Contamination Of Contact Lenses Research Articles

Experimental Induction of Acute Acanthamoeba castellanii Keratitis in Cats.

To develop a feline model of acute Acanthamoeba keratitis using methods that replicate natural routes of infection transmission. Corneal Acanthamoeba castellanii inoculation was performed by three methods: topical inoculation with Acanthamoeba solution following corneal abrasion, placement of a contaminated contact lens for 7 days, and placement of a contaminated contact lens for 7 days following corneal abrasion. Sham inoculations with parasite-free medium and sterile contact lenses were also performed. Cats were monitored by ocular examination and in vivo corneal confocal microscopy for 21 days post-inoculation. Corneal samples were collected at intervals for microbiologic assessment, histopathology, and immunohistochemistry. All cats in the corneal abrasion groups developed clinical keratitis. Clinical ocular disease was inconsistently detected in cats from the contaminated contact lens only group. Initial corneal lesions were characterized by multifocal epithelial leukocyte infiltrates. Ocular lesions progressed to corneal epithelial ulceration and diffuse stromal inflammation. After 14 days, corneal ulcerations resolved, and stromal inflammation consolidated into multifocal subepithelial and stromal infiltrates. Corneal amoebae were detected by culture, in vivo confocal microscopy, histopathology, and immunohistochemistry in cats with keratitis. Neutrophilic and lymphocytic keratoconjunctivitis with lymphoplasmacytic anterior uveitis were identified by histopathology. Coinfection with aerobic bacteria was detected in some, but not all, cats with keratitis. Ocular disease was not detected in the sham inoculation groups. Feline Acanthamoeba keratitis is experimentally transmissible by contaminated contact lenses and topical inoculation following corneal epithelial trauma. Experimentally induced acute Acanthamoeba keratitis in cats is clinically and histopathologically similar to its human counterpart.

Hydrogen Peroxide-based Contact Lens Disinfection Systems Effective against SARS-CoV-2

While SARS-CoV-2 is a largely respiratory pathogen, it has been reported that the ocular surface may present a significant opportunity for infection either via airborne droplets or by self-contamination via touching an infected surface to the eye. In particular, contaminated contact lenses present a potential vector for microorganism transmission. It is then crucial to demonstrate that contact lens disinfection solutions are effective against the SARS-CoV-2 virus. Here, we applied the International Standards Organization protocol 14729 to assess the antiviral activity of CLEAR CARE® and CLEAR CARE® PLUS, hydrogen peroxide-based contact lens disinfection systems for use with soft contact lenses. Test samples were inoculated with 5.75 log10 TCID50/mL of SARS-CoV-2 and sampled at time zero and then again after the stated disinfection time of 6 hours. Both CLEAR CARE® and CLEAR CARE® PLUS demonstrated a 4.75 log reduction of the SARS-CoV-2 virus after 6 hours. No viable virus was recovered following disinfection with CLEAR CARE® and CLEAR CARE® PLUS. This data indicates the hydrogen peroxide-based contact lens disinfection systems are extremely effective at eliminating SARS-CoV-2, and these systems may provide patients with an effective option for contact lens disinfection in the face of this pandemic.

Acanthamoeba spp. aggregate and encyst on contact lens material increasing resistance to disinfection.

