Contact Lens Disinfection Research Articles

Eumelanin-Enhanced Photothermal Disinfection of Contact Lenses Using a Sustainable Marine Nanoplatform Engineered with Electrospun Nanofibers.

Bacterial keratitis (BK) is a severe eye infection commonly associated with Staphylococcus aureus (S. aureus), posing a significant risk to vision, especially among contact lens wearers. This research introduces a novel smart nanoplatform (deMS@cNF), developed from demineralized mussel shells (deMS) and reinforced with chitin (CT) nanofibrils, specifically designed for portable photothermal disinfection of contact lenses. The nanoplatform leverages the photothermal properties of eumelanin in mussel shells (MS), which, when activated by a simple bike flashlight, rapidly heats to temperatures up to 95°C, effectively destroying bacterial contamination. In vitro tests demonstrate that the nanoplatform is biocompatible and non-toxic, making it suitable for medical applications. This study highlights an innovative approach to converting marine biowaste into a safe, effective, and low-cost portable method for disinfecting contact lenses, showcasing the potential of the deMS@cNF platform for broader antimicrobial applications.

Lactase can target cellular differentiation of Acanthamoeba castellanii belonging to the T4 genotype.

The free living Acanthamoeba spp. are ubiquitous amoebae associated with potentially blinding disease known as Acanthamoeba keratitis (AK) and a fatal central nervous system infection granulomatous amoebic encephalitis (GAE). With the inherent ability of cellular differentiation, it can phenotypically transform to a dormant cyst form from an active trophozoite form. Acanthamoeba cysts are highly resistant to therapeutic agents as well as contact lens cleaning solutions. One way to tackle drug resistance against Acanthamoeba is by inhibiting the formation of cysts from trophozoites. The biochemical analysis showed that the major component of Acanthamoeba cyst wall is composed of carbohydrate moieties such as galactose and glucose. The disaccharide of galactose and glucose is lactose. In this study, we analyzed the potential of lactase enzyme to target carbohydrate moieties of cyst walls. Amoebicidal assessment showed that lactase was ineffective against trophozoite of A. castellanii but enhanced amoebicidal effects of chlorhexidine. The lactase enzyme did not show any toxicity against normal human keratinocyte cells (HaCaT) at the tested range. Hence, lactase can be used for further assessment for development of potential therapeutic agents in the management of Acanthamoeba infection as well as formulation of effective contact lens disinfectants.

Cell death of Acanthamoeba castellanii following exposure to antimicrobial agents commonly included in contact lens disinfecting solutions.

Several antimicrobial agents are commonly included in contact lens disinfectant solutions including chlorhexidine diacetate (CHX), polyhexamethylene biguanide (PHMB) or myristamidopropyl dimethylamine (MAPD); however, their mode of action, i.e. necrosis versus apoptosis is incompletely understood. Here, we determined whether a mechanism of cell death resembling that of apoptosis was present in Acanthamoeba castellanii of the T4 genotype (NEFF) following exposure to the aforementioned antimicrobials using the anticoagulant annexin V that undergoes rapid high affinity binding to phosphatidylserine in the presence of calcium, making it a sensitive probe for phosphatidylserine exposure. The results revealed that under the conditions employed in this study, an apoptotic pathway of cell death in this organism at the tested conditions does not occur. Our findings suggest that necrosis is the likely mode of action; however, future mechanistic studies should be accomplished in additional experimental conditions to further comprehend the molecular mechanisms of cell death in Acanthamoeba.

