ReNu MultiPlus Research Articles

The influence of lens material and lens wear on the removal and viability of Staphylococcus epidermidis

Purpose The aim of this study was to evaluate the influence of lens material and lens wear on the removal capability of Staphylococcus epidermidis. Assessment of viability of remaining adhered bacteria was another goal of this work. Four silicone hydrogel materials (galyfilcon A, balafilcon A, lotrafilcon A, lotrafilcon B) and one conventional hydrogel material (etafilcon A) were assayed. Methods Detachment studies on S. epidermidis were carried out in a parallel plate flow chamber. Contact lenses (CLs) were fitted to the bottom of the flow chamber and a bacterial suspension was perfused into the system, promoting bacterial adhesion. Afterwards, detachment was stimulated using a multipurpose solution (MPS, ReNu Multiplus ®) and the percentage of removed bacteria estimated through microscopic observation and enumeration. Remaining adhered bacteria were stained with propidium iodide (PI) and enumerated in order to assess their viability. Additionally, the worn lenses were observed by confocal laser scanning microscopy (CLSM) to visualize bacterial distribution along the lens surfaces. Results Bacterial removal was significant ( p < 0.05) for both unworn and worn galyfilcon A and etafilcon A. Galyfilcon A exhibited a detachment percentage of 59.1 and 63.5 while etafilcon A of 62.6 and 69.3, both for unworn and worn lenses, respectively. As far as bacterial viability is concerned, it was found that worn lenses exhibit a superior amount of non-viable bacteria than unworn CLs. Images obtained by CLSM revealed an irregular bacterial distribution for all lens materials. Conclusions It appears that surface and/or bulk structure of the lens material affects removal of S. epidermidis while CL wear influences their viability.

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.

Use of a Human Corneal Epithelial Cell Line for Screening the Safety of Contact Lens Care Solutions In Vitro

Sodium fluorescein permeability assay, alamarBlue assay, and scanning electron microscopy were performed to study the effects of various contact lens disinfecting multipurpose solutions (MPS) on the integrity of the ocular surface epithelium by using corneal epithelial cells. The sodium fluorescein permeability and alamarBlue activity of monolayer cultures of human corneal epithelial cells were compared after exposure to ReNu MultiPlus, OPTI-FREE Express, AQuify 5 Minute, SOLO-care Plus With Aqualube, and Complete Moisture Plus contact lens care solutions for 15 minutes. Additional cell monolayers were prepared for each treatment and were analyzed with a scanning electron microscope after a 10-minute exposure. The sodium fluorescein permeability assay, alamarBlue assay, and scanning electron microscopy showed that OPTI-FREE Express was significantly more damaging to the human corneal epithelial cell monolayer than ReNu MultiPlus, SOLO-care Plus With Aqualube, Complete Moisture Plus, and AQuify 5 Minute contact lens solutions. Cell monolayers treated with OPTI-FREE Express were more permeable to sodium fluorescein and showed lower metabolic activity than cell monolayers treated with the other multipurpose solutions. This experiment shows that ReNu MultiPlus, SOLO-care Plus With Aqualube, Complete Moisture Plus, and AQuify 5 Minute contact lens solutions have a minimal effect on human corneal epithelial cells in culture, whereas OPTI-FREE Express has a higher negative effect on tight junctions, cell membranes, and overall metabolism of these human corneal epithelial cells.

Biocompatibility of Contact Lens Solutions Using Confocal Laser Scanning Microscopy and the In Vitro Bovine Cornea

