed," "rubbed and rinsed," "air-dried," "soaked in a multipurpose contact lens solution," "tissue-wiped," and "lids recapped." The level of residual biofilm was quantified at the end of each cleaning regimen. The efficacy of each cleaning regimen was then compared. Mechanical rubbing and wiping of lens cases were the most effective cleaning regimen tested in reducing biofilm. Soaking lenses in disinfecting solution for 6 hours removed the majority of biofilm from lens cases. Rinsing lens cases alone provided only minimal efficacy in reducing biofilm. Air-drying or recapping the cases with the lid without any other additional cleaning methods were the least efficient at removing biofilm. Based on this study, digital rubbing and rinsing and/or wiping the lens cases with tissue is recommended. Air-drying or recapping the lens case lids after use without any additional cleaning methods should be discouraged with non-antimicrobial lens cases.

Development of a new contact lens multipurpose solution: Comparative analysis of microbiological, biological and clinical performance

Purpose Antimicrobial, cytotoxicity and clinical performance of a new soft contact lens multi-purpose solution (COMPLETE ® RevitaLens) based on polyquaternium-1 and alexidine dihydrochloride (NuMPS) was evaluated. Methods Antimicrobial efficacy was assessed according to ISO 14729 for both biocidal and regimen performance against bacteria and fungi. Acanthamoeba efficacy was tested along with ability to retain antimicrobial activity on partial evaporation. In vitro cytotoxicity of NuMPS and OPTI-FREE ® RepleniSH ® MPS (MPS-3) was assessed based on ISO 10993-5 and United States Pharmacopeia (USP) methods. In addition, a 3 month, double-masked, parallel group clinical trial comparing safety and acceptability with respect to MPS-3 was conducted with 4 silicone hydrogel (SiHy) and FDA Group IV lens types. Results NuMPS showed broad antimicrobial efficacy, including Acanthamoeba, giving a 3–4 log 10 reduction in viability after 6 hours contact time. NuMPS also passed ISO 14729 regimens with SiHy and etafilcon lenses for bacteria, fungi and also Acanthamoeba. The cytotoxicity of NuMPS was equivalent or better compared to MPS-3. In the clinical trial, there was no statistically significant between-group difference in corneal staining (p > 0.05). Patients using MPS-3 had more adverse events than patients using NuMPS: 11.8 % (11/93) versus 2.8 % (5/177), respectively, (p < 0.05). There were no differences noted in cleanliness or wearing comfort (p > 0.05). Conclusion Taken together, the results of these studies indicate that the NuMPS is a novel and effective soft contact lens care solution.

Impact of assay selection and study design on the outcome of cytotoxicity testing of medical devices: The case of multi-purpose vision care solutions

Medical device biocompatibility testing usually includes a cytotoxicity component. Assay selection and protocol design often depend on a specific testing standard rather than on the characteristics of the medical device. To better understand the impact of assay selection on study outcome of unstructured medical devices, we evaluated contact lens multi-purpose solutions (MPS) in the agar diffusion, direct contact and two elution cytotoxicity assays. To simulate the conditions of use, MPS were evaluated alone and in combination with contact lenses. All MPS passed the agar diffusion assay (n=3) and extracts prepared from contact lenses soaked in MPS passed the USP elution assay (n=3). Both the duration of contact and MPS concentration impacted the outcome of a modified elution assay. When tested at 25% strength for 48h, all MPS evaluated were non-cytotoxic (n>3). Test article movement and mechanical damage were significant issues with the direct contact assay. Movement was effectively controlled by manipulating contact lens orientation while using 0.8mL culture medium. All MPS passed the USP direct contact cytotoxicity test when evaluated using this optimized methodology (n=3). These data are consistent with MPS results in ocular irritation studies in rabbits (n=3).

The Disinfection Efficacy of MeniCare Soft Multipurpose Solution Against Acanthamoeba and Viruses Using Stand-Alone Biocidal and Regimen Testing

