Contact Lens Storage Research Articles

Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses.

Acanthamoeba spp. are amphizoic amoebae that are widely distributed in the environment and capable of entering the human body. They can cause pathogenic effects in different tissues and organs, including Acanthamoeba keratitis (AK), which may result in a loss of visual acuity and blindness. The diagnostics, treatment, and prevention of AK are still challenging. More than 90% of AK cases are related to the irresponsible wearing of contact lenses. However, even proper lens care does not sufficiently protect against this eye disease, as amoebae have been also found in contact lens solutions and contact lens storage containers. The adhesion of the amoebae to the contact lens surface is the first step in developing this eye infection. To limit the incidence of AK, it is important to enhance the anti-adhesive activity of the most popular contact lens solutions. Currently, silver nanoparticles (AgNPs) are used as modern antimicrobial agents. Their effectiveness against Acanthamoeba spp., especially with the addition of plant metabolites, such as tannic acid, has been confirmed. Here, we present the results of our further studies on the anti-adhesion potential of tannic acid-modified silver nanoparticles (AgTANPs) in combination with selected contact lens solutions against Acanthamoeba spp. on four groups of contact lenses. The obtained results showed an increased anti-adhesion activity of contact lens solutions in conjunction with AgTANPs with a limited cytotoxicity effect compared to contact lens solutions acting alone. This may provide a benefit in improving the prevention of amoebae eye infections. However, there is still a need for further studies on different pathogenic strains of Acanthamoeba in order to assess the adhesion of the cysts to the contact lens surface and to reveal a more comprehensive picture of the activity of AgTANPs and contact lens solutions.

Compliance versus Risk Awareness with Contact Lens Storage Case Hygiene and Replacement.

Compliance with hygiene and replacement of contact lens (CL) storage cases is key to avoid CL contamination and anterior ocular surface complications. However, compliance levels with these accessories remain low, even in patients with awareness of the risk associated with noncompliance. This study aimed to determine level of compliance with common practices regarding CL storage case hygiene and replacement, type of information provided by practitioners, and risk perception. An ad hoc self-reported survey was used to collect demographic and CL wear details, compliance with storage case care, type of received information, and risk perception (in a 1-to-5 scale). Inferential statistics explored the relationship of demographic details and type of received information with compliance and risk perception. Nondaily disposable wearing participants returned 299 completed surveys, with a median age of 24 years (76.9% females). Monthly replacement silicone hydrogel CLs and multipurpose solutions were predominant. Self-reported compliance with storage case care was poor, with 19.1% of respondents never cleaning their cases, 68.6% exposing them to tap water, and 26.4% failing to replace them within 6 months of acquisition. Two-thirds of respondents received specific information on case maintenance, mainly in oral form. Perceived risk associated with poor-compliance practices was high (median values of 4 and 5), and increased with educational level (P = .02, regarding handwashing; P = .03, regarding case hygiene), with years of CL wear experience (P < .001, regarding handwashing), in those patients provided with specific information on CL case care (P = .01, regarding case replacement). Compliance with CL storage case hygiene and replacement was generally poor, although awareness of risk associated with noncompliance was high and influenced by factors related to demographic details, CL experience, and patient-practitioner communication. Strategies must be explored to increase risk awareness through education because this may lead to better compliance practices.

Survey of hygiene, behaviours, and awareness regarding contact lens wear with conventional and novel questions

ABSTRACT Clinical relevance: Contact lens (CL) compliance studies are beneficial to identify potential risks, take necessary measures, and issue warnings on time. Background: Understanding CL compliance is crucial to ensure that individuals maintain healthy and appropriate CL wear. The present study aims to assess knowledge and awareness about soft CLs; the degree of non-compliance among soft CL wearers; and the associations of these with demographic features. Methods: A comprehensive questionnaire composed of 44 questions was used to assess the demographic characteristics, hygiene care, habits, knowledge, opinions, awareness and experiences of 109 soft CL wearers. The survey was conducted between September 2019 and March 2020. Results: The mean non-compliance rates were: 35.4% and 11.2% for hand-washing and hand-drying; 77.8% for rubbing/rinsing of the CLs; and 37.0%, 50.5%, and 31.6% for swimming, showering, and overnight sleeping with the CLs in, respectively. Women were more compliant in manual cleaning and rinsing of the CL storage cases with lens solution (p = 0.037). Swimming behaviour with inserted CLs was significantly high among CL users with over 5 years of experience (p = 0.03). Additionally, 85% of the wearers generally found the soft CLs comfortable, and 69.8% found the cost of the soft CLs reasonable. Over 90% of the wearers spent between 0 to 5 min per day to insert and remove the soft CLs. Conclusion: Women presented with more frequent CL use, and were significantly more compliant in terms of cleaning the CL storage cases. Regardless of gender, the non-compliance of swimming with inserted CLs was significantly high among CL wearers with over five years of experience. A majority of the results of the investigated non-compliances did not depend on gender, income level, age-group, duration of CL use, and education level.