This study used high-resolution research confocal laser scanning microscopy to study the epithelium of fresh bovine corneas treated with two contact lens solutions. Fresh bovine corneal buttons were stained with a combination of the cell-permeable mitochondrial- and nuclear-specific dyes rhodamine 123 and Hoechst 33342 or acridine orange and imaged with a confocal laser scanning microscope. High-resolution X,Y images of the corneal epithelium were taken with a Zeiss 510 confocal laser scanning microscope at a 0.44-062 -microm Z step, and three-dimensional images of the entire thickness of the corneal epithelium were reconstructed. Semiautomated quantitative MatLab software analysis was applied to count the mitochondria in each optical slice. The effects of treatment for 30 minutes with OPTI-FREE Express and ReNu MultiPlus No Rub were investigated and compared to Hanks' balanced salt solution controls. This study showed the feasibility of using the confocal laser scanning microscope with fluorescent dyes to study organelles throughout the epithelial layers of fresh unfixed bovine corneas. The mitochondria in the intermediate and basal epithelium are abundant and range in length from less than 1 microm to threads greater than 15 microm, with a tendency to accumulate around the nuclei. Image analysis indicated significantly fewer mitochondria only in the superficial epithelium after treatment with ReNu MultiPlus No Rub treatment. OPTI-FREE Express treatment produced significantly fewer mitochondria not only in the superficial but also in the intermediate epithelial layers. OPTI-FREE Express has the potential for deeper mitochondrial effects compared to ReNu MultiPlus No Rub and Hanks' balanced salt solution controls.

Clinical Evaluation of Silicone Hydrogel Lens Wear With a New Multipurpose Disinfection Care Product

To evaluate subjective symptoms and clinical signs in silicone hydrogel contact lens wearers with three different multipurpose solution (MPS) lens care regimens. In a double-masked, randomized, concurrently controlled study, 233 subjects from 12 clinical sites wore one of two silicone hydrogel lens brands (ACUVUE Advance or Focus NIGHT & DAY) for 1 month on a daily-wear basis supported by a new reconditioning multipurpose disinfecting solution (MPDS) preserved with POLYQUAD and ALDOX, regimen 1 (OPTI-FREE RepleniSH Multi-Purpose Disinfecting Solution), or by one of two MPSs preserved with polyhexamethyl biguanide, regimen 2 (ReNu MultiPlus Multi-Purpose Solution No Rub Formula) or regimen 3 (Complete MoisturePLUS Multi-Purpose Solution). Significant differences in favor of regimen 1 were found in subjective responses of subjects wearing ACUVUE Advance lenses. For Focus NIGHT & DAY lens wearers, regimen 1 was associated with significantly less corneal staining (severity [P=0.0019], area [P=0.0077]) than regimen 2 was. The average number of times per day that rewetting drops were used was significantly higher for subjects randomized to regimen 3 than for subjects using regimen 1. The clinical performance of the new MPDS product with silicone hydrogel lenses was generally as good as or better than the two comparative polyhexamethyl biguanide-preserved MPSs. Clinical differences were evident between the products. Practitioners should be aware that MPS product choice for use with silicone hydrogel lenses may lead to different clinical outcomes, particularly in regard to stress on the ocular surface, as evidenced by the corneal staining response.

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.

Risk Factors for Contact Lens–Related Fusarium Keratitis

To evaluate the specific contact lens-related or other factors that may contribute to the outbreak of Fusarium keratitis. A case-control study was conducted of Fusarium keratitis in contact lens users in Singapore from March 1, 2005, to May 31, 2006, and included 61 patients with Fusarium keratitis and 188 population-based and 179 hospital-based control subjects. Interviewers asked about contact lens solution use and other risk factors. Patients with Fusarium keratitis were more likely to use ReNu contact lens solutions (Bausch & Lomb, Rochester, NY) 58 [95.1%] of 61 cases) than were either population-based (62 [34.3%] of 181) or hospital-based (50 [30.1%] of 166) control subjects. After controlling for age, sex, contact lens hygiene, and other factors, the use of ReNu with MoistureLoc significantly increased the risk of Fusarium keratitis (odds ratio, 99.3; 95% confidence interval, 18.4-535.4; P<.001), and the risk was 5 times higher compared with the risk with use of ReNu MultiPlus, a multipurpose solution (odds ratio, 21.5; 95% confidence interval, 4.0-115.5; P<.001). The use of ReNu contact lens solutions significantly increased the risk of contact lens-related Fusarium keratitis in Singapore. Our data support the recall of ReNu MultiPlus from the Singapore market and the need for further investigations into the role of ReNu MultiPlus in the development of Fusarium keratitis in other populations.

