Multipurpose Contact Lens Solutions Research Articles

Evaluating the cytotoxicity of contact lens multi-purpose solutions in an in vitro lens system

Purpose: To investigate the relative cytotoxic effects of contact lens multipurpose solutions on cultured crystalline lenses.Methods: A comparison of the fluorescence emission levels of cultured bovine lenses as affected by three hour experimental exposure to three contact lens multipurpose solutions (COMPLETE Moisture Plus, AMO; OPTI-FREE Express, Alcon; and ReNu MultiPlus, Bausch & Lomb) was carried out. The pre- and post-exposure fluorescence levels of the lenses were obtained and values were compared to baseline and control measurements.Results: The solutions yielded varying degrees of cytotoxicity, demonstrating significant (p < 0.01) reversible reduction of cellular viability levels of the cultured crystalline lenses as revealed by the degree of fluorescence emissions in the following order (OPTI-FREE Express > ReNu MultiPlus > COMPLETE MoisturePlus multi-purpose solutions)Conclusions: The results show that OPTI-FREE Express and ReNu MultiPlus solutions exhibited more cytotoxic effect compared to COMPLETE MoisturePlus solution. The findings support reportsfrom previous clinical and laboratory studies. These results suggest that the in vitro approach herein presented would be a valuable system for relatively inexpensive and repeatable laboratory investigations of the possible ocular surface reactions of ophthal-mic solutions, cosmetics and pharmaceuticals at pre- and during commercial phases.

Cytotoxicity Testing of Multipurpose Contact Lens Solutions Using Monolayer and Stratified Cultures of Human Corneal Epithelial Cells

To investigate in vitro cytotoxicity of five marketed multipurpose contact lens solutions (MPS) on the morphology, viability, and barrier function of monolayer and stratified human corneal-limbal epithelial cells. Cells were exposed to MPS for 10, 20, or 60 minutes. In monolayer cultures, effects of the MPS on cell morphology were observed using Hoffman modulation contrast microscopy. Cell proliferation after exposure to MPS was evaluated and cytotoxicity of the MPS was determined using a live/dead cell assay and flow cytometry. In stratified cultures, multilayer corneal epithelial constructs were established on membrane inserts. Effects of the MPS on the morphology and barrier function of stratified cultures were determined using microscopy, a fluorescein permeability test, and measurement of trans-epithelial resistance. In monolayer cultures, none of the MPS damaged cells during a 10-min exposure. All of the MPS had varying time-dependent adverse effects on cell morphology, viability, and proliferation during 20- and 60-min exposures. In stratified cultures, none of the MPS had an adverse effect on the structure or barrier function of stratified cultures. Monolayer cultures are highly sensitive to damage by MPS. In contrast, because stratified human corneal-limbal epithelial cultures are resistant to adverse effects of MPS, it is suggested that models that simulate the stratified structure of the corneal epithelium should be used for in vitro toxicologic testing. Caution should be used when interpreting such studies, because in vitro tests may not be predictive of clinical responses to contact lens products that are known to be safe when used as directed.

Analysis of polyhexamethylene biguanide in multipurpose contact lens solutions

The objective of this study was to establish a reasonably simple and reliable method to measure very low concentrations of polyhexamethylene biguanide (PHMB) in multipurpose contact lens solutions (MPSs). By using a weak cation exchange solid phase extraction cartridge to extract the PHMB from MPS, followed by HPLC analysis using an evaporative light scattering detector, low levels (0.1 ppm) of PHMB were detected. Application of this method to a series of off-the-shelf MPS with PHMB as the active ingredient demonstrated these solutions contain 1 ppm. The contact lens solution with hydrogen peroxide as the active ingredient gave no peak where the PHMB peak eluted. The Polyquad ® contact lens solution generated a peak close to the retention time of PHMB. Recovery of PHMB from fortified hydrogen peroxide contact lens solution was good at 0.25 ppm and above; 105% with a RSD of 17% or less. The repeatability of the HPLC system ranged from 4 to 11% RSD; the reproducibility of the entire method was less than 17.5% RSD. Storage and stability studies indicated that storage of MPS with PHMB for chemical analysis are not temperature dependent, but are affected by the composition of the container in which the contact lens solution is stored.