Microbiome analysis of contact lens care solutions and tear fluids of contact lens wearers: Possible involvement of streptococcal antigens in allergic symptoms related to contact lens wear.

The present study elucidated the pathogenesis of allergic symptoms (AS) related to contact lens (CL) wear by assaying CL care solutions in lens storage cases and tears from subjects with AS using molecular biology techniques. A total of 15 CL storage cases were collected from subjects with AS (n=9) and healthy, asymptomatic control CL wearers (n=6). Bacterial populations in CL care solutions and tears were assayed by culture and 16S rDNA sequencing. Histamine levels in tears were measured by high-performance liquid chromatography. Western blot analysis was performed to identify the bacteria recognized by tear IgE from subjects with AS. No significant differences were found in the culture results between the subjects with AS and asymptomatic subjects. Histamine was detected in 2 subjects with AS. Meta-16S rDNA sequencing identified a cluster of 4 subjects with AS that were distinguished from others by principal coordinate analysis. Detailed population analysis revealed that the abundance of Gram-positive bacteria in the microbiomes of CL care solutions used by the subjects with AS were higher than those of asymptomatic subjects (42.24±9.47 vs. 16.85±22.76% abundance). Among these, Streptococcus was the dominant genus (12.1-18.3% abundance). Tear microbiome analysis revealed that the abundance of Streptococcus in the subjects with AS was significantly higher than that in other subjects (19.02±5.50 vs. 3.08±3.35%, P<0.01). Western blot analysis demonstrated that the tear IgE in all subjects with AS reacted with Streptococcus (100%), but not with Staphylococcus. On the whole, these results provide novel insight into the pathogenesis of AS and identify Streptococcus as an important factor in AS associated with CL wear.

Molecular Bioburden of the Lens Storage Case for Contact Lens-Related Keratitis.

To elucidate the bioburden of a lens care system in patients with contact lens (CL)-related keratitis. In this prospective case-control study, the CL storage case was used as the target of bioburden assessment. Participants were CL wearers with (n = 26) or without (n = 24) keratitis in southern Taiwan. The case fluid sample was consecutively collected and assessed using a dot hybridization assay (DHA) for bioburden assessment. The DHA was composed of 3 universal bacterial probes for detecting all bacteria, genus-specific probes for Pseudomonas and Acinetobacter, and 1 probe for Acanthamoeba. The receiver operating characteristic curve was used to analyze the differentiating performance of a probe. The storage case bioburden was significantly higher in those with CL-related keratitis than in control subjects; patients with CL-related keratitis had stronger standardized signals in all universal bacterial probes. Moreover, in the cases of these patients, the bioburden was significantly heavier in confirmed infectious keratitis than in presumed noninfectious keratitis. Receiver operating characteristic analysis showed that stronger signals in all 3 universal bacterial probes and the Pseudomonas probe might suggest that the wearers have infectious keratitis. Only the storage case of the Acanthamoeba keratitis case showed positive detection by the Acanthamoeba probe. A heavier bioburden in the lens storage case was associated with a higher risk of CL-related keratitis and infectious keratitis. Inappropriate maintenance of the CL will lead to microbial contamination and transfer the pathogen onto the ocular surface causing keratitis accordingly. The DHA assessment for the lens storage case might provide an alternative way to differentiate infectious from noninfectious CL-related keratitis.