To assess the disinfection efficacy of MeniCare Soft contact lens multipurpose solution against Acanthamoeba and viruses in suspension and when inoculated on to contact lenses and subjected to rub-and-rinse or no-rub-and-rinse care regimes. MeniCare Soft was challenged with Acanthamoeba spp trophozoites or cysts, herpes simplex virus (type 1), adenovirus (type 8), and poliovirus (type 2) and the log reduction in Acanthamoeba viability and viral infectivity determined over time. In addition, contact lenses were incubated with Acanthamoeba and viruses and the number of viable organisms determined after the lenses were processed using rub-and-rinse or no-rub-and-rinse care regimes followed by a 4 hr soaking time. MeniCare Soft showed >3 log reduction against Acanthamoeba spp trophozoites and cysts after 6 hr exposure. Approximately 1 log reduction was found against the 3 viruses after 4 hr exposure. No surviving Acanthamoeba trophozoites or cysts were recovered from any of the contact lens tested when MeniCare Soft was used in a rub-and-rinse or no-rub-and-rinse care regimes (>5.0 log reduction). Rub-and-rinse regimen resulted in a 4.5 to 5.0 log reduction in viruses compared with 3.7 to 5.2 log when no-rub-and-rinse was used. MeniCare Soft showed effective disinfection efficacy against Acanthamoeba trophozoites and cysts using solution and regimen assays. The viruses were more resistant to disinfection in solution but were removed effectively from contact lenses using a rub-and-rinse or no-rub-and-rinse care regimen.

Concurrent Acanthamoeba and Fusarium Keratitis With Silicone Hydrogel Contact Lens Use

To report a case of simultaneous Acanthamoeba and Fusarium keratitis associated with no-rub multipurpose contact lens solution and silicone hydrogel contact lens use. Observational case report. A 39-year-old woman was referred for worsening of a presumed bacterial corneal ulcer in the setting of silicone hydrogellens wear with occasional overnight wear, no-rub multipurpose contact lens solution use, and combined topical antibiotic/corticosteroid treatment. Initial corneal scrapings and culture confirmed Acanthamoeba and Fusarium solani, corroborated by in vivo confocal microscopy findings, yet despite topical chlorhexidine 0.02%, propamidine 1%,neomycin/polymyxin B ointment, and natamycin 5% along with oral itraconazole, the ulcer worsened. Four days after amoebic and fungal therapy initiation, it was discovered that the pharmacy accidentally dispensed neomycin/polymyxin B/dexamethasone, and despite immediate discontinuation, therapeutic penetrating keratoplasty from corneal melting was ultimately required. Corneal histopathology confirmed the presence of amoebic cysts and fungal elements. Coexisting infection with Acanthamoeba and Fusarium species can occur in contact lens wear. Atypical infection must be considered in patients with corneal ulcers demonstrating poor therapeutic response in the setting of contact lens wear. Corticosteroids should be used with extreme caution in contact lens–related corneal infections, especially when the diagnosis remains unknown because they can lead to acceleration of active infection and keratolysis.

Disinfection Efficacy and Encystment Rate of Soft Contact Lens Multipurpose Solutions Against Acanthamoeba

To assess the ability of commercial and experimental soft contact lens multipurpose solutions (MPS) to promote Acanthamoeba trophozoite encystment and their biocidal efficacy against Acanthamoeba trophozoites and cysts. The effects on encystment and disinfection efficacy by the incorporation of propylene glycol (PG) in the formulation of MPS were also investigated. Acanthamoeba trophozoites (Acanthamoeba castellanii ATCC 50730 and Acanthamoeba polyphaga CCAP 1501/3G) were inoculated into MeniCare Soft, MeniCare Soft (-PG), Epica Cold II, OptiFree Plus, and Rohto C cube Softone-Moist MPS, and the percentage of encystment induced by each solution was determined after 24 hr. In addition, Acanthamoeba trophozoites and cysts (A. castellanii ATCC 50730 and A. polyphaga CCAP 1501/3G and Ros) were also inoculated into each of the five MPS, and their log reduction determined after 0, 1, 4, 6, and 24 hr of incubation using stand-alone assays. Significantly higher encystment rates were found with Epica Cold II for A. polyphaga CCAP 1501/3G and Rohto C cube Softone-Moist for A. polyphaga and A. castellanii compared with the other MPS assessed (P<0.05). MeniCare Soft, MeniCare Soft (-PG), and Opti-Free Plus produced little or no encystment, with mean encystment values ranging from 0.0% to 2.0%. A significantly higher disinfection efficacy was found with MeniCare Soft, MeniCare Soft (-PG), and Epica Cold II compared with Opti-Free Plus and Rohto C cube Softone-Moist (P<0.05). Significant differences in encystment rate and disinfection efficacy between MPS were found. The presence of PG in the formulation of MeniCare Soft did not affect the disinfection efficacy or the encystment rate. The latter indicates that other factors play a role in the induction of Acanthamoeba encystment after inoculation into MPS.