Fungal Keratitis Associated With Contact Lenses

JAMA Multistate Outbreak of<i>Fusarium</i>Keratitis Associated With Use of a Contact Lens Solution <h3>Context:</h3> <i>Fusarium</i>keratitis is a serious corneal infection, most commonly associated with corneal injury. Beginning in March 2006, the Centers for Disease Control and Prevention received multiple reports of<i>Fusarium</i>keratitis among contact lens wearers. <h3>Objective:</h3> To define the specific activities, contact lens hygiene practices, or products associated with this outbreak. <h3>Design, Setting, and Participants:</h3> Epidemiological investigation of<i>Fusarium</i>keratitis occurring in the United States. A confirmed case was defined as keratitis with illness onset after June 1, 2005, with no history of recent ocular trauma and a corneal culture growing<i>Fusarium</i>species. Data were obtained by patient and ophthalmologist interviews for case patients and neighborhood-matched controls by trained personnel. Available<i>Fusarium</i>isolates from patients' clinical and environmental specimens were genotyped by multilocus sequence typing. Environmental sampling for<i>Fusarium</i>was conducted at a contact lens solution manufacturing plant. <h3>Main Outcome Measures:</h3> Keratitis infection with<i>Fusarium</i>species. <h3>Results:</h3> As of June 30, 2006, we identified 164 confirmed case patients in 33 states and 1 US territory. Median age was 41 years (range, 12-83 years). Corneal transplantation was required or planned in 55 (34%). One hundred fifty-four (94%) of the confirmed case patients wore soft contact lenses. Forty-five case patients and 78 controls were included in the case-control study. Case patients were significantly more likely than controls to report using a specific contact lens solution, ReNu with MoistureLoc (69% vs 15%; odds ratio, 13.3; 95% confidence interval, 3.1-119.5). The prevalence of reported use of ReNu MultiPlus solution was similar between case patients and controls (18% vs 20%; odds ratio, 0.7; 95% confidence interval, 0.2-2.8).<i>Fusarium</i>was not recovered from the factory, warehouse, solution filtrate, or unopened solution bottles; production of implicated lots was not clustered in time. Among 39 isolates tested, at least 10 different<i>Fusarium</i>species were identified, comprising 19 unique multilocus genotypes. <h3>Conclusions:</h3> The findings from this investigation indicate that this outbreak of<i>Fusarium</i>keratitis was associated with use of ReNu with MoistureLoc contact lens solution. Contact lens users should not use ReNu with MoistureLoc.

Variable Responses of Acanthamoeba Strains to Three Multipurpose Lens Cleaning Solutions

A novel method has been developed to compare Acanthamoeba strain differences by testing their susceptibility to multipurpose contact lens cleaning solutions (MPS). This method uses surface-attached amoebae that mimic cells attached to a contact lens. In brief, acanthamoebae were grown on non-nutrient agar plates with Escherichia coli prey. Blocks of agar with cysts or trophozoites (approximately 50 cells) were cut out and transferred to MPS [ReNu MultiPlus; (Bausch & Lomb, Rochester, NY), Complete (Allergan, Irvine, CA), and Opti-Free Express (Alcon, Ft. Worth, TX)] for up to 24 h treatment. After neutralizing in Dey Engley broth (Difco), blocks were washed in amoeba saline and reinoculated onto fresh prey bacteria. Positive growth was indicative of survival. Testing showed that the efficacy of the three MPS was different. Opti-Free was the most effective against cysts, followed by ReNu while Complete was relatively ineffective. Not surprisingly, trophozoites were more susceptible than cysts. Findings for individual MPS complement previous work with other methods. This study has also identified that environmental strains vary in their sensitivity to disinfecting solutions. Overall, Acanthamoeba genotypes T3, T5, and T11 from the environment were more resistant than the T4 isolates from the cornea and beach. This resilience supports previous work on temperature tolerance, in which T3 and T5, and T11 acanthamoebae grew in temperatures up to 41 degrees C. Investigators should therefore consider the strain genotype and its source before embarking on MPS sensitivity testing.