Pilot study on the clinical performance of three different multipurpose solutions with a silicone hydrogel contact Lens

Method: The volume required for each step of a daily contact lens cleaning and storage regime were calculated for: COMPLETE EasyRub (CER),OPTI-FREERepleniSH (OFR) andAll InOneLite (AIL). The volumes of solution used in each regime step were then combined for a range of daily regime types, and the number of days of possible lens care for each notional monthly allowance (NMA) were then calculated. Results: For a simple daily regime of placing lenses in a case filled to the designated line with solution, manymore than 30 days of solution use was possible for each solution. With an additional step of lens rubbing with a one sided 1s rinse and case rinsing, 23.1, 20,8 and 22.7 days per NMA were possible for CER, OFR and AIL respectively. If the rinse was increased to a 5s per side rinse (according to the instructions of OFR and CER) then only 8.8, 7.1 and 8.9 days per NMA were possible. Conclusions: Solutionmulti-packs positioned for threemonths’ use provide sufficient solution if no rub and rinse step is advocated, or if a short lens rinse is prescribed. However, such packs do not provide enough solution if a longer (5s) rinse is prescribed. Given the importance of compliance to contact lens wearers, these findings should be considered by clinicians when supplying contact lens solutions.

Risk Factors for Moderate and Severe Microbial Keratitis in Daily Wear Contact Lens Users

To establish risk factors for moderate and severe microbial keratitis among daily contact lens (CL) wearers in Australia. A prospective, 12-month, population-based, case-control study. New cases of moderate and severe microbial keratitis in daily wear CL users presenting in Australia over a 12-month period were identified through surveillance of all ophthalmic practitioners. Case detection was augmented by record audits at major ophthalmic centers. Controls were users of daily wear CLs in the community identified using a national telephone survey. Cases and controls were interviewed by telephone to determine subject demographics and CL wear history. Multiple binary logistic regression was used to determine independent risk factors and univariate population attributable risk percentage (PAR%) was estimated for each risk factor. Independent risk factors, relative risk (with 95% confidence intervals [CIs]), and PAR%. There were 90 eligible moderate and severe cases related to daily wear of CLs reported during the study period. We identified 1090 community controls using daily wear CLs. Independent risk factors for moderate and severe keratitis while adjusting for age, gender, and lens material type included poor storage case hygiene 6.4× (95% CI, 1.9-21.8; PAR, 49%), infrequent storage case replacement 5.4× (95% CI, 1.5-18.9; PAR, 27%), solution type 7.2× (95% CI, 2.3-22.5; PAR, 35%), occasional overnight lens use (<1 night per week) 6.5× (95% CI, 1.3-31.7; PAR, 23%), high socioeconomic status 4.1× (95% CI, 1.2-14.4; PAR, 31%), and smoking 3.7× (95% CI, 1.1-12.8; PAR, 31%). Moderate and severe microbial keratitis associated with daily use of CLs was independently associated with factors likely to cause contamination of CL storage cases (frequency of storage case replacement, hygiene, and solution type). Other factors included occasional overnight use of CLs, smoking, and socioeconomic class. Disease load may be considerably reduced by attention to modifiable risk factors related to CL storage case practice.

The Impact of Cellular Debris on Pseudomonas aeruginosa Adherence to Silicone Hydrogel Contact Lenses and Contact Lens Storage Cases

To evaluate neutrophil-enhanced Pseudomonas aeruginosa (PA) biofilm formation on silicone hydrogel contact lenses and to determine the effect of epithelial biodebris on PA adherence in contact lens storage cases. A fully invasive PA corneal isolate stably conjugated to green fluorescent protein was used. Unworn lotrafilcon A contact lenses were incubated at various ratios of PA to polymorphonuclear neutrophil (PMN) for 24 hours at 37°C. Lens-associated PA was evaluated using laser scanning confocal microscopy and nonviable PA were visualized using propidium iodide. Viable bacteria were enumerated by colony-forming unit (CFU) analysis. For acute epithelial cell studies, PA viability was determined after coincubation with freeze-thaw epithelial cell lysates in 96-well polystyrene plates. Levels of residual cellular debris and bacterial viability were further assessed in used contact lens storage cases. Laser scanning confocal microscopy demonstrated that cotreatment with PMA-stimulated neutrophils increased PA adherence over 24 hours to lens surfaces with a striking alteration of PA architecture. Propidium iodide staining showed that the adherent bacteria consisted of a mixture of viable and nonviable PA; a PMN-associated increase in viable PA was confirmed by CFU (PA:PMN 0.1:1, P = 0.025; PA:PMN 1:1, P = 0.005). Acute epithelial cell debris studies revealed a significant increase in viable PA in 96-well plates in the presence of epithelial freeze-thaw lysates (PA:debris 1:1, P = 0.002; PA:debris 100:1, P = 0.002). Crystal violet staining of used lens storage cases revealed residual cellular debris at all time points, which was independent of microbial contamination; all lens cases used for periods of 9 months or more were uniformly associated with high levels of viable microorganisms. These results demonstrate that prolonged corneal inflammation with the presence of PMNs when confronted with simultaneous PA challenge in extended contact lens wear has the potential to stimulate biofilm formation on silicone hydrogel contact lenses. These findings further suggest that a persistent buildup of extracellular debris in lens storage cases may contribute to the heavy biofilms reported on these surfaces.

