Microbial contamination of contact lenses, lens care solutions, and their accessories: a literature review

Process optimization and extraction of alkaline protease from halotolerant Streptomyces sp. VITGS3 and its use as a contact lens cleaner

Marine halotolerant actinobacteria are robust microbes poorly explored and barely cultivable in nature. They are a trove of various secondary metabolites and enzymes, especially the alkaline proteases withstanding higher temperatures, pH, and salinity, making them an ideal source with versatile commercial and therapeutic values. This study focuses on extracting and optimizing alkaline protease production from Streptomyces sp. VITGS3 isolated from Puthuvypeen, Kerala. The protease production was optimized by Response Surface Methodology (RSM) using the Box-Behnken model, which used rice bran, wheat bran, skim milk, and casein as substrates. The maximum protease was produced (357 U/mL) using wheat bran (5.5 % w/v) as substrate at pH 9 and incubated at 45 °C for 9 days. The Michaelis-Menten model's enzyme kinetics exhibited a Km value of 1.42 µM, a Vmax of 201.64 µM·min-1, V0 of 5.59 µM·min-1, and Kcat 70013.89 min-1 suggesting a higher affinity of the enzyme for the substrate (1 % w/v casein). In addition, the protease was inhibited by the phenylmethylsulphonyl fluoride (PMSF), suggesting it belongs to the serine protease family. Finally, the application studies as contact lens cleaners showcased that the isolated protease effectively degraded the protein deposits present in the artificial tear solution without affecting the light transmittance. This is a milestone in the implication of protease on therapeutic applications and further studies on protein specificity, sustained releases, and combination strategies, resulting in crucial challenges in long-term studies, cross-reactivity, storage, and cost-effectiveness.

Microbial contamination of therapeutic contact lenses after photorefractive keratectomy: a prospective analysis

PURPOSE

The objective of this study was to examine bacterial contamination in therapeutic contact lenses (TCLs) utilized following photorefractive keratectomy (PRK) and to identify factors correlated to positive culture outcomes.

METHODS

This prospective study comprised 120 eyes from 60 patients who underwent bilateral PRK surgery at Farabi Eye Hospital in 2022. TCLs, applied postoperatively, were collected between the fifth and seventh days, placed in sterile containers with culture media, and analyzed for microbial growth. The documentation included patient demographic information, refractive status, preoperative conditions, culture results, and antibiotic susceptibility data.

RESULTS

The results indicated microbial growth was detected in seven lenses, which accounts for 5.8% of the total number of lenses (120 TCLs). Coagulase-negative staphylococci (CoNS) (4 lenses, 2 methicillin-resistant staphylococci (MRS)), Escherichia coli (E. coli) (1 lens), diphtheroid (1 lens), and micrococcus species (1 lens) were the isolated organisms. The patients did not experience any instances of microbial keratitis during the study period. Patients with positive cultures demonstrated a significantly higher mean age (35.00 ± 7.09 years, P-value = 0.036). No significant gender disparities were identified (P-value = 0.263).

CONCLUSION

The incidence of microbial contamination in postoperative TCLs following PRK was minimal, with no occurrence of microbial keratitis. Older ages correlated with positive culture outcomes, highlighting the necessity for customized postoperative care approaches.

Parasitological and microbiological assessment of contact lens storage cases: a survey of asymptomatic lens student wearers from five medical specialties in Tunisia, North Africa

BACKGROUND

Contamination of contact lenses has always been correlated with contamination of lenses and lens storage cases (LSCs), with higher loads of microorganisms in LSCs. The aim of the present study is to better understand non-compliance with strict hygiene rules in asymptomatic contact lens wearers, and to track circulating germs in LSCs that may affect the integrity of the eye.

METHODS

Demographic and behavioral data were collected from 111 asymptomatic lens wearers belonging to different medical faculties in Tunisia. Seventy LSCs were subjected to microbiological investigations, by direct examination and culture, in order to identify contaminating micro-organisms. The Richness and evenness of the species encountered were assessed to measure biodiversity on a local and international scale.

RESULTS

The study population was characterized by an average age of 22.8 ± 2.4 years and 95% female gender. Microbiological contamination accounted for 81.42% of LSCs, with only one case positive for Acanthamoeba spp. The Candida spp. fungal elements (20.0%) and Staphylococcus coagulase negative bacteria (60.5%) were the predominant microorganisms. Biodiversity markers namely: Simpson (0.802) and Shannon-Weiner (1.895) diversity indices were high in comparison to other studies. Monthly lens renewal (OR = 1.333, p = 0.040) and soft lens wear (OR = 4.66, p = 0.066) enhanced the installation of fungal elements.

CONCLUSIONS

The behaviors of contact lens wearers observed in this work corroborate those of all studies of contact lens wearers. The complexity of the recommended procedure and poor understanding of the instructions may explain any imperfections. This study highlights a high level of biodiversity in LSCs, and the strains in circulation are almost potentially pathogenic for humans.

Proteases, a powerful biochemical tool in the service of medicine, clinical and pharmaceutical

Proteases, enzymes that hydrolyze peptide bonds, have various applications in medicine, clinical applications, and pharmaceutical development. They are used in cancer treatment, wound debridement, contact lens cleaning, prion degradation, biofilm removal, and fibrinolytic agents. Proteases are also crucial in cardiovascular disease treatment, emphasizing the need for safe, affordable, and effective fibrinolytic drugs. Proteolytic enzymes and protease biosensors are increasingly used in diagnostic and therapeutic applications. Advanced technologies, such as nanomaterials-based sensors, are being developed to enhance the sensitivity, specificity, and versatility of protease biosensors. These biosensors are becoming effective tools for disease detection due to their precision and rapidity. They can detect extracellular and intracellular proteases, as well as fluorescence-based methods for real-time and label-free detection of virus-related proteases. The active utilization of proteolytic enzymatic biosensors is expected to expand significantly in biomedical research, in-vitro model systems, and drug development. We focused on journal articles and books published in English between 1982 and 2024 for this study.

2024 American Heart Association and American Red Cross Guidelines for First Aid

Codeveloped by the American Heart Association and the American Red Cross, these guidelines represent the first comprehensive update of first aid treatment recommendations since 2010. Incorporating the results of structured evidence reviews from the International Liaison Committee on Resuscitation, these guidelines cover first aid treatment for critical and common medical, traumatic, environmental, and toxicological conditions. This update emphasizes the continuous evolution of evidence evaluation and the necessity of adapting educational strategies to local needs and diverse community demographics. Existing guidelines remain relevant unless specifically updated in this publication. Key topics that are new, are substantially revised, or have significant new literature include opioid overdose, bleeding control, open chest wounds, spinal motion restriction, hypothermia, frostbite, presyncope, anaphylaxis, snakebite, oxygen administration, and the use of pulse oximetry in first aid, with the inclusion of pediatric-specific guidance as warranted.