Imidazolium ionic liquid as potential contact lens disinfectant inactivating cystic resistance forms from ACANTHAMOEBA keratitis

Keratitis caused by Acanthamoeba spp. is a rare disease, although increasingly common, especially among contact lens users. The occurrence and the devastating effect of this disease are associated with the lack of care in cleaning and disinfecting lenses and their storage cases, as well as ineffective drugs to mainly eliminate the parasite’s cysts. This work evaluated the amoebicidal activity of the imidazolium salt 1-hexadecyl-3-methylimidazolium chloride (C16MImCl) against cysts of two characterized isolates from Acanthamoeba keratitis cases (MZ404337 and MZ404332). The inactivation of 100% of the cysts was achieved at a concentration of 7.81 μg/mL for MZ404337 and of 1.95 μg/mL for MZ404332, both at 24 h and 48 h of exposure time. In contrast, a commercial formulation of chlorhexidine did not cause any reduction in the viability of the cysts. Related to the cytotoxicity to human HaCaT cells, C16MImCl is biocompatible at the concentration required to inactivate cysts. This shows that C16MImCl is a promising disinfectant for contact lenses and surfaces. KEY WORDS: 1-hexadecyl-3-methylimidazolium chloride; Acanthamoeba keratitis; cysts; chlorhexidine; cytotoxicity.

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.

Antiamoebic properties of Methyltrioctylammonium chloride based deep eutectic solvents.

This aim of this study was to assess anti-parasitic properties of deep eutectic solvents against eye pathogen, Acanthamoeba, often associated with the use of contact lens. Assays were performed to investigate the effects of various Methyltrioctylammonium chloride-based deep eutectic solvents on Acanthamoeba castellanii, comprising amoebicidal assays, encystment assays, excystment assays, cytotoxicity assays by measuring lactate dehydrogenase release from human cells, and cytopathogenicity assays to determine parasite-mediated host cell death. In a 2h incubation period, DES-B, DES-C, DES-D, and DES-E exhibited up to 85% amoebicidal activity at micromolar doses, which was enhanced further following 24h incubation. When tested in encystment assays, selected deep eutectic solvents abolished cyst formation and were able to block excystment of A. castellanii. All solvents exhibited minimal human cell cytotoxicity except DES-D. Finally, all tested deep eutectic solvents inhibited amoeba-mediated cytopathogenicity, except DES-B. Deep eutectic solvents show potent antiamoebic effects. These findings are promising and could lead to the development of novel contact lens disinfectants, as well as opening several avenues to explore the molecular mechanisms, various doses and incubation periods, and use of different bases against Acanthamoeba castellanii.

Efficacy of two contact lens disinfecting solutions in reducing growth rate of bacteria and eradication of biofilms

Efficacy of two types of contact lens disinfecting (CLD) solutions, most frequently purchased from Jordanian pharmacies by contact lens wearers, was investigated for reducing growth rate of methicillin resistant and methicillin sensitive Staphylococcus aureus, Serratia marcesence, S. liquefacience and Acinetobacter spp., previously isolated from In-use disinfecting solutions in CL cases. Each species was cultured in a clean and dirty conditions (to mimic real situation) of two fresh CLD solutions separately: A and B whose active agents are: Polyhexamethylene biguanide hydrochloride and Polyaminopropyl biguanide respectively. Log reduction of these bacteria have exceeded ISO 14729 acceptable criteria (3 log) and reached up to 5 log reduction. Dirty conditions have marked effect in reducing efficacy of CLD solution (A) to kill bacterial species under test. Biofilms produced by S. marcescens and S. liquefaciens were reduced by more than 50% after 24 hrs. using either CLD solutions, though it was less than that reduced after 4 hrs. Biofilm of methicillin resistant Staphylococcus aureus (MRSA) was the most affected by either CLD solutions after 4 hours. This study concluded that CL wearers should pay great consideration to cleaning and disinfection practices to decrease bacterial growth, reduce chances of biofilm formation.