Biocidal Efficacy of Silver-Impregnated Contact Lens Storage Cases In Vitro

Silver-impregnated contact lens (CL) storage cases are designed to reduce microbial contamination during use, but there are limited data on their effectiveness. This study evaluated early antimicrobial activity of silver-impregnated CL cases and silver-release characteristics in vitro. Three silver-impregnated CL storage cases-MicroBlock (CIBA Vision, Atlanta, GA), i-clean (Sauflon Pharmaceuticals Ltd., London, UK), and Nano-case (Marietta Vision, Marietta, GA)-were evaluated. Test organisms included the ISO14729 panel and two clinical isolates, Delftia acidovorans and Stenotrophomonas maltophilia. Each well of the case was challenged with 2 mL of the organism in phosphate-buffered saline at 10(3), 10(4), 10(5), and 10(6) CFU/mL. Survivors were recovered after 6, 10, and 24 hours' incubation at 25°C. Inductively coupled plasma mass spectrometry was used to quantify the release of silver from the cases for similar incubation conditions and for time points up to 28 days. Significant differences in antimicrobial activity were observed between cases (P ≤ 0.001). Activity was apparent only after 24 hours. MicroBlock showed the highest activity against Pseudomonas aeruginosa (2.4 ± 0.5 log reduction at 10(6)), Serratia marcescens (3.3 ± 0.9 log reduction at 10(6)), D. acidovorans (2.8 ± 0.1 log reduction at 10(3)), and Fusarium solani (0.5 ± 0.2 at 10(3)). The i-clean case was most effective against Staphylococcus aureus (5.4 ± 1.1 log reduction), whereas Nano-case showed the greatest activity against S. maltophilia (0.2 ± 0.3 log reduction at 10(3)). MicroBlock was the only case to demonstrate silver release over 28 days. Current silver-impregnated CL storage cases show variation in their in vitro antimicrobial activity. Broadly, the MicroBlock case demonstrated robust activity against most Gram-negative bacteria, whereas the i-clean case was more effective against S. aureus. Silver-release data suggest different modes of action for different cases.

Molecular genetic investigations of contaminated contact lens storage cases as reservoirs of Pseudomonas aeruginosa Keratitis

To elucidate the reservoirs of Pseudomonas aeruginosa keratitis associated with contact lens (CL) wear by using a molecular genotyping method. Ten P. aeruginosa isolates obtained from two young adult patients with infectious keratitis associated with CL wear were studied. These were isolated from corneal specimens, conjunctival swabs, discharges, CL storage cases, and the living environment of the two patients. Species identification was performed with an Oxi/Ferm Tube II system using well-separated colonies on MacConkey and NAC agar plates. We employed molecular genotyping by pulsed-field gel electrophoresis. We isolated three (one each from a corneal scraping, discharge, and a CL storage case) P. aeruginosa samples from patient 1, and seven (one each from the conjunctival swab, CL storage case, and the patient's fingers, and four from the patient's room) from patient 2. Pseudomonas aeruginosa of environmental origin could not be obtained from the house of patient 1. The genotypes of two P. aeruginosa isolates, from corneal scraping and discharge, were identical to that of the isolate from the CL storage case belonging to patient 1. In patient 2, the isolates from the eye and the CL storage case showed the identical genotype, which was different from those of the environmental isolates. Our results suggest that the causative P. aeruginosa strains in cases of infectious keratitis associated with CL wear originate in contaminated CL storage cases. However, it is still unclear whether the environmental strains in the patients' houses also cause keratitis.