Acanthamoeba keratitis is often caused when Acanthamoeba contaminate contact lenses and infect the cornea. Acanthamoeba is pervasive in the environment as a motile, foraging trophozoite or biocide-resistant and persistent cyst. As contact lens contamination is a potential first step in infection, we studied Acanthamoeba's behavior and interactions on different contact lens materials. We hypothesized that contact lenses may induce aggregation, which is a precursor to encystment, and that aggregated encystment would be more difficult to disinfect than motile trophozoites. Six clinically and/or scientifically relevant strains of Acanthamoeba (ATCC 30010, ATCC 30461, ATCC 50370, ATCC 50702, ATCC 50703, and ATCC PRA-115) were investigated on seven different common silicone hydrogel contact lenses, and a no-lens control, for aggregation and encystment for 72 h. Cell count and size were used to determine aggregation, and fluorescent staining was used to understand encystment. RNA seq was performed to describe the genome of Acanthamoeba which was individually motile or aggregated on different lens materials. Disinfection efficacy using three common multi-purpose solutions was calculated to describe the potential disinfection resistance of trophozoites, individual cysts, or spheroids. Acanthamoeba trophozoites of all strains examined demonstrated significantly more aggregation on specific contact lens materials than others, or the no-lens control. Fluorescent staining demonstrated encystment in as little as 4 hours on contact lens materials, which is substantially faster than previously reported in natural or laboratory settings. Gene expression profiles corroborated encystment, with significantly differentially expressed pathways involving actin arrangement and membrane complexes. High disinfection resistance of cysts and spheroids with multi-purpose solutions was observed. Aggregation/encystment is a protective mechanism which may enable Acanthamoeba to be more disinfection resistant than individual trophozoites. This study demonstrates that some contact lens materials promote Acanthamoeba aggregation and encystment, and Acanthamoeba spheroids obstruct multi-purpose solutions from disinfecting Acanthamoeba.

Microbial Contamination of Soft Contact Lenses Among Medical School Students in Southern Iraq.

Contamination of CLs and accessories risks potentially devastating microbial keratitis. We aimed to explore the rate of microbial contamination and predisposing factors among a group of asymptomatic young medical students. The study included 115 healthy female medical students with a mean age of 21.64 ± 2.02 years between January and November 2021. Information about CL use, wear and care was gathered. Each participant's CL and case were swabbed for microbiological identification. Univariable and multivariable analyses were conducted to look for associations with a range of factors. Overall, 91 participants (79.13%) had at least one contaminated sample (lens and/or case). The rates of contamination of CL and their cases were 66% and 76.5%, respectively. Higher contamination rates were caused by gram-negative bacteria (60% of the contaminated samples) with P. aeruginosa being the most common contaminant both for CL and cases, whereas S. epidermidis and S. aureus were the most common contaminants for the CL and cases, respectively, regarding gram-positive contamination. Multivariable analysis showed younger age as a significant predictor of pseudomonas contamination of the lenses and cases (OR: 12.302, 6.555 for CL & cases, respectively; P = 0.001 for both). Older age was a significant predictor of K. pneumoniae contamination (OR: 4.154, P = 0.007). Pseudomonas contamination of both lenses and cases was predicted by the type of solution used (OR: 10.8 and 13.5, P = 0.001 and 0.003 for bottled and distilled water vs commercially available solutions for CL; OR: 4.5 and 5.8, P = 0.045 and 0.004, respectively, for cases). Pseudomonas case contamination was associated with low frequency of solution change. Microbial contamination rate of soft CL and their cases is high among young medical students in comparison to previously reported rates and was predisposed by several poor hygienic practices and wearing regimens.

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.

Identification Of Acanthamoeba spp. In Used Contact Lens Solution

Contact lenses are the most popular devices used by many people around the world for vision correction, aesthetics, and therapeutic purposes. Poor contact lens hygiene can cause various complications. One of the concerns regarding the use of contact lenses is the presence of Acanthamoeba spp. Acanthamoeba spp. is a free-living amoeba that can be found in many places including untreated fresh water, treated fresh water and unconventional water sources. One of the complications caused by Acanthamoeba spp. is Acanthamoeba keratitis which is an eye infection that is often caused by the use of contact lenses and contaminated contact lens solutions. Objective. The purpose of this study is to determine the description of Acanthamoeba spp. found in contact lens solution and contact lens care of Universitas Sumatera Utara students. Method. This study used univariate analysis. Data were obtained from the results of contact lens solution examination and questionnaire interviews. Result. Most of the samples (98%) did not have Acanthamoeba spp. Some respondents (60.8%) had fairly clean contact lens care behaviour and the rest (39.2%) had very clean contact lens care behaviour. Conclusion. One sample was found positive with Acanthamoeba spp. The positive sample had Acanthamoeba spp. cyst. Contact lens care was generally done well.