How Can We Better Inform Patients of the Importance of Contact Lens Compliance?: Current Perspectives

Compliance with contact lens care is important for successful contact lens wear and for minimizing the risk of complications related to lens wear. There are many components of overall lens care guidelines that may potentially be disregarded, forgotten, or misunderstood. Literature has reported copious data on rates of poor compliance for separate lens care recommendations. Knowing the areas of contact lens care where lens wearers perform poorly is helpful when creating strategies for improving patient education. As science evolves and new best-practices are determined, eye care providers must be engaged in educating new lens wearers and reeducating existing wearers. It is vital to make wearers mindful of proper lens care and why proper lens care should be important to them. Various educational strategies can help practitioners to communicate with their patients more effectively. The purpose of this narrative review is to discuss studies of noncompliance with contact lens wear; consequences of these noncompliant behaviors; and studies of lens care education which were found with a literature search. The resulting discussion also includes strategies to improve compliance with patient contact lens wear.

Care practices of contact lens solutions and microbial contamination among wearers in Ghana

PURPOSE

This study sought to assess contact lens solutions care practices, and their microbial contamination among contact lens wearers in Ghana and to profile their antibiotic susceptibility pattern.

METHODS

The study employed a biphasic approach which involved a cross-sectional design that investigated participants' habits related to care for the solutions with a two-part questionnaire and a microbiological analysis of samples of contact lens care solutions of the participants for microbial contamination. A snowball sampling method provided access to 32 different contact lens wearers in four care facilities in Ghana. In most cases, the participants had no pre-existing familial relationship with each other or with the care facilities.

RESULTS

Out of 32 samples of contact lens solutions, 30 were tested for microbial contamination. A total of 23 (76.67 %) samples of contact lens solution were found to be contaminated with Enterobacter sp. (34.80 %), Pseudomonas sp. (21.70 %), Bacilli sp. (21.70 %), Klebsiella sp. (17.20 %), and Escherichia coli (4.60 %). The duration of solution storage in the open bottle and nonadherence to manufacturer instructions for solution storage showed a statistically significant association with microbial contamination (p ≤ 0.05).

CONCLUSION

Contact lens care solutions have been found to harbour multiple antibiotic-resistant bacteria that are potentially pathogenic to the corneal surface. The contamination is associated with some unhealthy solution-care practices among wearers.

Contact lenses as a potential vehicle of Candida transmission

PURPOSE

Contact lenses can be contaminated with various microorganisms, including pathogenic yeasts of the genus Candida, which are known for their ability to adhere to abiotic surfaces, including plastic materials used for various medical purposes. Microbial contamination of the lenses can lead to infection of the wearer's eyes. The purpose of this study was to simulate the contamination of contact lenses with C. albicans and C. parapsilosis, analyze the interaction of the microorganisms with the lens material, and optimize the protocol for PCR-based analysis of the microbial agents responsible for lens contamination.

METHODS

Hilafilcon lenses were exposed to C. albicans and C. parapsilosis cultures, washed, and examined for their ability to further spread the contamination. Scanning electron microscopy was used to analyze the attachment of yeast cells to the lenses. Infrared spectroscopy was used to examine the potential changes in the lens material due to Candida contamination. The protocol for DNA isolation from contaminated lenses was established to enable PCR analysis of microbes attached to the lenses.

RESULTS

Hilafilcon lenses contaminated with Candida were able to spread the contamination even after washing with saline or with a commercial cleaning solution. In the present experimental settings, the yeasts did not grow into the lenses but began to form biofilms on the surface. However, the ability of the lenses to retain water was altered. The PCR-based protocol could be used to help identify the type of contamination of contact lenses.

CONCLUSION

Once contaminated with Candida albicans or Candida parapsilosis, Hilafilcon contact lenses are difficult to clean. Yeasts began to form biofilms on lens surfaces.

Long-Term Prevalence of Fungal Keratitis at a Swiss Tertiary Eye Clinic

Fungal keratitis is a rare yet severe infection of the cornea. Fungal species distribution depends on the climate and socioeconomic status and can show regional variation. This retrospective single-center study was conducted at a tertiary eye care center and the collaborating Institute of Medical Microbiology in Switzerland. On investigating all fungal-positive corneal scrapings and contact lens assessments of patients with keratitis from January 2012 to December 2023, 206 patients were identified, of which 113 (54.9%) were female. The median age was 38 (IQR 29.8, [18-93]), and 154 (74.8%) applied contact lenses. The most commonly found pathogen was Candida spp., followed by Fusarium spp. Molds were 1.8 times more common than yeasts. Linear regression showed no significant increase or decrease in the infection rate over time (p = 0.5). In addition, 10 patients (4.9%) were found to have coinfections with Acanthamoeba, 11 (5.3%) with HSV-1, none with HSV-2, and 4 (1.9%) with VZV. This study provides a long-term overview of fungal-positive corneal scrapings and contact lens specimens of patients with fungal keratitis. Based on our results, coinfections with Acanthamoeba, HSV, and VZV are frequent, especially in patients wearing contact lenses. Thus, wearing contact lenses may facilitate coinfection in fungal keratitis.

Microbial Contamination in Contact Lenses, Lens Care Solutions, and Accessories Among Asymptomatic Soft Contact Lens Users

Objective This study aimed to evaluate microbial contamination of contact lenses (CL) and their accessories among asymptomatic lens users and identify behavioral risk factors that might exacerbate the said contamination. Methodology Ninety-five asymptomatic soft CL users were recruited. In total, 380 samples were collected from the inner surface of lenses, the base of lens cases, the tip of the multipurpose solution bottle, and the solution itself. All swabs with samples were inoculated onto Columbia 5% sheep blood agar, MacConkey agar, Pseudomonas agar with cetrimide, and Sabouraud dextrose agar. Blood agar, MacConkey agar, and Pseudomonas agar with cetrimide were incubated at 37 °C for 24-48 hours. Fungal growth was investigated on Sabouraud dextrose agar, incubated at 25 °C, and examined daily for three weeks. Microscopic examination, culture-based methods, and biochemical tests were used to identify isolated microorganisms. A self-administered questionnaire on compliance with care and hygiene procedures was completed by each participant. Results The overall microbial contamination of tested samples was 38.7%. The most frequently contaminated items were lens cases (59, 62.1%), followed by bottles (44, 46.3%) and lenses (35, 36.8%). Meanwhile, the lowest incidence of contamination was seen in lens multipurpose solutions (9, 9.5%). The predominant microorganisms recovered were Coagulase-negative Staphylococci (CoNS) (94, 64%) and Gram-positive rods (29, 19.7%). Other identified potential pathogens were Staphylococcus aureus (11, 7.5%), Pseudomonas aeruginosa (5, 3.4%), Escherichia coli (1, 0.7%), and Candida albicans (2, 1.4%). The questionnaire revealed that contact lens users aged 18 to 20 showed a lack of compliance with proper hygienic care for contact lens maintenance. Risk factors such as male gender, smoking, showering, or swimming while wearing CL were related to microbiological contamination in at least one of the samples (P > 0.05). Conclusions The highest degree of contamination with highly virulent pathogens was determined in lens cases owing to insufficient lens care practices among study participants. Noncompliance with the lens cleaning procedures can lead to microbial colonization of the lens and its accessories, prompting inflammatory events in the eyes in the future.