Poster 23: Loss of Biocidal Activity During Storage of Contact Lenses

Poster 23: Loss of Biocidal Activity During Storage of Contact Lenses

Ulcerative keratitis associated with contact lens wear

To review the microbiological profile of ulcerative keratitis associated with contact lens (CL)-wear, 35 patients with culture-proven CL-associated microbial keratitis were studied between September 1999 and September 2002. Corneal scrapes and CL-care products were collected and were subjected to microbiological evaluation. Gram-negative bacilli alone were recovered from the corneal scrapes of all 35 (100%) patients, all 70 (100%) CL storage case wells and also from CL-care solution of six (17.14%) of the 35 patients. There was a significantly higher number of Pseudomonas aeruginosa (71.43%) isolated from eyes with CL-related keratitis than other bacterial isolates (28.57%) (P<0.001). Microbial contamination of CL storage cases was a great risk for gram-negative bacterial infection among soft CL-wearers.

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.

In vitro acanthamoebicidal activity of a killer monoclonal antibody and a synthetic peptide

To evaluate the in vitro microbicidal activity against Acanthamoeba castellanii of a murine monoclonal anti-idiotypic antibody (KTmAb) and a synthetic killer mimotope (KP), which mimic a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity through interaction with specific cell wall receptors, mainly constituted by beta-glucans. Amoebicidal activity was investigated after incubation of trophozoites under different experimental conditions with laminarinase, KTmAb, KP and a scrambled decapeptide (SP). To confirm the specific interaction of KP with beta-glucans, the experiments were also carried out in the presence of laminarin (beta1-3-glucan) or pustulan (beta1-6-glucan); both glucan molecules were co-incubated with KP or SP. KTmAb and KP exhibited a time-dependent killing activity, in comparison with SP or heat-inactivated KTmAb; this activity was completely abolished by pre-incubation with laminarin, but not by pustulan. Notably, in vitro amoebicidal activity was observed in the presence of laminarinase, an enzyme that specifically hydrolyses beta-glucans. Furthermore, KP specifically inhibited the growth of Acanthamoeba on infected contact lenses and the remaining adherent KP-treated trophozoites appeared strongly damaged. The results indicate that the expression of beta1-3-glucan receptors in the cell membrane is probably modulated during cell growth of A. castellanii and is critical for the killing activity of KT-like molecules. Our data confirm the broad antimicrobial spectra of KTmAb and KP, emphasize the crucial role of beta1-3-glucan in microbial physiology and suggest the potential use of KTmAb and KP in the prevention and therapy of Acanthamoeba infections or in preventing Acanthamoeba contamination during storage of contact lenses.

The Biochemistry of Film-Forming Molecules Producing a Lipid Membrane that Facilitates the Restoration of the Preocular Tear Film

THE OCULAR SURFACE / JANUARY, 2005, VOL. 3, NO. 1 / SUPPLEMENT S67 THE BIOCHEMISTRY OF FILM-FORMING MOLECULES PRODUCING A LIPID MEMBRANE THAT FACILITATES THE RESTORATION OF THE PREOCULAR TEAR FILM. Thomas Glonek, Jack V. Greiner, Donald R. Korb. Midwestern University, Chicago, IL; Department of Ophthalmology, Harvard Medical School, Schepens Eye Research Institute, Boston, MA; 2 Korb & Associates, Boston, MA. Purpose. The majority of the millions of dry eye patients in the USA suffer from lipid layer deficiency in the preocular tear film. The purpose is to describe the detailed biochemistry and evolution of a lipid-membraneforming solution that restores the preocular tear film. Conceptual Development. Foundation of concept based on the following: (1) the understanding that, of all the dry eye syndromes, those with lipid layer deficiency from meibomian gland dysfunction comprise the greatest percentage of dry eye sufferers, (2) the question of how to produce an artificial tear that restores the lipid layer began with lecithin, (3) the understanding that lecithin from natural sources is comprised of a class of phospholipids and not just glycerol 3-phosphorylcholine, and (4) the discovery that it is interfacial molecules that hold the key to building a thick neutral superficial oily layer. Results. (1) The biochemical construction by interfacial molecules produces an interfacial layer that has the chemical characteristics of a strong membrane. (2) The production of this biochemical membrane supports an overlying neutral lipid layer, whose thickness is dependent upon the strength of the interfacial layer. (3) Using a tear film apparatus and interference patterns, we demonstrate the ability to produce a thickened lipid layer with a lipid-membrane-forming solution on individuals with meibomian gland dysfunction and resultant lipid layer deficiency. This membrane film can be maintained as part of the preocular tear film for up to 24 hours. Conclusions. An eye drop using interfacial molecule technology, allows for: (1) the production of a strong tear-film lipid-layer (that does not produce visual blur beyond seconds), and (2) products including: tear supplements, contact lens wetting and storage solutions, and drug delivery systems with a vastly enhanced pharmaceutical residence time and potency.