Antimicrobial efficacy of novel ultraviolet-C device in reducing contamination of contact lenses

Antimicrobial efficacy of novel ultraviolet-C device in reducing contamination of contact lenses

MICROBIAL BIOBURDEN OF ORTHOKERATOLOGY AND HYDROGEL CONTACT LENSES AND STORAGE CASES USING A HYDROGEN-PEROXIDE DISINFECTING SYSTEM

Background and objective: The fitting of orthokeratology (ortho-k) and multifocal soft contact lenses (SCL) is becoming increasingly popular worldwide for reducing the rate of myopia progression. However, overnight wear use of lenses and microbial contamination of contact lenses and storage vials has been shown to increase the risk of corneal inflammatory and infiltrative events (CIEs). Therefore, we conducted a pilot study to compare the rate, level, and type of microbial contamination of contact lenses and storage vialswhen participants wear ortho-k and SCL in combination with a hydrogen-peroxide disinfecting system.&#x0D; Material and Methods: A prospective, single-centre, randomized, crossover study was conducted to evalu-ate the rate and level of contact lens and storage vials contamination during the use of ortho-k and SCL along with a hydrogen-peroxide disinfecting solution over two 10 day wearing periods. Ocular signs and symptoms were assessed during lens wear at baseline and after each wearing period. In addition, contact lens and storage vials were collected, and the type and amount of microbial contamination were evaluated using viable culture and standard identification methods.Results: Twenty-five adults were enrolled, and 21 completed the study. One (5%) ortho-k lens, five (24%) ortho-k storage vials, one (5%) SCL and one (5%) SCL storage vial were contaminated (P &gt; 0.05), predominantly with Gram-positive bacteria. None of the participants had contamination with both ortho-k and SCL. No significant differences were found between the ocular signs, including conjunctival redness and roughness, or conjunctival or corneal staining (all P &gt; 0.05), irrespective of using ortho-k or SCL.&#x0D; Conclusion: This study provides the first data that directly compares microbial contamination of ortho-K versus SCL in patients using a hydrogen-peroxide disinfection system. However, the overall microbial contamination rate of contact lens storage vials was much lower (30%) than the previously reported study with ortho-k lens wear. The results support conducting a larger clinical trial designed to understand differences in microbial contamination with different lens materials and modalities.

Inactivation of Acanthamoeba Cysts in Suspension and on Contaminated Contact Lenses Using Non-Thermal Plasma.

Water suspensions of cysts of a pathogenic clinical isolate of Acanthamoeba sp. were prepared, and the cysts were inactivated either in suspension or placed on the surface of contact lenses by the non-thermal plasma produced by the DC corona transient spark discharge. The efficacy of this treatment was determined by cultivation and the presence of vegetative trophozoites indicating non-inactivated cysts. The negative discharge appeared to be more effective than the positive one. The complete inactivation occurred in water suspension after 40 min and on contaminated lenses after 50 min of plasma exposure. The properties of lenses seem to not be affected by plasma exposure; that is, their optical power, diameter, curvature, water content and infrared and Raman spectra remain unchanged.

Potential Transmission of Acanthamoeba spp. from Contact Lens Solution and Tap Water in Jakarta, Indonesia

BACKGROUND: Acanthamoeba spp. can cause corneal infection or keratitis that can be transmitted through contamination of contact lenses and water.&#x0D; AIM: The objective of this study was to determine the risk factors, transmission potential of Acanthamoeba spp. from the contact lenses cleaning solutions including the household water sources to the contact lens wearers.&#x0D; METHODS: The study was conducted between January 2019 and May 2019. An examination of Acanthamoeba was carried out by collecting contact lenses from 53 graduate students in a college in Jakarta. Their cleaning solutions of contact lenses and household water were also obtained. Each sample was separately examined for Acanthamoeba spp. in the Parasitology Laboratory of the Faculty of Medicine, Universitas Indonesia, on page – salt agar culture.&#x0D; RESULTS: The findings show 2 and 3 contact lens samples positive for Acanthamoeba spp. and other free-living ameba (FLA), respectively. In addition, from the cleaning solution and tap water samples revealed, there are 5 (9.4%) and 34 (64.1%) cultures positive for Acanthamoeba spp. and other FLA, respectively.&#x0D; CONCLUSION: A positive sample of Acanthamoeba spp. originating from the same source of the contact lens and tap water, indicating an association of Acanthamoeba spp. from contact lenses and tap water with the cleaning solutions of the contact lenses. Thus, there is might be a risk of transmission of Acanthamoeba sp. from household water to the cleaning solutions of contact lenses.