Complete Recovery of Acanthamoeba Motility among Surviving Organisms after Contact Lens Care Disinfection

Acanthamoeba keratitis is a sight-threatening infection of the cornea which is extremely challenging to treat. Understanding this organism's responses during contact lens contact and disinfection could enhance our understanding of how Acanthamoebae colonize contact lens cases, better inform us on contact lens care solution (CLC) efficacy, and help us better understand the efficacy required of CLC products. To explore this gap in knowledge, we used Acanthamoeba ATCC 30461 and ATCC 50370 trophozoites to examine Acanthamoeba behavior during and after CLC disinfection. Amoebae were added to sterile aluminum flow cells and flow cell solutions were changed to Ringer's solution (control), or one of four CLCs based on biocides (PHMB, PAPB/Polyquad, Polyquad/Aldox, or Polyquad/Alexidine) for 6 h. Each flow cell solution was then changed to axenic culture media (AC6) for 12 h to determine the behavior of amoebae following disinfection. Distance, speed, and displacement were calculated for each organism. As compared to the control of one-quarter Ringer's solution, each CLC significantly impacted Acanthamoeba motility in both the CLC and AC6 conditions. However, the amoebae challenged with the PHMB CLC traveled a significantly greater total distance than with the other three CLCs, indicating differences in effectiveness between biocides. Furthermore, amoebae regaining motility post-disinfection by CLCs were observed to travel considerable distances and thus could be considered dangerous to ocular health. We determined that while all CLCs produced a substantial or complete cessation of movement vs. the control condition during disinfection, those which relied on the Polyquad biocides were the most effective, and that any amoebae which survived disinfection were able to recover motility. Future examinations of these findings should include direct correlations between motility and viability, and how infectivity and motility may be related.

Semiautomated disinfection of ophthalmic contact lenses.

The ophthalmic lenses that come in contact with the eyes pose a high risk for the transmission of bacterial and viral infections in eye clinics. Disinfecting these lenses does not happen stringently in a busy practice. We describe a novel method of disinfecting ophthalmic contact lenses using a semiautomated lens disinfector equipment, semiautomated lens disinfector. The equipment has motors to pump in and pump out water and disinfecting solution into a reservoir bath. The used ophthalmic lenses will be placed in a tray that partially dips into the bath for disinfection. Microbiology tests that were done to check the quality of the disinfection cycle showed good outcomes. Disinfection of ophthalmic contact lenses with the new equipment appeared to effectively eliminate contaminant microorganisms. This equipment can be used in busy ophthalmic clinics to alleviate the chances of cross-infection.

Effectiveness of Commonly Used Contact Lens Disinfectants Against SARS-CoV-2.

Objective:To assess the effect of commonly used contact lens disinfectants against severe acute respiratory syndrome corona virus 2 (SARS-CoV-2).Methods:The efficacy of five disinfectant solutions against SARS-CoV-2 was tested in the presence and absence of contact lenses (CLs). Three types of unused CLs (hard gas permeable, soft hydrogel, and soft silicone hydrogel) and worn silicone hydrogel CLs were tested. Contact lenses were infected with SARS-CoV-2 and disinfected at various times, with and without rubbing and rinsing, as per manufacturer's instructions. Reverse-transcriptase polymerase chain reaction (RT-PCR) and viability polymerase chain reaction (PCR) were applied to detect SARS-CoV-2 RNA and viral infectivity of SARS-CoV-2, respectively.Results:In the presence of SARS-CoV-2–infected CLs, no SARS-CoV-2 RNA could be detected when disinfectant solutions were used according to the manufacturer's instructions. When SARS-Co-V2–infected CLs were disinfected without the rub-and-rinse step, SARS-CoV-2 RNA was detected at almost each time interval with each disinfecting solution tested for both new and worn CLs. In the absence of CLs, viable SARS-CoV-2 was detected with all disinfectant solutions except Menicon Progent at all time points.Conclusions:Disinfectant solutions effectively disinfect CLs from SARS-CoV-2 if manufacturer's instructions are followed. The rub-and-rinse regimen is mainly responsible for disinfection. The viability PCR may be useful to indicate potential infectiousness.