Determination of oxygen permeability/transmissibility and storage of contact lenses using HPLC with reductive electrochemical detection in combination with a specifically designed sampling unit.

A new analytical technique for the determination of oxygen permeability/transmissibility of contact lenses is presented in this paper. The method is based on high performance liquid chromatography (HPLC) with reductive electrochemical detection at -750 mV (vs Ag/AgCl) in combination with a patented sampling chamber that was designed especially for the purpose to determine oxygen at nanomolar levels. Compared to conventional method, the new technique exhibits higher sensitivity, selectivity, and versatility. The method permits the selective determination of oxygen permeability (Dk/L)/transmissibility (Dk) of soft as well as rigid contact lenses with good agreement with the Dk/L (Dk) values reported in the literature. Precision was determined by repeated measurements and yielded relative standard deviations of 3-8% for hydrophile lenses and 5-13% for rigid contact lenses. Because of the extraordinarily high sensitivity of the chromatographic oxygen sensor for the first time, the capability of hydrogel lenses to store oxygen could also be directly monitored.

Two different concentrations of Opti-Plus® compared for daily protein cleaning of a disposable contact lens

The aim of this study was to compare the relative safety, efficacy, comfort, and convenience of the daily use of a pancreatin-based, liquid enzyme daily protein remover (DPR) at two different concentrations for protein cleaning of Group IV disposable contact lenses. We enrolled 73 subjects (146 eyes) into a 3-month, randomized, investigator-masked clinical study comparing a test regimen of DPR (Opti-Plus® or Supra-Clens®) containing four drops per 10 mL of multifunctional solution (Opti-Free®) to a control regimen containing only two drops per 10 mL of multifunctional solution. The liquid enzyme regimens provided safe and effective protein cleaning of the Group IV lenses with no additional cleaning benefit observed at the higher concentration. Three convenience parameters (steps required, time required, and dexterity required) had mean improvements for both regimens at Day 90 compared to baseline (Day 0). Thus, subjects perceived the DPR regimen as more convenient than their pre-study regimen, which required weekly use of an enzymatic cleaning tablet. Comfort remained consistent with baseline levels throughout the study regardless of concentration of DPR for 72 of 73 subjects. This study provided evidence that the daily use of a low concentration pancreatin enzymatic solution admixed with multifunctional solution is well tolerated and provides a more convenient method of achieving simultaneous disinfection and protein cleaning during contact lens storage than enzyme tablets.

Epidemiology of Pseudomonas aeruginosa keratitis in contact lens wearers.

This study evaluated the epidemiology of Pseudomonas aeruginosa keratitis in contact lens (CL) wearers; the relationships between CL storage case contamination and CL hygiene practice and between CL hygiene and the development of keratitis. Sixteen CL wearers with keratitis were compared with 44 asymptomatic controls. Lens hygiene practice was assessed and CL care materials, domestic water sites and endogenous sites were evaluated microbiologically. Poor CL hygiene was not associated with Ps. aeruginosa keratitis. There was an association between keratitis and bacterial contamination of the CL and storage case (P < 0.0005). Lens and storage case contamination were not significantly associated with poor hygiene. No domestic or endogenous source for Ps. aeruginosa was found. Causative organisms may be derived from other sources, but CLs and CL storage cases provide a favourable environment for Ps. aeruginosa colonization. Changing the CL care environment to one less favourable for Ps. aeruginosa may help to eliminate this problem.

Laboratory investigation of Acanthamoeba keratitis

Following the diagnosis of Acanthamoeba keratitis in a contact lens wearer, the antimicrobial susceptibility of the clinical isolate and the environmental source of the infection were investigated. Contrary to previous reports, in vitro antimicrobial testing showed that the infecting strain was inherently resistant to propamidine isethionate. Restriction endonuclease digestion analysis of Acanthamoeba whole-cell DNA of strains isolated from the patient's cornea, contact lens storage container, saline rinsing solution, and kitchen cold-water tap showed that the isolates were identical. This implicates, for the first time, domestic tap water as the source of Acanthamoeba sp. in this infection. It is therefore recommended that the use of homemade saline solutions and the rinsing of contact lenses in tap water be strongly discouraged.

Contact Lens Storage, Wet or Dry?: A bacterial analysis

Contact Lens Storage, Wet or Dry?: A bacterial analysis