Ex vivo Cytopathic Effect Study of Human Acanthamoeba keratitis and Use of E. coli in Parasitic Culture

Acanthamoeba is free living amoeba and can cause Acanthamoeba keratitis, a serious disease which affects the cornea. It is widely existing in fresh water and soil. Acanthamoeba has three phases during the life cycle; trophozoite and a resistant double walled cyst and protocysts. The pathogenesis starts when the trophozoites bind to the surface of cornea by expressing mannose-binding protein which can bind to mannose glycoproteins on the corneal surface. The contaminated contact lenses can increase the infection by increasing the binding ability of the trophozoites. This project aimed to study the cytopathic effect of different stages Acanthamoeba keratitis. Study strains of Acanthamoeba castellani (ATCC 50370) was cultured and seeded in Hep2 cell lines. E. coli (strain M12) was used to isolate the trophozoites. The third stage, protocysts was made using Neff's medium. The cytopathic effect was checked trophozoites invasion to monolayer cells cultured in a small flask and in 24 well tissue culture plate. The time of destroying Hep2 cells by the trophozoites is less than that of other Acanthamoeba stages. The double ring-shaped cell wall of the cysts may increase the time-kill of Hep2 due to their resistant which was very slow to hatch. Reactivating the trophozoites from cysts then seeding in Hep2 destroyed the cells at less time compared fresh trophozoites as the virulence of the reactivated trophozoites being higher. The result could suggest that the infection of corneas with reactivated trophozoites may be more complex. Finally, the study found that the number of the trophozoites can limit the cytopathic effect of Acanthamoeba.

Hand hygiene is linked to microbial keratitis and corneal inflammatory events.

Lack of or inadequate hand washing is a risk factor in the development of contact lens related microbial keratitis and corneal inflammatory events. In the public health domain there is compelling evidence that proper hand washing with soap can save lives. The purpose of this review is to draw attention to some of the public health literature in support of hand washing and how education can influence patients' hand hygiene behavior. Contact lens wearers are also guilty of poor hand washing behavior but there is scant evidence that education of hand washing procedures of lens wearers alters patient non-compliance. It is well known that pathogenic microbial contamination of contact lenses, lens cases, care solutions and anterior ocular components have been found with contact lens wear. However while the originating source may be hands or water, it is most likely both of these. Besides proper hand washing this paper will include mitigating strategies for avoiding microbial contamination.

Eyeshadow – Polymer interaction in soft contact lenses

Purpose: The use of cosmetics associated with soft contact lenses (CLs) made of hydrogels (Hs) and silicone-hydrogels (SHs) may cause side effects. For this purpose, the contamination of soft CLs by a purple eyeshadow was evaluated both in vitro and in vivo.

Melimine-Coated Antimicrobial Contact Lenses Reduce Microbial Keratitis in an Animal Model

To determine the ability of antimicrobial peptide melimine-coated contact lenses to reduce the incidence of microbial keratitis (MK) in a rabbit model of contact lens wear. In vitro antimicrobial activity of melimine-coated contact lenses was determined against Pseudomonas aeruginosa by viable count and a radiolabeled assay. The amount of lipopolysaccharide (LPS) associated with bacteria bound to melimine-coated and control lenses was determined. Ocular swabs from rabbit eyes were collected for assessment of ocular microflora. A rabbit model for MK was developed that used overnight wear of contact lenses colonized by P. aeruginosa in the absence of a corneal scratch. During lens wear, detailed ocular examinations were performed, and the incidence of MK was investigated. Bacteria associated with worn lenses and infected corneas were determined by viable plate count. Inhibition in viable and total P. aeruginosa adhesion by melimine-coated contact lenses was 3.1 log10 and 0.4 log10, respectively. After colonization, the amount of LPS on lenses was approximately the same with or without melimine. Gram-positive bacteria were found in all the ocular swabs followed by fungus (42%). Melimine-coated lens wear was protective and significantly (odds ratio 10.12; P = 0.012) reduced the incidence of P. aeruginosa-driven MK in the rabbit model. The antimicrobial lenses were associated with significantly (P < 0.001) lower ocular scores, indicating improved ocular signs compared with controls. This study showed that contaminated contact lenses can produce MK without corneal epithelial defect in an animal model. Melimine-coated contact lenses reduced the incidence of MK associated with P. aeruginosa in vivo. Development of MK requires viable bacteria adherent to contact lenses, and bacterial debris adherent at the lens surface did not cause keratitis.