Investigation of eye flora in cats infected with Herpesvirus and Calicivirus

Background and Objectives

The ocular surface is perpetually exposed to the external environment, rendering it susceptible to microbial contamination. The ocular surface microbiota consists of non-pathogenic microorganisms that inhabit the conjunctiva and cornea. This study's objective was to extensively review the prevalence of bacterial and fungal organisms in the conjunctiva of healthy and diseased cats. (Herpes- and Calici-infected groups).

Materials and Methods

The current study was performed on 240 cats that had visited veterinary health centers (Tehran, Iran) for examination. Sterile swabs from each cat's eyes were investigated for microbiological assessment. After sample collection, viral pathogens (Herpes and Calici viruses) were isolated and identified using the PCR method. The ages of the investigated group were 3.76, 3.93, and 4.15 months.

Results

The highest frequency of bacteria in the normal, Herpes-infected/Calici-infected, and Herpes/Calici-infected groups were associated with Staphylococcus intermedius and Streptococcus agalactiae, Staphylococcus epidermidis, and Staphylococcus intermedius, respectively. In addition, it was found that the high prevalence of fungal microorganisms in the isolated samples was related to yeasts, Aspergillus (Aspergillus fumigatus, Aspergillus niger), and Penicillium species.

Conclusion

Bacterial prevalence was significantly higher in all groups than the prevalence of fungi in the eyes of cats. The statistical comparison between the study groups regarding microbial and fungal frequency showed that significant differences were found between them, such that the frequency was higher in all disease groups, against the control group. In addition, a significant relation was observed between the Herpes-infected and Calici-infected groups regarding microbial and fungal prevalence.

Association Between Serratia marcescens Contamination and Hygiene Compliance in Orthokeratology

BACKGROUND/AIM

Given the characteristics of Serratia marcescens (S. marcescens), this study aimed at investigating its presence in the hands and contact lens cases of orthokeratology wearers, along with the status of bacterial contamination.

PATIENTS AND METHODS

The 39 patients received the questionnaires about the background of orthokeratology and hygiene habits. A total of 39 contact lens cases and 39 hand samples from the patients were collected at Show Chwan Memorial Hospital from June to August in 2020 and sent to National Chung Cheng University for DNA extraction and PCR identification.

RESULTS

The results indicated a detection rate of 5.13% for S. marcescens in the contact lens cases and 12.82% in the hand samples. Additionally, 66.67% of contact lens case samples and 30.77% of hand samples found positive for 16s bacterial amplicons. The relationship between hand contamination and the duration of contact lens usage were revealed for both S. marcescens (p=0.021) and 16s bacterial amplicons (p=0.048).

CONCLUSION

The results indicated that hand hygiene is more critical than focusing on contact lens hygiene when it comes to preventing S. marcescens infections. Nevertheless, both proper hand and contact lens hygiene practices can reduce the detection of bacterial eye pathogens, especially a common intestinal bacterium.

Advances in Contact Lens Care Solutions: PVP-I Disinfectant and HAD Wetting Agents From Japan

ABSTRACT

Half of the individuals who wear contact lenses use reusable lenses that require proper care. Improper contact lens (CL) care and using inadequate disinfecting solutions can lead to lens contamination, CL-related microbial keratitis, and Acanthamoeba keratitis. Oxidative disinfecting solutions, such as hydrogen peroxide, show higher efficacy than multipurpose solutions. Povidone-iodine (PVP-I), an oxidative disinfectant used in ophthalmic surgery, has been proven to be safe and effective. The PVP-I system, a CL disinfecting solution developed in Japan, has demonstrated excellent antimicrobial and antiviral properties. Although CL discomfort does not have a risk of ocular disorders with poor visual prognosis, such as keratitis, CL discomfort can still lead to lens dropout and thus needs to be addressed. To mitigate CL discomfort, it is essential to use disinfecting solutions containing surfactants and wetting agents that improve wettability of the lens surface. A CL solution containing hyaluronic acid derivatives (HADs) as wetting agents that permanently adhere to the lens surface to improve wettability of the lens surface was developed in Japan. There is potential for HAD to be integrated into various solutions. This article reviews the efficacy of novel PVP-I-based disinfecting solution and HAD wetting agents.

A Comparison of Culture Results and Visual Acuity in Contact Lens Related Microbial Keratitis

PURPOSE

Evaluate the effect of corneal and contact lens-related (CLR) culture results on visual acuity (VA) in patients with microbial keratitis (MK).

METHODS

MK patients with corneal and CLR cultures were identified in the University of Michigan electronic health record from August 2012 to April 2022. Test results were classified as laboratory-positive or laboratory-negative. Linear regression was used to examine trends of VA and associations between changes in VA (differences of VA at 90-day and baseline VA) and corneal and CLR culture results, after adjustment for baseline VA. One-sample t-tests were used to test if the slope estimates were different from zero.

RESULTS

MK patients (n = 50) were on average 49 years old (standard deviation = 20.9), 56% female, and 90% White. Positive corneal and CLR cultures were reported in 60% and 64% of patients, respectively, and 38% reported both. The agreement rate between corneal and CLR culture results was 30% (n = 15/50). LogMAR VA improved over time in patients with positive corneal and CLR cultures (Estimate=-0.19 per 10-day increase, p = 0.002), and in those with negative corneal and positive CLR cultures (Estimate= -0.17 per 10-day increase, p = 0.004). Compared to patients with negative corneal and CLR cultures, there was a trend toward improvement in VA for patients with positive corneal and CLR cultures (Estimate=-0.68, p = 0.068), and those with negative corneal and positive CLR cultures (Estimate= -0.74, p = 0.059), after adjusting for baseline VA.

CONCLUSIONS

Positive CLR cultures are associated with significant improvement in VA over time. These additional cultures can provide guidance on appropriate antimicrobial selection, especially when corneal cultures are negative.

Alterations of conjunctival microbiota associated with orthokeratology lens wearing in myopic children

BACKGROUND

Orthokeratology (OK) lens wear increases the risk of bacterial infection, but little is known about the microbiota of the conjunctival sac in myopic children wearing OK lenses. This study aimed to investigate the changes of conjunctival microbiota in children after treatment with OK lenses using 16 S rDNA sequencing.

METHODS

Twenty-eight myopic children who had been continuously wearing OK lenses for 12 to 13 months were enrolled in this prospective study. Twenty-two gender- and age-matched myopic children who had not worn OK lenses or discontinued OK lens wear at least 1 year ago were recruited as controls. Conjunctival swabs from each participant were collected for exploration of the microbiota profiles, targeting the V3-V4 regions of the 16 S rRNA gene by MiSeq sequencing. The differences in the microbial community structure and diversity were also compared between groups.

RESULTS

The bacterial alpha diversity indices in the OK lens group were not different from those in the non-wearer group (P > 0.05, Wilcoxon test), while beta diversity examined using principle coordinate analysis of unweighted UniFrac divided the two groups into different clusters. Proteobacteria, Bacteroidetes, and Firmicutes were the abundant phyla in the conjunctival sac microbiota in both groups (P < 0.05, Mann-Whitney U test). Among children in the OK lens group, the Linear discriminant analysis Effect Size identified the compositional changes in OK lens-associated bacteria. Key functional genera such as Blautia, Parasutterella, and Muribaculum were enriched, whereas Brevundimonas, Acinetobacter, Proteus, and Agathobacter decreased significantly (P < 0.05, Mann-Whitney U test). Phylogenetic investigation of communities by reconstruction of unobserved states also showed altered bacterial metabolic pathways in OK lens-associated microbiota. Moreover, using receiver operating characteristic curves, Brevundimonas, Acinetobacter, Proteus, and Agathobacter alone (the area under the curve was all > 0.7500) or in combination (the area under the curve was 0.9058) were revealed to discriminate OK lens wearers from controls.