T- and T′-type layered perovskite Ln2CuO4 nanocrystals for enhanced sensing detection of hydrogen peroxide

Nanostructured rare earth cuprates have recently attracted extensive attention as a promising non-noble metal electrocatalyst. However, they are rarely used to construct electrochemical sensors, even no report on hydrogen peroxide detection. Accordingly, two types of layered perovskite Ln2CuO4 nanocrystals with different structures, i.e., T-La2CuO4 and T′-Sm2CuO4 were synthesized from sol-gel method followed by calcining at 600 ℃ in air. Then, these nanomaterials were separately modified on the surface of bare glassy carbon electrode (GCE) by drop coating method, thus assembling efficient non-enzymatic H2O2 electrochemical sensor for the first time. In phosphate buffer solution (pH = 7.0), the La2CuO4/GCE shows high sensitivity (419.6 μA mM−1 cm−2) and low detection limit (160 nM) towards H2O2, which are significantly superior to those of Sm2CuO4/GCE. The difference in electrochemical sensing performance is mainly related to their electrode surface area and conductivity, characteristics of T- and T′-type layered structures, as well as the synergism of interstitial oxygen content and Cu2+/Cu+ redox coupling. In addition, La2CuO4/GCE has satisfactory selectivity and stability, and achieves the detection of trace H2O2 in rat serum, contact lens cleaning solution, tap water and disinfectant, indicating that it has certain practical applications in environmental protection and biological analysis.

A novel montmorillonite clay-cetylpyridinium chloride complex as a potential antiamoebic composite material in contact lenses disinfection

BackgroundAcanthamoeba keratitis is a painful, sight-threatening infection. It is commonly associated with the use of contact lens. Several lines of evidence suggest inadequate contact lens solutions especially against the cyst forms of pathogenic Acanthamoeba, indicating the need to develop effective disinfectants. ObjectiveIn this work, the application and assessment of montmorillonite clay (Mt-clay), cetylpyridinium chloride (CPC) and cetylpyridinium chloride-montmorillonite clay complex (CPC-Mt) against keratitis-causing A. castellanii belonging to the T4 genotype was studied. MethodsAdhesion to human cells and amoeba-mediated cytopathogenicity assays were conducted to determine the impact of Mt-clay, CPC and CPC-Mt complex on amoeba-mediated binding and host cell death. Furthermore, assays were also performed to determine inhibitory effects of Mt-clay, CPC and CPC-Mt complex on encystment and excystment. In addition, the cytotoxicity of Mt-clay, CPC and CPC-Mt complex against human cells was examined. ResultsThe results revealed that CPC and CPC-Mt complex presented significant antiamoebic effects against A. castellanii at microgram dose. Also, the CPC and CPC-Mt complex inhibited amoebae binding to host cells. Furthermore, CPC and CPC-Mt complex, were found to inhibit the encystment and excystment processes. Finally, CPC and CPC-Mt complex showed minimal host cell cytotoxicity. These results show that CPC and CPC-Mt complex exhibit potent anti-acanthamoebic properties. ConclusionGiven the ease of usage, safety, cost-effectiveness and long-term stability, CPC and CPC-Mt complex can prove to be an excellent choice in the rational development of contact-lens disinfectants to eradicate pathogenic Acanthamoeba effectively.

Antiamoebic properties of salicylic acid-based deep eutectic solvents for the development of contact lens disinfecting solutions against Acanthamoeba