Comparison of the effect of multipurpose contact lens solutions on the viability of cultured corneal epithelial cells

To determine the effect of four marketed multipurpose contact lens solutions (MPSs) on corneal epithelial cell viability. Comparison of the effect of MPS A (Renu MultiPlus, Bausch & Lomb), MPS B (OPTI-FREE Express, Alcon), MPS C (AQuify, CibaVision), and MPS D (OPTI-FREE RepleniSH, Alcon) on cell viability was performed by quantifying cellular ATP content, resazurin reduction, and lactate dehydrogenase (LDH) release in transformed human corneal epithelial cells (HCEpiC) and primary bovine corneal epithelial cells (BCEpiC). Significant reductions in cellular ATP content were observed at 40% solution and above with both MPS B and MPS D, compared to at 100% only for MPS A and MPS C, and similar results were obtained in BCEpiC. Effects on resazurin reduction were also less in HCEpiC exposed to increasing doses of MPS A and MPS C than in cells exposed to MPS B and MPS D. After 15 min, HCEpiC viability measured by both resazurin reduction and cellular ATP levels was significantly lower for cells exposed to MPS B, MPS D, and MPS C, while HCEpiC exposed to MPS A were not affected. MPS B and MPS D reduced cell viability more than MPS A and MPS C over a 2-h time course in both HCEpiC and BCEpiC. Both MPS B and MPS D can cause large decreases in the viability of cultured corneal epithelial cells even with just a 2h exposure at multiple doses. Significant reduction in cell viability is evident at brief 15-30 min exposures. In contrast, MPS A and MPS C have significantly less effect on the cell viability of corneal epithelial cells at multiple doses, after these short exposure times.

Soft Contact Lens Disinfection Solution Efficacy: Clinical Fusarium Isolates vs. ATCC 36031

To compare the disinfecting efficacy of five soft contact lens multipurpose disinfection solutions (MPDS) against Fusarium solani clinical isolates and the ISO standard ATCC 36031 strain. Three commercially available and two recalled MPDS were tested using the ISO/CD 14,729 stand-alone test for contact lens care products against 10 ocular isolates of F. solani and the ATCC 36031 strain. The effect of filtering the fungal suspension before incubating in MPDS was also tested. An average log reduction in colony forming units at the manufacturer's minimum recommended disinfection time was determined and compared with criteria for stand-alone disinfection products for each MPDS against each strain. No difference between filtered and unfiltered fungal suspensions was observed for the ISO standard, whereas in one MPDS the representative clinical isolate showed significantly increased resistance when unfiltered. All but one solution met the stand-alone criteria of 1.0-log reduction of colony forming units against the recommended ISO standard strain ATCC 36031. However, there was wide variation in the ability of MPDS to meet the ISO disinfection criteria when tested against clinical isolates. Among the commercially available MPDS, the two polyquaternium-based solutions showed a higher disinfecting efficacy than the biguanide-based solution. The two recalled solutions showed a lower disinfecting efficacy than the polyquaternium-based solutions. Further, the clinical isolates were significantly more resistant to disinfection than was the recommended ISO strain. The effect of filtering the fungal suspension to remove hyphae seems to be relevant in the clinical isolate tested, but not in the ISO strain. Clinical isolates were significantly more resistant to disinfection than the recommended ISO strain in the presence of both the commercially available and the recalled MPDS. The use of clinical isolates in stand-alone disinfection testing is indicated. Because there were significant differences in increased resistance exhibited by clinical isolates and in a mixed (unfiltered) culture the use of a single laboratory strain may be insufficient to provide assurance that the disinfection solution will be effective against clinical isolates.