CONCLUSIONS

The relative abundance of the microbial community in the conjunctival sac of myopic children can alter after OK lens wear. Brevundimonas, Acinetobacter, Proteus, and Agathobacter may be candidate biomarkers to distinguish between OK lens wearers and non-wearers.

Microbiological Characteristics and Risk Factors Involved in Progression from Fungal Keratitis with Hypopyon to Keratitis-Related Endophthalmitis

PURPOSE

To investigate the differences in microbiological characteristics, risk factors, drug resistance, and visual outcomes in three infections: fungal keratitis with hypopyon (FKH), keratitis-related fungal endophthalmitis (FKE), and fungal endophthalmitis without keratitis (FE).

METHODS

An analytical cross-sectional study.

RESULTS

In total, 14.57% of eyes with FKH progressed to endophthalmitis. Hypopyon, pre-existence of lens problems, topical steroid use and sever keratitis were significantly associated with the development of FKE. The risk factors of the FKH and FE group were mainly plant trauma and open globe trauma, respectively. Keratitis-related endophthalmitis (FKE) showed a significantly higher resistance than the other two groups. The FKH group had the best final visual acuity, while the FKE group had the worst.

CONCLUSION

Hypopyon height, pre-existing lens problems, topical steroid use and sever keratitis are risk factors for progression to endophthalmitis in eyes with fungal keratitis, and its progression is not affected by a single fungus. The antifungal drugs resistance in patients with endophthalmitis related to keratitis was significantly higher than that associated with other reasons. Timely diagnosis and risk factor assessment are essential for ensuring early treatment of FKE.

TFOS Lifestyle: Impact of contact lenses on the ocular surface

Several lifestyle choices made by contact lens wearers can have adverse consequences on ocular health. These include being non-adherent to contact lens care, sleeping in lenses, ill-advised purchasing options, not seeing an eyecare professional for regular aftercare visits, wearing lenses when feeling unwell, wearing lenses too soon after various forms of ophthalmic surgery, and wearing lenses when engaged in risky behaviors (e.g., when using tobacco, alcohol or recreational drugs). Those with a pre-existing compromised ocular surface may find that contact lens wear exacerbates ocular disease morbidity. Conversely, contact lenses may have various therapeutic benefits. The coronavirus disease-2019 (COVID-19) pandemic impinged upon the lifestyle of contact lens wearers, introducing challenges such as mask-associated dry eye, contact lens discomfort with increased use of digital devices, inadvertent exposure to hand sanitizers, and reduced use of lenses. Wearing contact lenses in challenging environments, such as in the presence of dust and noxious chemicals, or where there is the possibility of ocular trauma (e.g., sport or working with tools) can be problematic, although in some instances lenses can be protective. Contact lenses can be worn for sport, theatre, at high altitude, driving at night, in the military and in space, and special considerations are required when prescribing in such situations to ensure successful outcomes. A systematic review and meta-analysis, incorporated within the review, identified that the influence of lifestyle factors on soft contact lens dropout remains poorly understood, and is an area in need of further research. Overall, this report investigated lifestyle-related choices made by clinicians and contact lens wearers and discovered that when appropriate lifestyle choices are made, contact lens wear can enhance the quality of life of wearers.

Candida Colonization on the Surface of Contact Lenses in Long-Term Wearers and Boston Type 1 Keratoprosthesis Patients Presenting as White Mulberry-Shaped Deposits

PURPOSE

To report Candida colonies on the surface of the contact lens in long-term contact lens wearers and patients with Boston type 1 keratoprosthesis (KPro I).

METHODS

A retrospective study was performed based on analyzing cultures from bandage contact lenses with small whitish mulberry-shaped deposits on their surface.

RESULTS

Eight samples (from seven patients) were positive for Candida. Seven of the eight were positive for Candida parapsilosis.

CONCLUSIONS

The whitish deposits on contact lenses are often Candida colonies that colonize the surface but do not cause an active infection in the eye. C. parapsilosis is well-known for colonizing prosthetic devices. We underline the importance of including Candida species in the differential diagnosis of lens deposits, especially in susceptible patients such as keratoprosthesis carriers.

Compliance of Soft Contact Lens Care and Bacterial Contamination Among University Students in Palestine

PURPOSE

This study investigated the contact lens care compliance, noncompliance reasons, bacterial contamination rate, and the behaviors associated with contamination among university students in Palestine.

PATIENTS AND METHODS

133 Habitual soft contact lens wearers were recruited in this study and interviewed using a face-to-face questionnaire, to obtain data on demographics, contact lenses, modifiable lens care behaviors and the reasons for non-compliance. High, moderate, and low lens care behaviors were identified. Additionally, a sample of the participant's storage cases was collected for bacterial contamination testing.

RESULTS

The participants' mean age was 22.4±4.4, with female predominance (62.4%). The average compliance rate was 76.8%. Total CL care compliance (100%) was found in filling the case with adequate solution, not sharing the lenses or storage case with others, while the poorest compliance (>40%) was found in attending after-care visits, checking the solution's expiry, and re-disinfecting the lenses with a fresh solution before insertion after prolonged storage. Poor understanding of the instructions contributed significantly to a low level of compliance (P≤0.05). Gram-positive and gram-negative bacteria were detected in 19.55% of the participants' cases. Poor hand and case hygiene, no replacement of lens cases (monthly), and water exposure were linked to bacterial contamination of storage cases.

CONCLUSION

This study indicated moderate to high compliance in CL care, averaging 76.8%. Poor compliance was found in attending after-care visits, checking the solution's expiry, and re-disinfecting the lenses with a fresh solution after an extended storage interval. 19.55% of the cases had bacterial contamination, with Staphylococcus Aureus being the most common. Poor hand and lens case hygiene and water exposure are found to be associated with lens case contamination. These findings emphasize the importance of patient education on safer lens wear modalities, proper wearing schedules, and hygiene regimens to reduce the risks of developing contact lens complications.

Viral Infection and Antiviral Treatments in Ocular Pathologies

Ocular viral infections are common and widespread globally. These infectious diseases are a major cause of acute red eyes and vision loss. The eye and its nearby tissues can be infected by several viral agents, causing infections with a short course and limited ocular implications or a long clinical progression and serious consequences for the function and structure of the ocular region. Several surveillance studies underline the increased emergence of drug resistance among pathogenic viral strains, limiting treatment options for these infections. Currently, in the event of resistant infections, topical or systemic corticosteroids are useful in the management of associated immune reactions in the eye, which contribute to ocular dysfunction. Many cases of viral eye infections are misdiagnosed as being of bacterial origin. In these cases, therapy begins late and is not targeted at the actual cause of the infection, often leading to severe ocular compromises, such as corneal infiltrates, conjunctival scarring, and reduced visual acuity. The present study aims at a better understanding of the viral pathogens that cause eye infections, along with the treatment options available.