Acanthamoeba castellanii is a protist pathogen that can cause sight-threatening keratitis and a fatal infection of the central nervous system, known as granulomatous amoebic encephalitis. In this study, effects of five malonic acid and salicylic acid-based deep eutectic solvents (DES) on A. castellanii were investigated. These are salicylic acid-trioctylphosphine (DES 1), salicylic acid- trihexylamine (DES 2), salicylic acid-trioctylamine (DES 3), malonic acid-trioctylphosphine (DES 4) and malonic acid-trihexylamine (DES 5). The experiments were done by performing amoebicidal, encystment, excystment, cytopathogenicity, and cytotoxicity assays. At micromolar dosage, the solvents DES 2 and DES 3 displayed significant amoebicidal effects (P < 0.05), inhibited encystment and excystment, undermined the cell-mediated cytopathogenicity of A. castellanii, and also displayed minimal cytotoxicity to human cells. Conversely, the chemical components of these solvents: salicylic acid, trihexylamine, and trioctylamine showed minimal effects when tested individually. These results are very promising and to the best of our knowledge, are reported for the first time on the effects of deep eutectic solvents on amoebae. These results can be applied in the development of new formulations of novel contact lens disinfectants against Acanthamoeba castellanii.

Antiviral Activity of Contemporary Contact Lens Care Solutions against Two Human Seasonal Coronavirus Strains.

Background: Given that reports have suggested SARS-CoV-2 can be transmitted via conjunctiva, the ability of contact lens (CL) care products to reduce the infectiousness of two seasonal human coronavirus (HCoV) (HCoV-229E and HCoV-OC43) surrogates for SARS-CoV-2 was investigated. Methods: Biotrue and Boston Simplus (Bausch&Lomb), OPTI-FREE Puremoist and Clear Care (Alcon), and cleadew and cleadew GP (Ophtecs) were tested. Their ability to inactivate HCoV was evaluated using contact times of 4 and 6 h as well as 1% and 10% of virus inoculum. Results: Non-oxidative systems (Biotrue, Boston Simplus, and OPTI-FREE) did not exhibit a significant log10 reduction compared to controls for the two viral strains for either incubation time (all p > 0.05) when 10% tests were performed. For the 1% test, while Boston Simplus and OPTI-FREE exhibited a significant log10 reduction of both HCoV-229E (after 6 h) and HCoV-OC43 (after either 4 or 6 h incubation), those products showed less than 1 log10 reduction of the two infectious viruses. Oxidative systems based on hydrogen peroxide or povidone-iodine showed a significant log10 reduction compared with the controls for both HCoV-229E and HCoV-OC43 in all tested conditions (all p < 0.01). Clear Care led to virus inactivation to below the limit of quantification for tests performed with 1% of inoculum after 6 h incubation, while cleadew and cleadew GP led to inactivation of the two viruses to below the limit of quantification in all tested conditions. Conclusion: Oxidative CL disinfection systems showed significant virucidal activity against HCoV-229E and HCoV-OC43, while non-oxidative systems showed minimal ability to inactivate the HCoV species examined.

Antibacterial effects of octadecyl trimethylammonium micelle-clay complex against bacterial eye pathogens: potential as a contact lens disinfectant.

In this study, we utilized a micelle-clay complex composed of the surfactant octadecyltrimethylammonium bromide and montmorillonite clay and evaluated its antibacterial effects. Using Pseudomonas aeruginosa, Staphylococcus epidermidis, and Micrococcus luteus, bactericidal assays were performed to determine the effects of ODTMA-clay complex on the viability of bacterial pathogen at various doses and different intervals of time. Cytotoxicity assays were performed to investigate ODTMA-clay complex effects on human cells, as determined by release of intracellular lactate dehydrogenase. The results revealed that ODTMA-clay complex abolished bacterial viability at 100μg/mL within 45min against P. aeruginosa, S. epidermidis, and M. luteus. Cytotoxicity assays revealed that ODTMA-clay complex exhibited minimal toxicity of the human cells. Rapid and potent antibacterial effects of ODTMA micelle-clay complex were observed in vitro; however, research is needed to determine precise formulation of contact lens disinfectants comprising ODTMA micelle-clay complex. Additionally, studies should be conducted using in vivo models of keratitis, progressing to pre-clinical and clinical trials. ODTMA micelle-clay complex is an ideal candidate to be incorporated in a novel contact lens disinfectant given the cost-effectiveness and ease of application and can be incorporated as an effective preventative strategy.

