Anatomy of a regimen: consideration of multipurpose solutions during non-compliant use

Activity of multipurpose contact lens solutions against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans biofilms

INTRODUCTION

The use of contact lenses has progressively increased around the world, thereby increasing the risk of complications. The most serious complication is microbial keratitis (corneal infection) that can progress to a corneal ulcer.

METHODS

Fourteen multipurpose contact lens solutions were tested on mature biofilms comprising Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans, using the minimum disinfection times recommended by the manufacturers. The biofilm was induced in the lens case, and 24 h later, the solutions were added. Activity against planktonic and sessile cells was evaluated and quantified as colony forming units per millilitre. The minimum concentration for biofilm eradication was defined as a 99.9% reduction in viable cells.

RESULTS

Although most solutions exhibited activity against planktonic cells, only five of the 14 solutions produced a significant reduction in the S. marcescens biofilm. No solution achieved the minimal biofilm eradication of S. aureus, P. aeruginosa and C. albicans.

CONCLUSION

Multipurpose contact lens solutions provide greater bactericidal and/or fungicidal activity on planktonic cells than biofilms. The minimal eradication biofilm concentration was only achieved for S. marcescens.

The impact of patient behaviour and care system compliance on reusable soft contact lens complications

Reusable soft daily wear contact lenses (CLs) remain popular and were fit to just over half of all wearers in the most recent international CL prescribing survey. Unlike daily disposable CLs, reusables require cleaning and disinfecting after every use, along with storage in a CL case. These additional requirements add a number of steps to the daily wear and care routine, increasing the opportunities for CL wearers to exhibit non-compliant behaviour. The impact of non-compliance ranges from poor lens comfort through to potentially sight-threatening infective keratitis. The coronavirus pandemic has refocused the profession on the importance of hand hygiene in particular, and the need for promoting safe CL wear in general. This review summarises typical non-compliant behaviour related to reusable CLs, and examines strategies and opportunities to better support wearers. Patient education has a central role in encouraging compliant behaviour, although patient recall of information is low, and personal belief systems may result in continuation of non-compliant behaviour despite awareness of the risks. CL care solutions are required for the daily disinfection of lenses, however misuse of multipurpose solutions (MPS) and hydrogen peroxide (H₂O₂)-based care systems can challenge their ability to be fully efficacious. Standard efficacy testing is reviewed, with consideration of how well current protocols model real-world use of CL solutions. Although some recommendations are in place for the inclusion of additional variables such as lens cases, CL materials, organic soil and efficacy against Acanthamoeba, opportunity still exists to reevaluate global standards to ensure consistency of testing in all markets. Finally, potential future innovations are discussed which may further support increased safety in reusable lens wear through novel antimicrobial additions to both CL materials and cases.

[Continuous anti-glaucoma drug therapy as a risk factor of dry eye]

A preservative is a mandatory component of the eye drops designed to prevent microbial contamination in an opened bottle. Most of the preservative agents are either detergents, or oxidants; the most widely used and well-studied preservative - benzalkonium chloride - is a detergent. Due to regular usage of glaucoma eye drops, cytotoxic impact of the preservatives on anterior eye surface is considered the principal cause of its pathology, which leads to a decrease in quality of life. The high cost of preservative-free pharmacological forms and the complicated process of developing new preservatives make the usage of eye drops with minimal required concentration of preservative agent and a moistening component a good compromise. The most commonly utilized moistening component is polyvinyl alcohol - synthetic polymeric hydrogel, which is also used in artificial tears and bioengineering.

The comparison of antimicrobial effectiveness of contact lens solutions

PURPOSE

The aim of this study was to compare the effects of widely used multipurpose contact lens solutions against Staphylococcus aureus and Pseudomonas aeruginosa, in addition to cystic and trophozoite forms of Acanthamoeba castellanii and A. polyphaga, that cause microbial keratitis.

METHODS

Three multipurpose solutions were tested: SOLO-care, ReNu, and Opti-Free Express. The test solutions were challenged with P. aeruginosa (ATCC 27853) and S. aureus (ATCC 2913) based on the ISO stand-alone and regiment test procedure for disinfecting products, A. polyphaga (ATCC 30871) and A. castellanii (1501/1A) cystic and trophozoite forms. Multipurpose solutions were sampled for surviving microorganisms at manufacturer's minimum recommended disinfection time. The number of viable organisms was determined, and log reductions were calculated.