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

Background

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.

Methodology

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.

Results

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.

Conclusion

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.

Biofilms: Formation, Research Models, Potential Targets, and Methods for Prevention and Treatment

Due to the continuous rise in biofilm-related infections, biofilms seriously threaten human health. The formation of biofilms makes conventional antibiotics ineffective and dampens immune clearance. Therefore, it is important to understand the mechanisms of biofilm formation and develop novel strategies to treat biofilms more effectively. This review article begins with an introduction to biofilm formation in various clinical scenarios and their corresponding therapy. Established biofilm models used in research are then summarized. The potential targets which may assist in the development of new strategies for combating biofilms are further discussed. The novel technologies developed recently for the prevention and treatment of biofilms including antimicrobial surface coatings, physical removal of biofilms, development of new antimicrobial molecules, and delivery of antimicrobial agents are subsequently presented. Finally, directions for future studies are pointed out.

A CASE OF TRAUMATIC SOFT CONTACT LENS DISLOCATION INTO THE VITREOUS SPACE AFTER CORNEAL PERFORATION IN A PHAKIC EYE: A NOVEL INDICATION FOR MEMBRANEBLUE-DUAL

PURPOSE

To describe a case of traumatic soft contact lens dislocation into the vitreous space after a large-sized corneal perforation with a clout nail, causing aniridia but leaving the crystalline lens intact.

METHODS

A case report of a 44-year-old male patient with a corneal perforation.

RESULTS

The patient presented with a traumatic corneal perforation after a large clout nail impacted on his left eye. Aniridia and inferior zonulolysis were seen, but the crystalline lens was perfectly clear. Because computed tomography imaging and B-scan ultrasonography showed no signs of intraocular foreign body, a vitrectomy was performed seven days after primary repair to allow for proper wound closure. During vitrectomy, a completely intact soft contact lens was found in the vitreous cavity. The soft contact lens was stained with MembraneBlue-Dual (D.O.R.C., the Netherlands) to enhance visualization and ensure complete removal by the vitreous cutter.

CONCLUSION

MembraneBlue-Dual can be used to facilitate complete removal of a clear and otherwise difficult to see corneal contact lens from the vitreous cavity. This case also demonstrates the importance of exploratory vitrectomy in all trauma cases with posterior segment involvement, even when imaging modalities show no signs of intraocular foreign bodies.

Antimicrobial Efficacy of an Ultraviolet-C Device against Microorganisms Related to Contact Lens Adverse Events

The purpose of the study was to assess the antimicrobial activity of an ultraviolet-C (UVC) device against microorganisms implicated in contact lens related adverse events. An UVC device with an emitting 4.5 mm diameter Light Emitting Diode (LED; 265 nm; 1.93 mJ/cm2) was used. Pseudomonas aeruginosa, Staphylococcus aureus, Fusarium solani, and Candida albicans agar plate lawns were exposed to the device beams for 15 and 30 s at 8 mm distance. Following the exposure, the diameter of the growth inhibition zone was recorded. Contact lenses made of Delfilicon-A, Senofilicon-A, Comfilicon-A, Balafilicon-A, Samfilicon-A and Omafilicon-A and a commercially available contact storage case was used. They were exposed to bacterial and fungal strains for 18 h at 37 °C and 25 °C respectively. After this, the samples were exposed to UVC for 30 s at 8 mm distance to determine the antimicrobial efficacy. Samples were then gently washed and plated on appropriate agar for enumeration of colonies. The UVC exposure reduced microbial growth by 100% in agar lawns, and significantly (p < 0.05) reduced microbial contamination to contact lenses and cases, ranging between 0.90 to 4.6 log. Very short UVC exposure has high antimicrobial efficacy against most of the predominant causative microorganisms implicated in contact lens related keratitis. UVC could be readily used as a broad-spectrum antimicrobial treatment for lens disinfection.

Poly(2-hydroxyethyl methacrylate-co-quaternary ammonium salt chitosan) hydrogel: A potential contact lens material with tear protein deposition resistance and antimicrobial activity

Tear protein deposition resistance and antimicrobial property are two challenges of conventional poly(2-hydroxyethyl methacrylate) (pHEMA) contact lenses. In this work, we developed a poly(2-hydroxyethyl methacrylate-co-quaternary ammonium salt chitosan) hydrogel, named as p(HEMA-co-mHACC) hydrogel, using acryloyl HACC (mHACC) as a macromolecular crosslinker. With increasing the acryloyl substitution degree (14-29%) or mHACC content (2-11%), the hydrogel showed an enhanced tensile strength (432-986 kPa) and Young's modulus (360-1158 kPa), a decreased elongation at break (242-84%), and an increased visible light transmittance (0-95%). At an optimal acryloyl substitution degree of 26%, with the increase of mHACC content from 2% to 11%, p(HEMA-co-mHACC) hydrogel presented a decreased water contact angle from 84.6 to 55.3 degree, an increased equilibrium water content from 38% to 45%, and an enhanced oxygen permeability from 8.5 to 13.5 barrer. Due to the enhancement in surface hydrophilicity and electropositivity, p(HEMA-co-mHACC) hydrogel remarkably reduced the deposition of lysozyme, but little affected the adsorption of BSA, depending on the hydrophilic/hydrophobic and electrostatic interactions. The antimicrobial test against Staphylococcus aureus and Escherichia coli showed that p(HEMA-co-mHACC) hydrogel presented an 8-32 times higher germicidal ability than pHEMA hydrogel, indicative of a better antimicrobial activity. The in vitro cell culture of mouse NIH3T3 fibroblasts and immortalized human keratinocytes showed that p(HEMA-co-mHACC) hydrogel was non-toxic. Thus, p(HEMA-co-mHACC) hydrogel with tear protein deposition resistance and antimicrobial activity is a potential candidate for contact lenses.

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

SIGNIFICANCE

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.

PURPOSE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Differential Antimicrobial Efficacy of Preservative-Free Contact Lens Disinfection Systems against Common Ocular Pathogens

Microbial keratitis is a devastating disease that can cause eye damage and blindness and can be the result of infections by several common ocular pathogens. Importantly, some of these pathogens, such as Acanthamoeba, are particularly unsusceptible to biocides in common contact lens care solutions. Therefore, the disinfection efficacy of preservative-free (PF) disinfection systems against bacteria, fungi, and Acanthamoeba trophozoites and cysts should be assessed as products with the most potential to be efficacious against resistant organisms. PF disinfection systems were analyzed for antimicrobial efficacy. These were the one-step (hydrogen peroxide-based) Clear Care and Clear Care Plus systems and the two-step (povidone-iodine-based) Cleadew system. Stand-alone challenges using bacteria, fungi, and Acanthamoeba were prepared according to the International Standards Organization method 14729. These same challenges were also conducted in the presence of the following contact lenses: Boston RGP, Acuvue Oasys, Biofinity, Ultra, and 2-week PremiO. All challenges were performed at the manufacturer's recommended disinfection time. All preservative-free disinfection systems demonstrated similarly high rates of antimicrobial efficacy when challenged with bacteria or fungi, with or without lenses. However, both Clear Care and Clear Care Plus demonstrated significantly greater disinfection efficacy against Acanthamoeba trophozoites and cysts, with and without lenses (P < 0.05). Cleadew efficacy was impacted by the addition of contact lenses, whereas Clear Care/Clear Care Plus maintained similar efficacies in the absence or presence of lenses. While both hydrogen peroxide and povidone-iodine are highly effective against bacteria and fungi, hydrogen peroxide maintains significantly greater disinfection capabilities than povidone-iodine against all forms of Acanthamoeba. IMPORTANCE Understanding the most efficacious products will allow clinicians to best communicate to patients and consumers the safest products on the market to reduce adverse events, including microbial keratitis, during contact lens use.