Microbial Contamination of Periorbital Tissues and Accessories of Children

To investigate normal flora of children with and without orthokeratology (ortho-k) treatment, and the associations between carriage of Staphylococcus aureus and Gram-negative rods with contamination of contact lenses and lens cases in ortho-k subjects and with spectacles of control subjects. Twenty-three ortho-k subjects (treatment >12 months) and 20 control myopic subjects aged 7-14 years were recruited. Samples were collected from four sites surrounding the left eye (lower conjunctiva, upper and lower eyelids, and eyelashes) for all subjects, spectacles for control subjects and contact lens accessories for ortho-k subjects. Samples were cultured, total numbers enumerated, and isolates identified using chromogenic agars. Ortho-k subjects had significantly less total isolates in the conjunctiva than controls (p = 0.009). Otherwise, carriage rates in normal flora levels of the peri-orbital tissues were not significantly different between the two groups (p > 0.19). The total isolates and carriage rates of normal flora on spectacles, contact lenses, and lens cases were similar to those identified on the skin tissues. Small numbers of bacteria were identified from the multipurpose solution of two ortho-k subjects. Although the association between the carriage of S. aureus with contamination of accessories was statistically significant only in control subjects (p = 0.03), ortho-k subjects not yielding S. aureus and Gram-negative rods from samples of their peri-orbital tissues tended to be less likely to have these organisms in their accessories. No Pseudomonas was isolated from any of the sites sampled and no Acinetobacter was isolated from any of the accessories. Ortho-k may lower the total number of bacteria in conjunctiva due to the use of solution and lenses, but the physiologic effect of this treatment on the types of normal flora in children was minimal and should not increase the risk of microbial keratitis in children with good compliance.

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study.

Background:Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear.Materials and Methods:Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A – dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing.Results:In Group A – 15 out of thirty samples were contaminated, in Group B – all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus.Conclusion:Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.

Contact lens hygiene compliance and lens case contamination: A review.

A contaminated contact lens case can act as a reservoir for microorganisms that could potentially compromise contact lens wear and lead to sight threatening adverse events. The rate, level and profile of microbial contamination in lens cases, compliance and other risk factors associated with lens case contamination, and the challenges currently faced in this field are discussed. The rate of lens case contamination is commonly over 50%. Coagulase-negative Staphylococcus, Bacillus spp., Pseudomonas aeruginosa and Serratia marcescens are frequently recovered from lens cases. In addition, we provide suggestions regarding how to clean contact lens cases and improve lens wearers' compliance as well as future lens case design for reducing lens case contamination. This review highlights the challenges in reducing the level of microbial contamination which require an industry wide approach.

Microbiologic Examination of Bandage Contact Lenses Used after Corneal Collagen Cross-linking Treatment

Purpose: To investigate the agents of bacterial contamination of contact lenses after corneal collagen cross-linking (CCL), and to present the possible changes of ocular flora after riboflavin/ultraviolet A.Methods: Seventy-two contact lenses of patients who underwent CCL and 41 contact lenses of patients who underwent photorefractive keratectomy (PRK) as control group were enrolled to the study. After 48 h of incubation, broth culture media was transferred to plates. Samples were accepted as positive if one or more colony-forming units were shown.Results: There were positive cultures in 12 (16.7%) contact lenses in the CCL group and 5 (12.2%) had positive cultures in PRK group. Coagulase-negative staphlycocci (CNS) were the most frequent microorganism. Alpha hemolytic streptococci and Diphteroid spp. were the other isolated microorganisms.Conclusions: Bacterial colonization can occur during and early after the CCL procedure in epithelial healing. To prevent corneal infections after the treatment, prophylactic antibiotics should be prescribed.