Resistance of Acanthamoeba Cysts to Disinfection in Multiple Contact Lens Solutions

Acanthamoebae are free-living amoebae found in the environment, including soil, freshwater, brackish water, seawater, hot tubs, and Jacuzzis. Acanthamoeba species can cause keratitis, a painful vision-threatening infection of the cornea, and fatal granulomatous encephalitis in humans. More than 20 species of Acanthamoeba belonging to morphological groups I, II, and III distributed in 15 genotypes have been described. Among these, Acanthamoeba castellanii, A. polyphaga, and A. hatchetti are frequently identified as causing Acanthamoeba keratitis (AK). Improper contact lens care and contact with nonsterile water while wearing contact lenses are known risk factors for AK. During a recent multistate outbreak, AK was found to be associated with the use of Advanced Medical Optics Complete MoisturePlus multipurpose contact lens solution, which was hypothesized to have had insufficient anti-Acanthamoeba activity. As part of the investigation of that outbreak, we compared the efficacies of 11 different contact lens solutions against cysts of A. castellanii, A. polyphaga, and A. hatchetti (the isolates of all species were genotype T4), which were isolated in 2007 from specimens obtained during the outbreak investigation. The data, generated with A. castellanii, A. polyphaga, and A. hatchetti cysts, suggest that the two contact lens solutions containing hydrogen peroxide were the only solutions that showed any disinfection ability, with 0% and 66% growth, respectively, being detected with A. castellanii and 0% and 33% growth, respectively, being detected with A. polyphaga. There was no statistically significant difference in disinfection efficacy between the 11 solutions for A. hatchetti.

Clinical Evaluation of Long-Term Users of Two Contact Lens Care Preservative Systems

To clinically evaluate long-term users of two different contact lens care preservative systems and to investigate whether prolonged use is associated with an increase in the prevalence of dry eye. Eighty-nine wearers of group IV hydrogel or silicone hydrogel lenses participated in this one-visit, investigator-masked study. Subjects were required to have consistently used a polyhexamethylene biguanide (PHMB) or polyquaternium-1 (PQT) based solution for 2 years. Consistent use was defined as 80% for the past 2 years and 100% for the past year. Clinical assessments included: average and comfortable wear time; overall and end-of-day comfort; signs of dryness, discomfort, burning or stinging, grittiness or scratchiness and visual changes; non-invasive and fluorescein break-up-time; pre-ocular tear film lipids, tear meniscus height, Schirmer and fluorescein clearance tests; limbal and bulbar hyperemia; palpebral roughness; corneal and conjunctival staining; lens front surface wetting; and lens film deposits. Significantly more grittiness or scratchiness was reported by subjects using a PHMB-containing system (67% vs. 44%; P = 0.02). Palpebral roughness and hyperemia were significantly greater in the PHMB group wearing group IV lenses (P = 0.01 and P = 0.05, respectively). Corneal staining was significantly higher in the PHMB users in all four peripheral sectors (P < 0.01). Nasal and temporal conjunctival staining was also significantly higher for users of PHMB-containing systems (P < 0.05). Front surface lens wettability was significantly better for group IV PQT users compared to PHMB users (P = 0.008), with 84% vs. 72%, respectively, with lenses graded by the investigator as having "good" or "excellent" wettability. Significantly higher levels of lens front surface film deposits were noted with PHMB users (P = 0.007), with 58% of group IV lenses treated with PHMB compared with 38% of group IV lenses treated with PQT showing some lens front surface film deposition. No significant differences between the two preservative system groups were noted for the range of dry eye evaluations nor the remaining clinical assessments. Differences in both ocular and lens characteristic were observed between long-term users of two preservative systems used in many contact lens multi-purpose solutions. The findings from this study did not support the hypothesis that prolonged use of PHMB-containing solutions leads to dry eye. Additional studies including a larger sample size and perhaps longer use of the systems could help to further elucidate differences in clinical performance between systems.