Report on Testing From an Investigation of Fusarium Keratitis in Contact Lens Wearers

Recent reports of disproportionate outbreaks of microbial keratitis caused by Fusarium solani have led to the removal of the Bausch & Lomb multipurpose lens care solution ReNu With MoistureLoc ("MoistureLoc") from the global market. Previous studies have shown an increased risk of contact lens-related corneal infection in connection with overnight wear, noncompliant lens wearing and lens care behaviors, specific treatment regimens, and other patient-related and non-patient-related factors. The purpose of the laboratory evaluations reported in this article were to observe the effects of levels of simulated lens care noncompliance on the antimicrobial efficacy of multipurpose solutions following recent reports of F. solani keratitis. Two multipurpose contact lens care solutions, MoistureLoc and ReNu MultiPlus multipurpose solution ("ReNu MultiPlus"), were tested under conditions that attempted to simulate the possible effect of the noncompliant behaviors reported to Bausch & Lomb as part of the investigation into cases of Fusarium keratitis. Testing conditions included simulated multiple reuse of solutions and evaporation of solutions. The biocidal efficacy of MoistureLoc and other tested solutions was reduced under conditions that simulated the possible impact of solution reuse. Further investigation of MoistureLoc and ReNu MultiPlus suggests that although efficacy with ReNu MultiPlus was maintained across a variety of noncompliant conditions, the MoistureLoc formula could be rendered less effective under certain conditions. Under conditions simulating the possible impact of noncompliance, the MoistureLoc solution showed reduced biocidal efficacy. In contrast, ReNu MultiPlus retained a higher level of biocidal activity under the same conditions.

Biocide Uptake in Contact Lenses and Loss of Fungicidal Activity During Storage of Contact Lenses

With recent outbreaks of Fusarium keratitis related to contact lens wear, studies were conducted to determine the biocide uptake during lens storage, and the resulting effect on antifungal activity of related products. ACUVUE 2 (etafilcon A) soft, hydrophilic contact lenses (group IV) were soaked from 1 hour to 7 days in OPTI-FREE Express and OPTI-FREE RepleniSH multipurpose disinfecting solutions with POLYQUAD (polyquaternium-1) and ALDOX (myristamidopropyl dimethylamine) biocides and multipurpose solutions, Bausch & Lomb ReNu with MoistureLoc (Alexidine), ReNu MultiPlus (polyhexamethylene biguanide [PHMB]), and AMO Complete MoisturePLUS (PHMB). Storage solutions were tested to evaluate the effect of preservative uptake on the residual biocide activity against Fusarium solani. Approximately 30% to 60% of the PHMB and Alexidine were depleted by 6 hours, with comparable loss of antimicrobial activity. Decreasing activity was noted with corresponding decreases in active concentration throughout the course of the evaluation. The POLYQUAD systems retained nearly 100% of the biocide and fungicidal activity and maintained their concentration in the solution. OPTI-FREE Express and OPTI-FREE RepleniSH multipurpose disinfecting solutions maintained fungicidal efficacy after storage of lenses. The Alexidine- and PHMB-based multipurpose solutions tested showed significant uptake of preservative into group IV lenses, resulting in a decrease in the residual activity of the storage solution. The POLYQUAD systems showed a low uptake of biocide and maintained fungicidal efficacy against F. solani.

Use of silicone hydrogel material for daily wear

Silicone hydrogel contact lenses were initially developed to optimise oxygen transmissibility for extended wear use. The concerns with such contact lenses have been their higher elastomeric and hydrophobic characteristics associated with the incorporation of silicone type monomers. The use of silicone hydrogel has most recently been suggested for daily wear to eliminate all hypoxic related problems. The primary aim of the investigation was to test in vivo wetting performance and subjective acceptance of the first silicone hydrogel contact lens developed for daily wear, ACUVUE ® ADVANCE™ with HYDRACLEAR™ (galyfilcon A), compared to a conventional hydrogel contact lens for the same application SofLens ®66 (alphafilcon A). The investigation was a randomised, subject masked bilateral cross over investigation testing of the two contact lens materials over their approved replacement periods (galyfilcon A 2 weeks and alphafilcon A 2 weeks (USA) and 4 weeks (Europe)). In all cases ReNu Multiplus ® lens care system was used. The investigation carried out on 24 contact lens wearers showed that: (i) in vivo wettability was superior for galyfilcon A which had a thicker lipid layer (thin layer incidence: galyfilcon A 54%; alphafilcon A 70–86%, p < 0.05), a thicker aqueous layer (thick layer incidence: galyfilcon A 88%; alphafilcon A 35–64%, p < 0.05) and a more stable tear film (galyfilcon A 7.8 s; alphafilcon A 2 weeks 5.6 s, p = 0.022; 4 weeks 7.4 s, p = 0.276); (ii) for the intended replacement period, comfort was better with galyfilcon A (2 weeks) compared to alphafilcon A (4 weeks) at insertion ( p = 0.001) and, throughout the day (daytime and evening p = 0.008). Contact lenses made from galyfilcon A and replaced two weekly achieved better in vivo wettability than contact lenses made from alphafilcon A and replaced either two and four weekly; the better wettability was associated with an overall better comfort for galyfilcon A.