Corneal Inflammatory Events with Daily Silicone Hydrogel Lens Wear

This study aimed to determine the probability and risk factors for developing a corneal inflammatory event (CIE) during daily wear of lotrafilcon A silicone hydrogel contact lenses. Eligible participants (n = 218) were fit with lotrafilcon A lenses for daily wear and followed up for 12 months. Participants were randomized to either a polyhexamethylene biguanide-preserved multipurpose solution or a one-step peroxide disinfection system. The main exposures of interest were bacterial contamination of lenses, cases, lid margins, and ocular surface. Kaplan-Meier (KM) plots were used to estimate the cumulative unadjusted probability of remaining free from a CIE, and multivariate Cox proportional hazards regression was used to model the hazard of experiencing a CIE. The KM unadjusted cumulative probability of remaining free from a CIE for both lens care groups combined was 92.3% (95% confidence interval [CI], 88.1 to 96.5%). There was one participant with microbial keratitis, five participants with asymptomatic infiltrates, and seven participants with contact lens peripheral ulcers, providing KM survival estimates of 92.8% (95% CI, 88.6 to 96.9%) and 98.1% (95% CI, 95.8 to 100.0%) for remaining free from noninfectious and symptomatic CIEs, respectively. The presence of substantial (>100 colony-forming units) coagulase-negative staphylococci bioburden on lid margins was associated with about a five-fold increased risk for the development of a CIE (p = 0.04). The probability of experiencing a CIE during daily wear of lotrafilcon A contact lenses is low, and symptomatic CIEs are rare. Patient factors, such as high levels of bacterial bioburden on lid margins, contribute to the development of noninfectious CIEs during daily wear of silicone hydrogel lenses.

The efficacy of different commercial contact lens solutions on different concentrations of Acanthamoeba spp. trophozoites and cysts in Egypt

BackgroundAcanthamoeba spp. keratitis is a devastating disease that can potentially result in threatening the sight of the affected eye. Ineffective lens-disinfecting systems and contaminated contact lens storage cases have been recognized as the main risk factors for the infection.ObjectivesThe present study aimed to evaluate the efficacy of nine different commercially available contact lens solutions in the Egyptian market against Acanthamoeba spp. trophozoites and 2-week-old cysts.Materials and methodsNine solutions were tested: eight multipurpose solutions (MPS) and one one-step hydrogen peroxide solution. Acanthamoeba spp. was isolated from a keratitic patient, cultivated on 1.5% non-nutrient agar (NNA), harvested, adjusted in two final concentrations of 5 × 10 3 and 5 × 10 5 trophozoites and cysts, and then incubated with the contact lens solution. The efficacy was tested at intervals of 2, 4, 6, 8, 10, and 24 h. Experiments were performed in triplicate. The viability was confirmed by reinoculation onto NNA seeded with Escherichia coli (NNA-E. coli).ResultsMost of the tested solutions showed significant trophzoiticidal activity, whereas all of the tested solutions failed to eliminate the 2-week-old cysts completely. The one-step hydrogen peroxide system failed neutralization within the minimum manufacturer's disinfecting time as it killed all the cysts of 5 × 10 3 concentration after 10 h of soaking instead of 6 h; if used for this prolonged time, it could be hazardous to the users' eye. One of the MPS had high trophozoiticidal activity, but with an unknown recorded disinfectant, which could turn out to be of a toxic concentration or constitution.ConclusionAdjustment of the appropriate concentration of the disinfectant, the adequate exposure time, or even the development of new contact lens-disinfecting systems by manufacturers is needed to prevent Acanthamoeba spp. keratitis (AK). A MPS that fails to eradicate trophozoites or cysts within the minimum manufacturer's disinfecting time or one with an unknown recorded disinfectant should be avoided.