Effects of Contact Lens Multipurpose Solutions on Human Corneal Epithelial Survival and Barrier Function

To examine the effect of 4 commercially available contact lens multipurpose solutions (MPS) on the viability and barrier function of human corneal epithelial cells in vitro. Immortalized human corneal epithelial cells were exposed to 4 solutions, MPS A, B, C, and D with culture medium and Hanks' Balanced Salt Solution as controls. MTT assay was used to evaluate cell viability. ApopTag Fluorescein Apoptosis assay was used to detect cell death in situ. Corneal epithelial barrier function was evaluated by fluorescein permeability and immunofluorescent staining for tight junction proteins zonula occludens (ZO)-1 and occludin. Corneal epithelial survival rates, evaluated by MTT assay showed no statistical difference between MPS A and the culture medium or Hanks' Balanced Salt Solution controls. MPS B, C, and D were associated with significantly less cell survival than the controls after exposure for 6 hrs (all P<0.01). Compared with the controls, the MPS A did not increase cell apoptosis, whereas the other 3 caused higher apoptotic rates. The epithelial permeability after exposure to MPS A was similar to controls and significantly lower than MPS B and MPS D (P<0.01). The tight junction proteins ZO-1 and occludin were well maintained after exposure to MPS A. In contrast, the expression of ZO-1 and occludin were largely disturbed by the other 3 MPS solutions. The current marketed contact lens MPS may have negative effects on human corneal epithelial viability and barrier function. Among 4 MPS studied, MPS A maintains the cell viability and barrier function significantly better than other 3 marketed products.

Compatibility of two new silicone hydrogel contact lenses with three soft contact lens multipurpose solutions*

The purpose of this study is to assess corneal staining and subjective symptom ratings with six different silicone hydrogel contact lens/multipurpose solution combinations, including the recently launched Menicon PremiO silicone hydrogel contact lens, after the first night of soaking the lenses in solution. This study is a prospective, single-centre, subject-masked, contralateral, crossover, daily wear clinical trial in which subjects were randomly fitted in the morning with a different lens/solution combination in each eye, asked to wear the lenses for the whole day (at least 12 h), soak each of the lenses overnight in one of the test solutions and insert the lenses on the following morning. Subjects were asked to come on that morning for assessment of corneal staining and subjective ratings. All subjects repeated this procedure on another two occasions in order to collect the results of the six different lens/solution combinations: Menicon PremiO/MeniCare Soft; Menicon PremiO/Complete 10; Menicon PremiO/OptiFree Express; Acuvue Oasys/MeniCare Soft; Acuvue Oasys/Complete 10; Acuvue Oasys/OptiFree Express. Menicon PremiO lenses were associated with a lower level of corneal staining overall, and in the nasal and temporal locations, compared with Acuvue Oasys lenses (p < 0.05). No significant differences were found in corneal staining between solutions (p > 0.05). An overall rate of solution-induced corneal staining per eye of 12% was found. Symptoms were very similar among the six different lens/solution combinations (p > 0.05). The lower level of corneal staining found with Menicon PremiO lenses compared with Acuvue Oasys lenses might be attributed to material, surface and design differences between lens types. The overall rate of solution-induced corneal staining and symptomatology found between the different lens/solutions combinations is consistent with previous studies.