Ptychographic sensor for large-scale lensless microbial monitoring with high spatiotemporal resolution

Traditional microbial detection methods often rely on the overall property of microbial cultures and cannot resolve individual growth event at high spatiotemporal resolution. As a result, they require bacteria to grow to confluence and then interpret the results. Here, we demonstrate the application of an integrated ptychographic sensor for lensless cytometric analysis of microbial cultures over a large scale and with high spatiotemporal resolution. The reported device can be placed within a regular incubator or used as a standalone incubating unit for long-term microbial monitoring. For longitudinal study where massive data are acquired at sequential time points, we report a new temporal-similarity constraint to increase the temporal resolution of ptychographic reconstruction by 7-fold. With this strategy, the reported device achieves a centimeter-scale field of view, a half-pitch spatial resolution of 488 nm, and a temporal resolution of 15-s intervals. For the first time, we report the direct observation of bacterial growth in a 15-s interval by tracking the phase wraps of the recovered images, with high phase sensitivity like that in interferometric measurements. We also characterize cell growth via longitudinal dry mass measurement and perform rapid bacterial detection at low concentrations. For drug-screening application, we demonstrate proof-of-concept antibiotic susceptibility testing and perform single-cell analysis of antibiotic-induced filamentation. The combination of high phase sensitivity, high spatiotemporal resolution, and large field of view is unique among existing microscopy techniques. As a quantitative and miniaturized platform, it can improve studies with microorganisms and other biospecimens at resource-limited settings.

[Visualization of normal ocular surface microflora via impression cytology sample using scanning electron microscopy with lanthanide contrasting]

PURPOSE

To determine the possibilities of impression cytology (IC) with subsequent visualization of the sample on a scanning electron microscope in assessment of normal microflora of the ocular surface.

MATERIALS AND METHODS

The article presents a visual characteristic of the microorganisms of the ocular surface (OS) captured during impression cytology (IC) in individuals without signs of inflammatory and degenerative eye diseases. The original method of staining the sample with heavy metal salts made it possible to identify the individual signs of the microorganisms in their subsequent visualization by scanning electron microscopy (SEM).

RESULTS

The paper presents photomicrographs of the microorganisms most common for the OS obtained with the help of SEM, confirming and supplementing the data of non-visual methods of studying the ocular microflora. It was shown that the detection frequency of the microbial component of the OS by the visual method presented in this study is comparable with the detection frequency when using the microbial cultivation method (<80%). Coccoid and rod-shaped microorganisms were detected with relatively equal frequency, with the coccoid organisms mainly represented in association with epithelial cells. The morphological diversity of rod-shaped microorganisms is shown.

CONCLUSION

The results of the study can be used as a visual reference for the normal microbiome of the eye.

Multi-purpose Disinfecting Solutions only Partially Inhibit the Development of Ocular Microbes Biofilms in Contact Lens Storage Cases

PURPOSE

Certain ocular resident or pathogenic microbes may remain viable in the presence of multi-purpose disinfectant solutions (MPDSs), subsequently developing biofilms inside contact lens storage cases (CLSCs) which pose a risk of infection to wearers. This study evaluated the formation of ocular microbiota biofilms exposed to three top selling MPDS.

METHODS

Crystal violet assay was carried out for the verification of biofilm formation. The in vitro assays evaluated Pseudomonas aeruginosa UFPEDA 416 and Staphylococcus aureus UFPEDA 02 exposure of 48 h to MPDS, as well as the use of 40 KHz ultrasound at the beginning and with 24 h immersion in the MPDS. Subsequently, in vivo assays evaluated the formation of microbial biofilms on the CLSC walls containing silicone-hydrogel contact lenses immersed in MPDS from 15 healthy volunteer patients, who had been wearing the lenses for 7 days.

RESULTS

Biofilms were inhibited by 26%-98% in the in vitro assays, with a statistically significant difference only for P. aeruginosa UFPEDA 416 exposed to diluted MPDS. Most inhibitions occurred moderately and weakly. In addition, adherent cells were detected in more than 90% of the tests. Biofilm was not inhibited in more than one third of the results, nor was it disturbed, especially with the ultrasound treatments. The average of obtained optical densities at 590 nm was between 0.6 and 0.8 in the in vivo assays. The results were similar between the CLSC right and left wells. There was a correlation between microbial biofilm formation and the type of MPDS tested, with statistical difference between the three treatments.

CONCLUSION

MPDS promoted a partial inhibition of microbial biofilm formation but only one MPDS proved to be more effective in vitro and in vivo. This study, however, could not distinguish the effect of possible errors in the good hygiene practices of the users.

Effect of Water Exposure on Contact Lens Storage Case Contamination in Soft Lens Wearers

SIGNIFICANCE

Water exposure during contact lens wear can transfer pathogenic microorganisms to the eye, causing ocular complications. This study determined that water exposure is prevalent among lens wearers and is independently associated with higher case contamination. Contact lens compliance education to minimize water exposure should be reenforced by contact lens organizations and practitioners.

PURPOSE

Given the increasing association between water exposure and contact lens disease, this study aimed to explore the effect of water exposure and storage case contamination in soft contact lens users.

METHODS

A total of 165 daily soft lens wearers completed a self-administered questionnaire on contact lens hygiene. Lens cases were collected, and microbial analysis was conducted using an adenosine triphosphate assay (for overall microbial bioburden) and limulus amebocyte lysate assay (for endotoxin levels). The lens hygiene (excellent, >35; moderate, 28 to 35; poor, <28) and water contact (≤1, good; >1, poor) scores measured the compliance and water exposure during lens wear, respectively. Multiple regression determined the association between water behaviors and case contamination.

RESULTS

The average (standard deviation) age of participants was 28 (13.5) years (18 to 78 years), and 65% were female. The average overall microbial bioburden of storage cases was 3.10 (0.98) log colony-forming unit/mL (1.09 to 5.94 log colony-forming unit/mL). Forty-five percent of participants reported showering, 49.7% reported swimming while wearing lenses (65.4% of whom swam without goggles), 27.8% used wet hands to handle lenses, and 17.5% used tap water to rinse storage cases. Showering with lenses significantly increased the risk of higher storage case bioburden (P = .001), whereas using wet hands (P = .01) doubled the risk of higher case endotoxin levels (odds ratio, 2.41; confidence interval 1.19 to 4.86).