Multistate Outbreak of Fusarium Keratitis Associated With Use of a Contact Lens Solution

Fusarium keratitis is a serious corneal infection, most commonly associated with corneal injury. Beginning in March 2006, the Centers for Disease Control and Prevention received multiple reports of Fusarium keratitis among contact lens wearers. To define the specific activities, contact lens hygiene practices, or products associated with this outbreak. Epidemiological investigation of Fusarium keratitis occurring in the United States. A confirmed case was defined as keratitis with illness onset after June 1, 2005, with no history of recent ocular trauma and a corneal culture growing Fusarium species. Data were obtained by patient and ophthalmologist interviews for case patients and neighborhood-matched controls by trained personnel. Available Fusarium isolates from patients' clinical and environmental specimens were genotyped by multilocus sequence typing. Environmental sampling for Fusarium was conducted at a contact lens solution manufacturing plant. Keratitis infection with Fusarium species. As of June 30, 2006, we identified 164 confirmed case patients in 33 states and 1 US territory. Median age was 41 years (range, 12-83 years). Corneal transplantation was required or planned in 55 (34%). One hundred fifty-four (94%) of the confirmed case patients wore soft contact lenses. Forty-five case patients and 78 controls were included in the case-control study. Case patients were significantly more likely than controls to report using a specific contact lens solution, ReNu with MoistureLoc (69% vs 15%; odds ratio, 13.3; 95% confidence interval, 3.1-119.5). The prevalence of reported use of ReNu MultiPlus solution was similar between case patients and controls (18% vs 20%; odds ratio, 0.7; 95% confidence interval, 0.2-2.8). Fusarium was not recovered from the factory, warehouse, solution filtrate, or unopened solution bottles; production of implicated lots was not clustered in time. Among 39 isolates tested, at least 10 different Fusarium species were identified, comprising 19 unique multilocus genotypes. The findings from this investigation indicate that this outbreak of Fusarium keratitis was associated with use of ReNu with MoistureLoc contact lens solution. Contact lens users should not use ReNu with MoistureLoc.

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.

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.

Contact Lens Care Products Effect on Corneal Sensitivity and Patient Comfort

To evaluate the possible effect of two leading soft contact lens care products on corneal sensitivity, relative comfort, and superficial corneal staining in adapted disposable soft contact lens wearers. Eight disposable soft contact lens wearers equally divided between habitual users of OPTI-FREE Express Lasting Comfort No Rub formula (Alcon Laboratories, Fort Worth, TX) and ReNu MultiPlus (Bausch & Lomb, Rochester, NY) were enrolled in this crossover study. The habitual lens care product was designated the first crossover period. Patients completed a visual analog scale rating of midday and end-of-day comfort, underwent slitlamp examination for staining, and had corneal sensitivity measured by Cochet-Bonnet esthesiometry before and after being switched to the alternative lens care product. The lens care product used was masked from the investigator. Patients habitually using OPTI-FREE Express reported higher comfort ratings than did patients using ReNu MultiPlus. On crossover, patients who initially used ReNu MultiPlus experienced similar comfort when using OPTI-FREE Express, but OPTI-FREE Express users experienced a substantial decrease in comfort when switched to ReNu MultiPlus. Esthesiometry showed significant differences in average sensitivity in favor of OPTI-FREE Express (P=0.0041). Statistical trends supported observed increases in corneal sensitivity when switching to OPTI-FREE Express and decreased corneal sensitivity when switching to ReNu MultiPlus. ReNu MultiPlus was also associated with slightly more corneal staining. ReNu MultiPlus, a biguanide-based contact lens care product, was associated with decreased comfort during midday and end-of-day periods. ReNu MultiPlus was also associated with significant reduction in relative corneal sensitivity compared to Polyquad-based OPTI-FREE Express. Disturbance to normal corneal sensitivity may play a role in contact lens-related dry eye and discomfort. Further investigation is warranted.