Severe ocular infections with contact lens: role of multipurpose solutions

To determine whether multipurpose solutions, widely used for contact lens disinfections, could be at the origin of ocular pathologies (contact lens intolerance and ocular infections). An observational cohort study (questionnaire analysis) was carried out to estimate the number of contact lens wearers, type of infection, and type of lens care regimen used by patients. Besides, multipurpose solutions cytotoxicity (necrosis and apoptosis) was evaluated on a conjunctival cell line using cytofluorometry. In the general population, 59% of contact lens wearers use multipurpose solutions whereas 35% use oxidative products. Of the questioned contact lens wearers with ocular infections, 80% used multipurpose solutions. Multipurpose solutions are therefore not efficient enough against microorganisms, and cannot be considered as disinfectant solutions but only as preservatives. However, preservatives are known to be toxic to ocular surface, so apoptosis induced by multipurpose solutions could lead to ocular surface diseases. Our cytofluorometry study allowed us to demonstrate that contact lens multipurpose solutions containing preservatives are cytotoxic through caspase 3 induction, chromatin condensation and P2X7 cell-death receptor activation, in contrast with unpreserved sterile saline solutions that were found inert. Multipurpose solutions seem to be preservative but not disinfecting solutions. They are not adapted to the final rinse of contact lenses because of apoptosis induction. It could explain part of lens intolerance.

Impact of Contact Lens Group on Antifungal Efficacy of Multipurpose Disinfecting Contact Lens Solutions

To evaluate and compare the in vitro effectiveness of multipurpose contact lens solutions (MPDS) to inhibit fungal colonization of Food and Drug Administration (FDA) contact lens groups. Contact lenses from FDA groups I (low water content, nonionic), II (high water content, nonionic), III (low water content, ionic), and IV (high water content, ionic) were placed in sterile contact lens cases with 2 mL of ReNu MultiPlus, ReNu with MoistureLoc, or OPTI-FREE RepleniSH. Each contact lens-multipurpose solution combination was challenged with 0.1 mL of 10(6) colony-forming units/mL of Fusarium oxysporum and incubated at room temperature. Contact lenses and aliquots from phosphate-buffered saline rinse solutions, multipurpose solutions in cases, and lens cases were sampled at 24, 48, and 72 hours, plated on Sabouraud's agar, incubated at room temperature, and observed for growth (i.e., adhesion) for 1 to 7 days. Used multipurpose contact lens solutions met or exceeded the 1-log reduction requirement of the FDA stand-alone test. Viable fungal colonies were recovered from group II lenses after 24 hours of storage in all three multipurpose solutions. Colonization was also detected with at least one contact lens-multipurpose solution pairing from groups I, III, and IV. Fungi were not recovered from lens-solution combinations after 24 hours or from phosphate-buffered saline solutions or lens cases at any period. Antifungal activity of contaminated multipurpose solutions may be insufficient to prevent fungal colonization of contact lens materials despite meeting or exceeding the FDA stand-alone test criteria. Colonized lens may increase the risk of fungal keratitis.

Fusariumkeratitis and contact lens wear: facts and speculations

Over the past several decades mycotic keratitis has been considered a rare sequel to hydrogel contact lens wear. In 2005--2006 an upswing in the incidence of Fusarium keratitis was associated with a disproportionate use of one multipurpose contact lens solution (MPS, ReNu with MoistureLoc, Bausch & Lomb, Rochester, NY). The MPS, as manufactured and marketed, was sterile and met regulatory guidelines for antimicrobial activity. A multivariant interaction of poor hygienic practices and the contact lens paraphernalia were associated with a mostly selective contamination in or on the lens storage case by members of the F. solani/F. oxysporum species complexes from the environment of the user. A decline of the anti-fusaria properties of the MPS in the lens case appeared related to its dissociation from drying, or dilution and the potential for sorption of antimicrobial solution components (e.g., alexidine) to various hydrogel lenses. These factors and capacities of the fusaria for rapid amplification by microcycle conidiation, production of dormant resistant cells, and potential for attachment and penetration of hydrogel lenses, were linked to the occasional selective fungal survival and growth during storage of the lens in MPS. Lack of a manual rubbing-cleaning step in the MPS disinfection process was considered a risk factor for keratitis.