RESULTS

ReNu and SOLO-care resulted in a reduction greater than the required mean 3.0 logarithmic reduction against S. aureus, and SOLO-care and Opti-Free Express resulted in a reduction more than the required mean 3.0 logarithmic reduction against P. aeruginosa. Against the cystic and trophozoite forms of A. castellanii, the log reduction provided by SOLO-care was 1.01 and 1.31 log, respectively. ReNu provided a 0.83 log reduction of the cystic form and a 1.21 log reduction of the trophozoite form. Using Opti-Free Express, the log reduction for both forms was 1.31. SOLO-care led to a 0.61 log reduction of the cystic form of A. polyphaga and a 1.01 log reduction of the trophozoite form. ReNu provided a 0.41 log reduction of the cystic form and a 4.99 log reduction of the trophozoite form. Opti-free Express resulted in a 0.89 log reduction of the cystic form and a 3.11 log reduction of the trophozoite form.

CONCLUSIONS

Multipurpose contact lens solutions using similar regimens can show different disinfection abilities.

A comparison of the ability of three common contact lens solutions with different constituents to inhibit growth of <i>Staphylococcus aureus</i>

Background: Staphylococcus aureus is a common commensal on skin and mucosal surfaces; its contact with the eye may cause a variety of ocular inflammations and infections such as blepharitis, conjunctivitis and keratitis, amongst others. Soft contact lenses provide perfect conditions for the breeding of certain pathogens, and disinfecting solutions for contact lenses are therefore of utmost importance. These solutions should be effective in inhibiting the growth of a variety of pathogens to protect the user from ocular infections.Aim: To highlight the need for clinicians to be aware of the effects of various recommended disinfecting contact lens solutions.Method: Three popular disinfecting contact lens solutions readily available in South Africa were chosen. These and a control solution (saline) were prepared and inoculated with S. aureus to evaluate the antimicrobial efficacy of each solution. The primary stand-alone test was used to evaluate the solutions according to the ISO standard specifically for this purpose.Results: The test results indicated that two of the solutions met the ISO standards; the third failed. Of the two that passed the test, only one showed the required 3-log reduction after 30 minutes, as per the ISO standard, although this solution is marketed as a ’10 minute system’.Conclusion: It is important for clinicians to be aware of the complications that may be caused by contaminated solutions, and patients should be warned about the effects thereof. To ensure healthy eyes for our patients, sufficient knowledge regarding the efficacy of recommended multipurpose solutions is necessary. Solutions that meet ISO standards promote good ocular health and ensure sufficient cleaning and disinfecting of contact lenses.

The use of daily disposable lenses in problematic reusable contact lens wearers

PURPOSE

Replacing soft contact lenses (CLs) on a daily basis brings a number of advantages, most notably, reduced exposure to deposits, disinfectants, allergens, and other contaminants. This retrospective study estimated the prevalence of problems in current wearers of reusable soft CLs and tested the effect of refitting "problem" patients with daily disposable (DD) hydrogel lenses.

METHODS

Prevalence was estimated from 398 current reusable CL wearers for: frequent/constant discomfort or dryness, ≥2 h of uncomfortable wear, ≥grade 2 conjunctival hyperaemia (0-4), or ≥grade 3 corneal staining (0-15). In the second part of the study, 217 reusable CL wearers classified as problem patients were randomly refitted with DD lenses manufactured from one of two materials: etafilcon A (n=96) or nelfilcon A (n=121) and reassessed 1 week later.

RESULTS

Thirty-nine percent (154/398) had some qualifying criterion: reduced comfortable wearing time (CWT), 20%; dryness, 20%; irritation, 5%; corneal staining, 8%; and hyperaemia, 7%. After refitting with DDs, the prevalence of reduced CWT was decreased from 65% to 51% (P=0.0039), dryness from 60% to 41% (P < 0.0001) and corneal staining from 28% to 21% (P=0.04). There was no significant change in the prevalence of irritation, or hyperaemia. Some differences were noted between the two lens materials.