CONCLUSIONS

Water contact behavior while wearing lenses is prevalent among soft lens wearers and is associated with higher case contamination. Practitioners may improve contact lens education to reduce water exposure and case contamination to reduce the risk of lens-related adverse events.

ZnO/CPAN Modified Contact Lens with Antibacterial and Harmful Light Reduction Capabilities

Compared with traditional glasses, the comfortable and convenient contact lens (CL) has seen an upsurge among the public. However, due to the lack of antibacterial properties of ordinary CLs, the risk of eye infection is greatly increased accordingly. On the other hand, ordinary CLs also cannot effectively reduce the short-wavelength blue light emitted from electronic products, such as mobile phones and computers. Aiming at the above two problems, zinc oxide (ZnO)/cyclized polyacrylonitrile (CPAN) composites are developed for CL modification. After loading with ZnO/CPAN (ZC), the CL shows a broad-spectrum antibacterial property. Further experiments also prove that it can block UVB, UVA, as well as blue light selectively, under the premise of ensuring hydrophilicity and certain transparency. Theoretically, this ZC-decorated CL can fundamentally reduce the damage to the eyes from harmful light emitted by light-emitting diodes and the secretion of pro-inflammatory factors, which is thus a promising eye protection strategy for modern society.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

pHEMA: An Overview for Biomedical Applications

Poly(2-hydroxyethyl methacrylate) (pHEMA) as a biomaterial with excellent biocompatibility and cytocompatibility elicits a minimal immunological response from host tissue making it desirable for different biomedical applications. This article seeks to provide an in-depth overview of the properties and biomedical applications of pHEMA for bone tissue regeneration, wound healing, cancer therapy (stimuli and non-stimuli responsive systems), and ophthalmic applications (contact lenses and ocular drug delivery). As this polymer has been widely applied in ophthalmic applications, a specific consideration has been devoted to this field. Pure pHEMA does not possess antimicrobial properties and the site where the biomedical device is employed may be susceptible to microbial infections. Therefore, antimicrobial strategies such as the use of silver nanoparticles, antibiotics, and antimicrobial agents can be utilized to protect against infections. Therefore, the antimicrobial strategies besides the drug delivery applications of pHEMA were covered. With continuous research and advancement in science and technology, the outlook of pHEMA is promising as it will most certainly be utilized in more biomedical applications in the near future. The aim of this review was to bring together state-of-the-art research on pHEMA and their applications.

Influence of Contact Lens Materials and Cleaning Procedures on Bacterial Adhesion and Biofilm Formation

Purpose

The present study aimed to compare the existing soft contact lens (CL) materials regarding their influence on bacterial biofilm formation and adhesion susceptibility. Then, the study was designed to investigate the effectiveness of various disinfecting solutions and evaluate the ability of cleaning regimens in terms of anti-bacterial adhesion and biofilm removal on different soft CL materials.

Methods

Bacterial biofilm formation on CLs was evaluated by biomass assay. Adhesion assay and standard plate count were carried out at time-interval periods within 24 h. Various CL disinfecting procedures were assessed for their efficacy to remove biofilm and reduce bacterial adhesion. Scanning electron microscopy (SEM) was performed for the morphological assessment of bacterial biofilm.

Results

Printed hydroxyethyl methacrylate (HEMA) CLs significantly demonstrated more biofilm staining and bacterial attachment when compared with non-printed HEMA CLs, while the Filcon II 3 and Nesofilcon A CLs possessed less biofilm biomass and adherent cells. Staphylococcus aureus and Pseudomonas aeruginosa represented the highest biofilm producing bacteria on HEMA-based materials in this study. The disinfecting regimen with the highest efficacy was the two-step system, first using multipurpose disinfecting solution containing edetate disodium and sorbic acid (MPDS+EDSA), followed by soaking in multipurpose solution (MPS). The regimen demonstrated the greatest effect against the pre-formed biofilm and the adhesion activity of S. aureus and P. aeruginosa on the soft CLs. The SEM micrographs confirmed the morphological changes of bacterial biofilm after disinfecting and revealed that the two-step system treated CLs displayed less adherent bacteria.

Conclusion

HEMA-based soft CLs may facilitate bacterial biofilm formation and adhesion capability. The two-step system was the most effective regimen for biofilm removal, where the soaking period in the disinfecting solution of the no-rub regimen should last more than 6 h to remove pre-formed biofilm.

Ocular Surface Microbiota in Contact Lens Users and Contact-Lens-Associated Bacterial Keratitis

Our objectives were to investigate whether the conjunctival microbiota is altered by contact lens wear and/or bacterial keratitis and to explore the hypothesis that commensals of conjunctival microbiota contribute to bacterial keratitis. Swab samples from both eyes were collected separately from the inferior fornix of the conjunctiva of non-contact-lens users (n_participants = 28) and contact lens users (n_participants = 26) and from patients with contact-lens-associated bacterial keratitis (n_participants = 9). DNA from conjunctival swab samples was analyzed with 16S rRNA gene amplicon sequencing. Pathogens from the corneal infiltrates were identified by cultivation. In total, we identified 19 phyla and 283 genera; the four most abundant genera were Pseudomonas, Enhydrobacter, Staphylococcus, and Cutibacterium. Several pathogens related to bacterial keratitis were identified in the conjunctival microbiota of the whole study population, and the same bacteria were identified by both methods in the conjunctiva and cornea for four patients with contact-lens-associated bacterial keratitis. The overall conjunctival microbiota profile was not altered by contact lens wear or bacterial keratitis; thus, it does not appear to contribute to the development of bacterial keratitis in contact lens users. However, in some individuals, conjunctival microbiota may harbor opportunistic pathogens causing contact-lens-associated bacterial keratitis.

Factors Affecting Microbial Contamination on the Back Surface of Worn Soft Contact Lenses

SIGNIFICANCE

The results of this study demonstrate that Smart Touch Technology packaging, which is designed to reduce and simplify contact lens handling before insertion, is effective in reducing the frequency of bacterial contamination of the back surface of contact lenses after short-term wear.

PURPOSE

The purpose of this study was to investigate the effect of lens packaging type, chelating agent, and finger contamination on microbial contamination on the back surface of worn soft contact lenses.

METHODS

Twenty-five subjects completed each contralateral lens wear comparison in this randomized study: Smart Touch Technology versus conventional blister packaging for (1) silicone hydrogel lenses with ethylenediaminetetraacetic acid (EDTA) and (2) hydrogel lenses without EDTA in the packaging, and (3) silicone hydrogel lenses without EDTA versus hydrogel lenses with EDTA both in Smart Touch Technology packaging. Participants washed hands, underwent finger swabs, and inserted the lenses. After 45 minutes, lenses were removed aseptically and the posterior lens surfaces cultured.