Differences Among Strains of the Fusarium oxysporum-F. solani Complexes in Their Penetration of Hydrogel Contact Lenses and Subsequent Susceptibility to Multipurpose Contact Lens Disinfection Solutions

To examine in vitro conditions for attachment and penetration of silicone hydrogel (SH) lenses by clinical isolates of the Fusarium oxysporum-F. solani complexes and the relative susceptibilities of the fusaria in the lens matrices to multipurpose contact lens solutions (MPSs). SH soft contact lenses were soaked in Sabouraud dextrose broth (SAB) for 2 hours and transferred to 3.0 mL of phosphate-buffered saline (PBS). The lenses were inoculated with representative isolates of both complexes and incubated on a shaker at ambient temperature. Lenses were examined daily by light microscopy before and after rinsing and rubbing in MPS. Selected lenses penetrated by fungi were rinsed and rubbed with MPS and held in MPS for 6 hours, transferred to PBS with 0.03% SAB, and examined daily. The degree and rate of lens penetration of contact lenses by isolates of the F. oxysporum-F. solani complexes varied with lens type and the strain. Isolates obtained from patients with Fusarium keratitis produced on and within lenses chlamydospores that seemed similar to those observed in lenses actually worn by patients when they developed Fusarium keratitis. Clinical isolates showed greater capacities than those of a standard test strain to penetrate lenses and to survive exposures to various MPSs. In general, isolates of F. solani were more readily removed from lenses by rubbing than were isolates of F. oxysporum. The ability of Fusarium spp. to attach to and penetrate SH lenses in vitro varies with the lens type and strain, and this ability may make infectious keratitis more likely. We recommend the incorporation of a rubbing step in the MPS disinfection of hydrogel lenses to reduce the risk of fungal keratitis.

Cytotoxicity of contact lens multipurpose solutions: Role of oxidative stress, mitochondrial activity and P2X7 cell death receptor activation

Objective To investigate the cytotoxicity of multipurpose solutions used for contact lens disinfection. Methods Four multipurpose solutions (Optifree ® containing quaternary ammonium as preservative, Renu ®, Solocare ® and Complete ® containing polyhexamethylene biguanide as preservative) were incubated on a conjunctival cell line to evaluate their capacity to induce necrosis (neutral red test), intracellular redox status alteration (Alamar Blue test), reactive oxygen species overproduction (DCFH-DA and dihydroethidium tests), mitochondrial alterations (NonylAcridine Orange and JC-1 tests) and to activate P2X7 cell death receptor (YO-PRO-1 test). Tests were performed using cytofluorometry and inverted fluorescence microscopy. Results Our results showed that multipurpose solutions induced necrosis, in addition to oxidative stress. Optifree ® induced oxidative stress with increased mitochondrial mass, Renu ®, Solocare ® and Complete ® induced whether a decrease in reactive oxygen species production with mitochondrial alterations, or an increase in reactive oxygen species production, but each solution stimulated P2X7 cell death receptor activation. Early stimulation of P2X7 cell death receptor, prior to any superoxide production, demonstrated the possible involvement of this receptor in the oxidative stress process. Conclusion These new findings suggest that most of multipurpose solutions are toxic with oxidative stress and apoptosis induction.

Attachment to and Penetration of Conventional and Silicone Hydrogel Contact Lenses by Fusarium solani and Ulocladium sp. In Vitro