Cationic Surfactant-Natural Clay Complex as a Novel Agent Against Acanthamoeba castellanii Belonging to the T4 Genotype.

Acanthamoeba is a protozoan pathogen that is widely distributed in the environment. Given the opportunity, it can cause a serious eye infection known as Acanthamoeba keratitis as well as a fatal brain infection known as granulomatous amoebic encephalitis. Inappropriate use of contact lenses can contribute to contracting Acanthamoeba keratitis, and contact lens disinfectants are not always effective in eradicating Acanthamoeba. Therefore, there is a need to develop novel antimicrobial agents with efficient antiamoebic properties. In this study, we tested octadecyltrimethylammonium (ODTMA)-clay (montmorillonite) complex as a novel antiamoebic agent. Using A. castellanii belonging to the T4 genotype of keratitis origin, amobicidal assays were performed to determine the effects of ODTMA-cay complex on the viability of parasites at various concentrations ranging from 10 to 100 μg. Adhesion and cytopathogenicity assays were performed to investigate ODTMA effects on A. castellanii-mediated binding and damage to human cells. Encystation and excystation assays were conducted to establish ODTMA-mediated inhibitory effects against the cyst stage of A. castellanii. Using cell survival assays, the results revealed that ODTMA-clay complex exhibited amobicidal activity against keratitis-causing A. castellanii in a dose-dependent manner. Pretreatment of A. castellanii with ODTMA-clay complex inhibited parasite adhesion to as well as parasite-mediated human cell damage. Using encystation and excystation assays, it was revealed that ODTMA-clay complex inhibited A. castellanii cysts at 100 μg (P<0.05). To the best of our knowledge, for the first time, it was shown that ODTMA-clay complex exhibited anti-Acanthamoebic activities. The possibility of adding ODTMA-clay in a contact lens cleaning solution to formulate effective disinfectants is discussed further.

BCLA CLEAR - Contact lens wettability, cleaning, disinfection and interactions with tears

Contact lens materials have undergone significant changes over the past 20 years, particularly with respect to the introduction of silicone hydrogel materials. Whilst this development addressed hypoxic issues, other important areas relating to contact lens success, notably comfort, require further research.Contact lens wettability remains a crucially important part of biocompatibility. Contact lenses can be made more wettable by incorporation of surfactants into blister packs, internal wetting agents, surface treatments or care solutions. However, there remains no clear association between contact lens wettability and comfort, making it challenging to determine the potential for these approaches to be of significant clinical benefit. Most contact lenses are used on a daily wear, reusable basis, which requires them to be disinfected when not worn. The ideal disinfecting solution would also improve comfort during wear. However, balancing these requirements with other factors, including biocompatibility, remains a challenge. Soft lens materials invariably take up and subsequently release certain components of disinfecting solutions onto the ocular surface. This may affect tear film stability and the normal ocular microbiome, and further research is needed in this area to determine whether this has any affect on comfort. Finally, contact lens materials sorb components of the tear film, and these interactions are complex and may change the biochemistry of the tear film, which in turn may affect their comfort.In conclusion, the interaction between lens materials, tear film and disinfection solution plays an important role in the biocompatibility of lenses. However, the exact role and whether this can be altered to improve biocompatibility and comfort during wear remains debatable. This report summarises the best available evidence to examine this complex relationship and the opportunities for practitioners to enhance in-eye comfort of contemporary lenses, along with providing suggestions for areas of study that may provide further information on this topic.