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.

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.

Corneal Staining and Subjective Symptoms With Multipurpose Solutions as a Function of Time

Short-term changes in corneal staining and ocular symptoms were assessed at defined intervals to evaluate combinations of three soft lenses and four multipurpose solutions. A series of pilot studies were conducted over 11 months using a double-masked, randomized, crossover design. Asymptomatic, adapted, daily-wear soft lens users wore group II or IV soft hydrophilic or silicone hydrogel lenses for a maximum period each day. Before wear, new lenses were soaked overnight in one of four multipurpose solutions: Alcon OPTI-FREE Express MPDS, Bausch & Lomb ReNu MultiPlus Multipurpose Solution, CIBA Vision SOLO-Care PLUS Multipurpose Solution, or AMO Complete MoisturePLUS. Subjects rated comfort and ocular symptoms. Corneal staining type and area were evaluated at baseline and after lens removal. Significantly increased extent of corneal staining, defined as the proportion of corneal zones showing staining of grade 1 or more severe, was observed at 1 and 2 hours when subjects wore group II lenses soaked in the polyhexamethylene biguanide-based systems. Significantly increased extent of staining was observed at 2 hours when subjects used silicone hydrogel lenses soaked in regimen 4. When subjects used regimen 1 and wore group II lenses, only a minimal staining response was observed at 1 and 2 hours of wear. Significant symptoms were not correlated with extent of staining. This study design is a promising tool that can discriminate between the performance of different soft lens and multipurpose solution combinations rapidly using small patient samples. With some lens-care product combinations, corneal appearance may vary according to the time of day the patient is examined.

COMPARATIVE CYTOTOXICITY POTENTIAL OF SOFT CONTACT LENS CARE PRODUCTS

ABSTRACTPurpose. To determine the cytotoxicity potential of soft contact lens care products and benzalkonium chloride (BAK) by two colorimetric in vitro assays on an immortalized human corneal epithelial cell line (HCE-T). Methods. Four commercial soft contact lens care solutions were tested at 1:3 dilution in growth medium. The positive controls for cytotoxicity were BAK in Dulbecco's phosphate buffered saline (DPBS) at 10, 5, 2.5, and 1.25 ppm and 1:3 dilution of DPBS as negative control. Cell viability was assayed using a novel tetrazolium compound and an electron coupling reagent (MTS/PES), and by cell membrane integrity using neutral red dye uptake and release (NRUR). Mean spectrophotometric optical density of the test samples was compared to mean optical density of the controls at 24 and 48 hours of exposure to test product. Significance was measured by ANOVA/Tukey HSD test. Results. Cell viability and cell membrane integrity tests were not significantly different between lens care solutions and the negative controls for CIBA Vision SOLOcare™ PLUS, Advanced Medical Optics COMPLETE® Comfort PLUS™, or BAK at 1.25 ppm. Exposure to Bausch and Lomb ReNu MultiPlus®, Alcon OPTI-FREE® Express® with Aldox™, BAK 10, 5, and 2.5 ppm yielded significant reduction in cell viability and membrane integrity compared to negative controls. Discussion. Assays of HCE-T cell viability by MTS/PES, and cell membrane integrity by NRUR cells yielded data that were similar to that previously reported with mouse L929 cells in tests based on the USP Elution Test. For the MTS/PES and NRUR assay methods, the solutions in order of increasing cytotoxicity potential were: SOLOCare = COMPLETE Comfort Plus < ReNu < < OPTI-FREE® Express® with Aldox.