To analyze the relative capacities of Fusarium solani and Ulocladium sp. to attach to and penetrate silicone hydrogel soft contact lenses. Representative silicone hydrogel (SH, siloxy complexes) and conventional [hydroxyethylmethylacrylate (HEMA)] soft contact lenses were exposed to suspensions of F. solani and Ulocladium sp. in vitro (10 conidia/mL in phosphate-buffered saline). The lenses were incubated with shaking at ambient temperatures and examined after rinsing in a multipurpose contact lens solution (MPS) by light and scanning electron microscopy. Isolates of both genera firmly attached to and penetrated both lens types, but Ulocladium sp. did so in greater density and more rapidly than F. solani. The extent of firm attachment and time needed for penetration into the lenses varied with strain and substratum, particularly with the isolates of F. solani. Morphologic characteristics (eg, penetration pegs, microcycle conidiation, and chlamydospores) of F. solani in the SH and HEMA lenses were similar to those observed in several lenses from patients with ReNu with MoistureLoc (RML)-associated Fusarium keratitis. To our knowledge, this is the first report that F. solani produces coiled penetration pegs in the matrices of SH hydrophilic soft contact lenses similar in morphology to those found in HEMA lenses. F. solani attaches firmly to SH lenses and rarely penetrates the lens matrix, but viable fungal propagules may remain on the lens after vigorous rinsing with MPS. Failure to use a manual cleaning-disinfection procedure may help to explain the increased incidence of Fusarium keratitis associated with contact lens wear.

Efficacy of Contact Lens Multipurpose Solutions Against Serratia Marcescens

To compare the susceptibilities of clinical isolates of Serratia marcescens and the standard ISO ATCC 13880 strain to five contact lens multipurpose disinfection solutions (MPDSs). Five commercially available MPDSs, containing either a polymeric biguanide or polyquaternium, were tested using ISO/CD 14729 stand-alone test for contact lens care products against four ocular isolates of S. marcescens and the strain ATCC 13880. An average log 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 MPDS against each bacterial strain. All the MPDSs tested met the stand-alone criteria of 3-log reduction of viable bacteria against the ATCC strain of S. marcescens. However, there was more variability in their ability to meet disinfection criteria when tested against the clinical isolates. Two of the clinical isolates were significantly more resistant to disinfection than was the recommended ISO strain (p < or = 0.034). Two of the polyquaternium-1-based disinfection solutions (solutions D and E, p < or = 0.005) were less effective overall than the other MPDSs against S. marcescens. The importance of strain selection for the testing of MPDSs is indicated, and the use of a single laboratory strain may be insufficient to provide assurance that the disinfection solution will be effective against clinical isolates. Furthermore, clinical isolates of S. marcescens may show increased resistance to disinfection with polyquaternium.

The comparative clinical performance of a new polyhexamethylene biguanide‐ vs a polyquad‐based contact lens care regime with two silicone hydrogel contact lenses

To compare the clinical performance of a new polyhexamethylene-biguanide (PHMB)- vs a polyquad-based contact lens care regime with two silicone hydrogel contact lenses. This study was a randomised, controlled and investigator-masked (to the lens regimen) clinical study where the clinical performance of two multipurpose contact lens solutions was compared at a single site. Forty-one existing contact lens wearers were recruited and fitted randomly with either galyfilcon A or lotrafilcon A contact lenses. Subjects wore the same lens type for a period of 2 months but used a different care regime (PHMB- and polyquad-based) in a crossover manner, each for a period of 1 month. The primary outcome measure was the difference in corneal staining. Corneal staining was graded in five different locations: central, superior, inferior, temporal and nasal. Measurements of conjunctival redness, limbal redness, conjunctival staining and papillary conjunctivitis were also carried out throughout the study. Biomicroscopic measures were graded using the Efron grading scales. A variety of symptoms were also measured using a visual analogue scale. There was no statistically significant difference in overall corneal staining between lens types (p = 0.16) or care regimens (p = 0.60). Central corneal staining was significantly greater for the polyquad-based care regimen when compared with the PHMB-based care regimen (p = 0.04). Lotrafilcon A lenses showed greater superior corneal staining (p = 0.0004) and papillary conjunctivitis (p = 0.02), and lower comfort on insertion (p = 0.03) when compared with galyfilcon A lenses regardless of the care regime used. There were no statistically significant differences in the other biomicrosopic signs and symptoms between the lens types and the care regimes. Both care regimes performed in a similar clinical manner and are valid for use with the two silicone hydrogel contact lenses used in this study.