CONCLUSIONS

A high proportion of reusable soft lens wearers encounter clinically relevant signs or symptoms with their current CLs. This study provides evidence that refitting with DD lenses is a useful strategy for alleviating some of the common problems of CL wear.

Overview of the [corrected] travoprost /timolol BAK-free fixed combination

INTRODUCTION

Glaucoma is the second leading cause of blindness globally, representing a significant public health concern. More than 60 million people are affected by glaucoma worldwide; as this population ages, the number is expected to increase. Glaucoma is a collection of heterogeneous diseases sharing common clinical characteristics. The goal of treatment is to prevent significant visual dysfunction through reduction of intraocular pressure (IOP).

AREAS COVERED

This is a review of the current literature about combination therapeutic regimens for the reduction of IOP, focusing on the risk : benefit profile of a fixed-combination therapy using travoprost and timolol.

EXPERT OPINION

Since the debut of prostaglandin analogues in the 1990s, only modest innovation has occurred in glaucoma pharmacology. A growing body of research has established that the preservative benzalkonium chloride (BAK) might not be the benign contributor expected of excipient ingredients. Thus, BAK-free treatments were developed, with the goal of IOP reduction without furthering ocular surface disease symptoms. The BAK-free travoprost/timolol combination represents an important addition to glaucoma medication options and may fill an unmet need in this therapeutic arena.

A new method for evaluation of compatibility of contact lenses and lens cases with contact lens disinfecting solutions

PURPOSE

The purpose of this article is to describe new methodology, antimicrobial efficacy endpoint methodology to determine compatibility of contact lens solutions, lens cases and hydrogel lenses for disinfection (AEEMC), to evaluate the effect of a contact lens and a lens case on disinfection efficacy, and to present the ring test used to justify the use of the method in multiple laboratories.

MATERIALS AND METHODS

A prototype solution containing chlorhexidine as the disinfecting agent and four representative lens types (group I and IV hydrogels and two silicone hydrogels) were used in these ring tests. Five laboratories participated in the chemical and microbiologic analyses. The residual chlorhexidine in lens cases containing the contact lenses was determined using high-performance liquid chromatography; uptake by the lenses was then determined by extrapolation. For the microbiologic part of the study, a contact lens was placed in the well of the lens case, inoculated at 10 to 10 cfu (colony forming units) per lens with microorganisms in 10% organic soil. The microorganisms, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, Candida albicans, and Fusarium solani, were prepared as in International Organization for Standardization (ISO) 14729. After a 3- to 10-min exposure time, the prototype solution was dispensed into each well. Aliquots of the inoculated solutions were removed at 4 and 24 hrs and 7 and 30 days and cultured in neutralizing media for determination of survivors; lenses were also cultured for survivors.

RESULTS

Chemical uptake data confirmed the differences observed in kill of the challenge organisms according to lens type. It was observed that the culturing of the solution provided adequate data to show the effect of a lens on disinfection efficacy of a lens care product. The findings of the ring test indicated that the separate culturing of the contact lenses is not necessary for routine assessment.

CONCLUSIONS

The methodology in the November 12, 2008, draft standard (AEEMC), meets the stated objective of demonstrating the effect of a contact lens on the disinfection efficacy of a simulated lens care product. This method, used in combination with the methodology in ISO 14729, should provide for a more robust evaluation of applicable contact lens care disinfecting products.

Ophthalmic preservatives: focus on polyquaternium-1

INTRODUCTION

Ophthalmic preservatives, such as polyquaternium-1 (PQ-1), are critical for the inhibition of growth of microbial contaminants in multi-dose bottles of topical medications. These antimicrobial agents must have a high efficacy against pathogenic organisms, while maintaining a favorable tolerability and safety profile.

AREAS COVERED

This review focuses on the ophthalmic preservative PQ-1. For comparison purposes, the most commonly used preservative, benzalkonium chloride (BAK), is also discussed. This survey focuses primarily on data collected during the past 10 years.

EXPERT OPINION

Effective drug delivery requires more than just an active ingredient that achieves its desired biological effect on end-target tissues. In addition, drugs must be stable in the containers that they are stored in, and must possess minimal undesired local and systemic side effects that can cause patients to decrease their adherence. In addressing these concerns, specifically in topical ophthalmic drops, one must take into account the active ingredients, vehicle components and preservatives. Medications with fewer adverse effects may lead to enhanced adherence to therapy; therefore, the induction of such adverse outcomes must be considered by physicians when treating patients with chronic ocular disease. Although BAK will continue to be used in ophthalmic medications, due to its familiarity and compatibility with a broad range of topical ocular formulations, PQ-1 is certainly a viable alternative in the preservative formulary armamentarium.