Contact Lens Care: Past, Present and Future (a Literature Review)

Introduction. The number of contact lens users continues to increase, exceeding the total of more than 125 million people in the world. The trend of modern vision correction with contact lenses is the creation of customized contact lenses and specialty lens care products that better meet the needs of patients of all age groups.Purpose. To study the evolution of contact lens care products, their properties, composition characteristics, reliability of cleaning and disinfection, advantages and disadvantages of multifunctional solutions and peroxide systems, compatibility with contact lens materials as well as the effct of contact lens care solutions on the eye microbiome based on a literature data review.Material and methods. The analysis of scientifi publications available on Pubmed, BCLA, Elibrary, Elsevier and Medline for the last 20 years was carried out; 48 sources of literature were analyzed.Results. The analysis of literature has shown that the evolution of both contact lenses and contact lens care products has tightened the control over the safety of wearing. We have studied not only the composition and characteristics of each component of contact lens care and disinfection systems, but also the properties of the eye microbiome and its changes whilst wearing contact lenses. It is noted that under otherwise equal conditions, peroxide systems for contact lens care provide more reliable protection against contamination of all types of lenses, as well as ensure a better disinfection, protecting the eye from possible microbial, toxic and allergic complications. We also analyzed patients’ behavior and identifid their concerns during the COVID-19 pandemic.Conclusion. The patient’s choice of a lens care product must be approved by contact lens specialist and ophthalmologist. Contact lens care products should ensure perfect cleaning, maximum disinfection, hydration and be compatible with lens materials; they should be selected taking into account the patient-specifi characteristics of the ocular surface, lifestyle and health condition. It is necessary to continuously educate and inform patients about the importance of lens care products, and special attention should be paid to care during a pandemic for the safe wearing of CL.

Development of anti-acanthamoebic approaches

Acanthamoeba keratitis is a sight-endangering eye infection, and causative organism Acanthamoeba presents a significant concern to public health, given escalation of contact lens wearers. Contemporary therapy is burdensome, necessitating prompt diagnosis and aggressive treatment. None of the contact lens disinfectants (local and international) can eradicate Acanthamoeba effectively. Using a range of compounds targeting cellulose, ion channels, and biochemical pathways, we employed bioassay-guided testing to determine their anti-amoebic effects. The results indicated that acarbose, indaziflam, terbuthylazine, glimepiride, inositol, vildagliptin and repaglinide showed anti-amoebic effects. Compounds showed minimal toxicity on human cells. Therefore, effects of the evaluated compounds after conjugation with nanoparticles should certainly be the subject of future studies and will likely lead to promising leads for potential applications.

Effect of povidone iodine contact lens disinfecting solution on orthokeratology lens and lens case contamination and organisms in the microbiome of the conjunctiva

PurposeTo compare lens cleaning routines using a povidone iodine-based rigid lens disinfecting solution and its effect on conjunctival colonisation, and lens and lens case contamination. MethodsParticipants, aged 6–10 years, receiving orthokeratology treatment were randomised to four lens cleaning routines: with and without the use of daily and/or weekly cleaners, which were performed by their parents. Conjunctival colonisation was compared before lens wear and at 1-, 3-, and 6-month after commencement of lens wear. Contamination of lenses and lens cases was investigated at these times. Organisms were identified using MALDI-TOF mass spectrometry. ResultsOf the 76 participants who completed the study, conjunctival colonization was present in 24 (32 %) at baseline. Of the remaining 52 participants, 34 consistently yielded no growth. Participants positive at baseline were statistically more likely to be colonized after commencement of lens wear (p = 0.020). Overall, colonization rate was reduced to 15 % (11/72) after 6-month lens wear, which reached significance for initially colonized participants (p < 0.001). Few cultures yielded potential ocular pathogens, with notably no Pseudomonas aeruginosa. Contamination rates of both lenses and lens cases were also low, with few isolations of ocular pathogens. No significant differences were observed between cleaning regimes for conjunctival colonization or contamination of lenses or cases. ConclusionsDisinfection for rigid and ortho-k lens wearers may be effectively achieved with the use of povidone iodine-based solution, apparently regardless of cleaning routine adopted in the current study. The absence of pathogens in the conjunctiva, lenses, and lens cases in the great majority of samples indicates that it can improve the safety of overnight lens wear.