Growth and Survival of Fusarium solani-F. oxysporum Complex on Stressed Multipurpose Contact Lens Care Solution Films on Plastic Surfaces In Situ and In Vitro

To analyze factors implicating the association of ReNu with MoistureLoc (ReNu ML) multipurpose contact lens solution (MPS) with the increased incidence of Fusarium keratitis. Used contact lens cases with and without contact lenses and MPS containers were collected from patients with confirmed or possible Fusarium keratitis. Direct microscopy including transparent adhesive tape preparations and swab cultures were used to determine fungal colonization. Survival and growth of selected isolates of Fusarium spp. in drying MPS on plastic surfaces were determined by microscopy and recoverable colony counts on enriched agar. Discrete regions of fungal colonization, including occasional microcycle conidiation and chlamydospore formation, were observed on the surfaces of contact lens cases and, less often, on solution containers that had been used by patients with Fusarium keratitis associated with the use of ReNu ML. Isolates provisionally grouped with the F. solani-F. oxysporum complex were inhibited by fresh MPS in original solution containers and contact lens cases, but survived in stressed (drying) films of MPS, particularly ReNu ML. These in vitro test results were similar to the direct in situ observations of the materials from patients. Selective, rapid growth and survival of cells of the F. solani-F. oxysporum complex on plastic surfaces, particularly of contact lens cases with stressed ReNu ML films, may explain, in part, the recent Fusarium keratitis outbreak.

A fluorometric study of relative ocular lens cytosensitivity to multipurpose contact lens solutions using the resazurin assay method

This study investigated the relative ocular lens cytosensitivity to three multipurpose contact lens solutions using lens culture and resazurin microplate assay method. Comparison in the cell viability levels of the cultured bovine lenses as influenced by 3 h experimental exposure to three contact lens multipurpose solutions (OPTI-FREE Express, Alcon; ReNu MultiPlus, Bausch & Lomb; and COMPLETE Comfort Plus, Allergan) was performed. The pre- and post-exposure fluorescence emission levels of the lenses were obtained, and findings were compared to baseline and control measurements. The solutions demonstrated varying levels of sensitivity ( P < 0.1), exhibiting non-significant to significant reversible disruption of the lenses’cell viability levels as revealed by the fluorescence intensity levels in the following ranked order (COMPLETE < ReNu < OPTI-FREE solutions). The findings show that OPTI-FREE Express and ReNu MultiPlus solutions exhibited more cytosensitive effect compared to COMPLETE Comfort Plus. These results suggest that the resazurin assay together with lens culture would be a reliable system for in vitro investigation of the effect of contact lens solutions and other ophthalmic formulations on ocular tissues.

The Effect of Multipurpose Solutions on the Ocular Surface

We aimed to determine if multipurpose contact lens solutions could solely contribute to adverse ocular surface effects. Three specific multipurpose solutions were evaluated: Bausch & Lomb ReNu MultiPlus (ReNu with MoistureLoc was not evaluated in this study), Alcon No Rub Opti-Free Express, and Advanced Medical Optics Complete Moisture Plus. The impact that solutions have on the ocular surface, if negative, could be adverse. Nearly all recent studies examine the effects of solutions through the contact lens as a vehicle for delivery. The lens itself cannot be completely ruled out as a causal factor. 21 subjects were randomized to one of the three solution groups. Subjects self-administered a solution to their treatment eye four times daily, with the fellow eye serving as the control. Solutions and the test eye were masked to the subject and examiner. A battery of ocular surface testing was conducted at the baseline examination and at every week interval by masked examiner. Non-parametric data was analyzed by Friedman 1-way ANOVA and parametric data by the 1-way repeated measures ANOVA. A reduction in tear breakup time was found to be statistically significant for the ReNu group (P < 0.05). ReNu has frequently been cited as being more cytotoxic. We propose that when used at a high frequency, ReNu preservatives and additives are adverse. Contact lens dropout and/or clinical signs noted by the examiner may be linked to the use of ReNu.