Impact of a rinse step on protein removal from silicone hydrogel contact lenses

PURPOSE

To determine the impact of the rinse step in "no rub" contact lens care systems relative to its ability to assist in removing loosely associated and bound tear film proteins from a worn silicone hydrogel lens.

METHODS

After informed consent, subjects were fitted with lotrafilcon B contact lenses (CIBA Vision). If the fit was acceptable, subjects were asked to wear the lenses on a daily wear basis for 5 (+2, -0) days for an outcome visit. Subjects were instructed to use AQuify Multi-Purpose Disinfecting Solution (CIBA Vision) following the manufacturer's "no rub" instructions. At the outcome visit, contact lenses were then collected by a gloved examiner, with a sterile metal forceps, who rinsed the right lens but did not rinse the left lens on removal from the eyes. Protein was extracted with a 50:50 0.2% trifluoroacetic acid-acetonitrile solution and quantified using a Bradford analyses.

RESULTS

Twenty contact lens wearers were enrolled in this study. For the non-rinsed lenses, the first extraction yielded 13.4 +/- 9.2 microg/lens of protein, whereas the second extraction yielded 5.8 +/- 2.8 microg/lens of protein. For the rinsed lenses, the first extraction yielded an average of 3.0 +/- 1.9 microg/lens of protein, whereas the second extraction yielded an average of 4.0 +/- 2.3 microg/lens. Repeated measures analysis of variance showed a significant interaction (F-statistic = 18.9, p < 0.0001) between the rinse of a lens and extraction number.

CONCLUSIONS

Rinsing a contact lens after removal from the eye removes well more than one-half of the protein associated with it. Further, to biochemically recover all protein from a silicone hydrogel lens, it may be important to perform more than one chemical extraction from it.

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

PURPOSE

To evaluate subjective symptoms and clinical signs in silicone hydrogel contact lens wearers with three different multipurpose solution (MPS) lens care regimens.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.

Molecular characterization, biofilm analysis and experimental biofouling study of Fusarium isolates from recent cases of fungal keratitis in New York State

BACKGROUND

To characterize Fusarium isolates from recent cases of fungal keratitis in contact lens wearers, and to investigate fungal association with MoistureLoc solution.

METHODS

We studied six fungal isolates from recent cases of keratitis in New York State. The isolates were characterized by nucleotide sequencing and phylogenetic analyses of multiple genes, and then typed using minisatellite and microsatellite probes. Experimental fungal biofilm formation was tested by standard methods. MoistureLoc solutions were tested in biofouling studies for their efficacy in elimination of Fusarium contamination.

RESULTS

Fusarium solani--corneal ulcers (2 isolates), lens case (1 isolate), and F. oxysporum--corneal ulcer (1 isolate), eye (1 isolate), were recovered from five patients. An opened bottle of MoistureLoc solution provided by a patient also yielded F. solani. Two distinct genotypes of F. solani as well as of F. oxysporum were present in the isolated strains. Remarkably, F. solani strains from the lens case and lens solution in one instance were similar, based on phylogenetic analyses and molecular typing. The solution isolate of F. solani formed biofilm on contact lenses in control conditions, but not when co-incubated with MoistureLoc solution. Both freshly opened and 3-month old MoistureLoc solutions effectively killed F. solani and F. oxysporum, when fungal contamination was simulated under recommended lens treatment regimen (4-hr). However, simulation of inappropriate use (15-60 min) led to the recovery of less than 1% of original inoculum of F. solani or F. oxysporum.

CONCLUSION

Temporary survival of F. solani and F. oxysporum in MoistureLoc suggested that improper lens cleaning regimen could be a possible contributing factor in recent infections.

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

OBJECTIVES

To assess and compare the cytotoxicity and antimicrobial activity of six multipurpose disinfecting contact lens solutions (MPDS).

METHOD

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).

RESULTS

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.

CONCLUSIONS

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.