RESULTS

Thirty-eight subjects (average age, 30.9 ± 12.5 years) participated in this study. Overall, the level of back surface contamination was low for both lens materials, ranging from 0 to 43 colony-forming unit (CFU)/lens for the silicone hydrogel and 0 to 17 CFU/lens for the hydrogel lenses. The proportion of lenses with zero back surface contamination ranged from 16 to 64% for silicone hydrogel lenses and 28 to 64% for hydrogel lenses. Contact lenses from conventional packaging containing EDTA had 3.38 times increased risk (95% confidence interval [CI], 1.02 to 11.11; P = .05) of contamination being present compared with lenses from Smart Touch packaging with EDTA. Contact lenses from conventional packaging without EDTA had 3.4 times increased risk (95% CI, 1.02 to 11.36; P = .05) of contamination being present compared with Smart Touch packaging without EDTA, and silicone hydrogel lenses had a 6.28 times increased risk (95% CI, 1.65 to 23.81; P = .007) of contamination being present compared with hydrogels. The median (interquartile range) number of bacteria isolated from fingers used to perform lens insertion after handwashing but before lens insertion was not significantly different between the silicone hydrogel and hydrogel lenses (63.7 [204.2] vs. 59 [84.5], P = .09). Finger contamination was not significantly associated with lens contamination in the presence or absence of EDTA.

CONCLUSIONS

Smart Touch Technology packaging was effective in reducing the proportion of contaminated lenses. Although silicone hydrogel lenses were more likely to be contaminated, the presence of EDTA ameliorated this effect. Finger contamination was not associated with lens contamination.

Technical Report: Guidelines for Handling of Multipatient Contact Lenses in the Clinical Setting

SIGNIFICANCE

Standardized guidelines that are clinically practical are needed to assist the prescriber in minimizing the risk of conveying infection through multiuse diagnostic contact lens use and reuse.Contact lens prescribers face the specter of transferring potential pathogens from one patient to another when reusing diagnostic (trial) contact lenses on multiple patients because infectious organisms have been recovered from worn contact lenses, although there is no evidence of transmission through this mechanism. These pathogens can be introduced into the system from one patient to another, or they may be introduced by clinician lens handling, storage, or both. These pathogens can cause acute or chronic systemic or ocular infection that can lead to significant morbidity (temporary or permanent) that includes vision loss.

CLEAR - Evidence-based contact lens practice

Evidence-based contact lens -->practice involves finding, appraising and applying research findings as the basis for patient management decisions. These decisions should be informed by the strength of the research study designs that address the question, as well as by the experience of the practitioner and the preferences and environment of the patient. This reports reviews and summarises the published research evidence that is available to inform soft and rigid contact lens history and symptoms taking, anterior eye health examination (including the optimised use of ophthalmic dyes, grading scales, imaging techniques and lid eversion), considerations for contact lens selection (including the ocular surface measurements required to select the most appropriate lens parameter, lens modality and material selection), evaluation of lens fit, prescribing (teaching self-application and removal, adaptation, care regimen and cleaning instructions, as well as -->minimising risks of lens wear through encouraging compliance) and an aftercare routine.

CLEAR - Contact lens technologies of the future

Contact lenses in the future will likely have functions other than correction of refractive error. Lenses designed to control the development of myopia are already commercially available. Contact lenses as drug delivery devices and powered through advancements in nanotechnology will open up further opportunities for unique uses of contact lenses. This review examines the use, or potential use, of contact lenses aside from their role to correct refractive error. Contact lenses can be used to detect systemic and ocular surface diseases, treat and manage various ocular conditions and as devices that can correct presbyopia, control the development of myopia or be used for augmented vision. There is also discussion of new developments in contact lens packaging and storage cases. The use of contact lenses as devices to detect systemic disease has mostly focussed on detecting changes to glucose levels in tears for monitoring diabetic control. Glucose can be detected using changes in colour, fluorescence or generation of electric signals by embedded sensors such as boronic acid, concanavalin A or glucose oxidase. Contact lenses that have gained regulatory approval can measure changes in intraocular pressure to monitor glaucoma by measuring small changes in corneal shape. Challenges include integrating sensors into contact lenses and detecting the signals generated. Various techniques are used to optimise uptake and release of the drugs to the ocular surface to treat diseases such as dry eye, glaucoma, infection and allergy. Contact lenses that either mechanically or electronically change their shape are being investigated for the management of presbyopia. Contact lenses that slow the development of myopia are based upon incorporating concentric rings of plus power, peripheral optical zone(s) with add power or non-monotonic variations in power. Various forms of these lenses have shown a reduction in myopia in clinical trials and are available in various markets.

Bacteriostatic Effect of Multidose Preservative-free Buffered Saline Used in Scleral Lens Wear

SIGNIFICANCE

Scleral lenses have become an increasingly common treatment for ocular surface disease and irregular corneas. Multidose, preservative-free saline solutions are frequently used off-label to fill scleral lenses. Because the fluid resides over the ocular surface during lens wear, contaminated solutions may increase the risk of infectious complications.

PURPOSE

We sought to assess the viability of skin microorganisms and pathogens associated with keratitis once introduced into a multidose preservative-free saline (MDPFS) solution containing the bacteriostatic agent boric acid (PuriLens Plus; The Lifestyle Co., Inc., Freehold, NJ).

METHODS

Eleven bacterial and one yeast isolate were each inoculated to three lots of MDPFS as well as to sterile normal saline for comparison. Microorganism concentrations were enumerated at baseline and days 1, 3, 7, 14, 21, and 28. Persistence of microorganism viability was compared between MDPFS lots and between MDPFS and normal saline for each organism.

RESULTS

Duration of microorganism viability was ≥24 hours in MDPFS with no significant difference in the distribution of survival duration of microorganisms in MDPFS versus normal saline (P = .15). Candida albicans concentrations declined 14 days earlier in MDPFS, whereas concentrations of viable organisms in MDPFS remained within 1 log of baseline for the longest durations for Pseudomonas aeruginosa (7 days), Escherichia coli (14 days), and Achromobacter xylosoxidans (≥28 days). Gram-positive organism concentrations remained within 1 log of baseline for no more than 3 days. Mild lot-to-lot variation in organism concentrations was noted near the end points of viability. Bacteriostasis was demonstrated in that concentrations of all organisms remained at or below baseline levels throughout the 28-day period.

CONCLUSIONS

After microbial contamination, persistence of organism viability was similar in PuriLens and normal saline. Environmental gram-negative organisms, many of which can contribute to infectious keratitis, can persist for weeks once introduced into saline solutions.

Current understanding and therapeutic management of contact lens associated sterile corneal infiltrates and microbial keratitis

Contact lenses are widely prescribed in clinical practice with multiple applications and advantages. However, contact lenses can be associated with various complications which range from innocuous to severe. Clinicians thus not only need to possess the ability to prescribe the most appropriate contact lenses for each individual patient but also be able to recognise and manage any associated complications. This review examines the existing literature on the management of corneal infiltrative events associated with soft contact lenses, including microbial keratitis, particularly in the context of practising in Australia. The definitions and diagnosis of corneal infiltrative events, as well as the current understanding of their aetiologies, will be explored. The various aspects of a successful management will be discussed, including the applications of therapeutic agents such as antimicrobial and anti-inflammatory agents, the role of microbiological investigations, and strategies to improve long-term prognosis. The currently available evidence supporting management options will be presented, highlighting the relative abundance of high-level evidence on management protocols, antimicrobial selection and treatment duration for microbial keratitis; and the relative paucity of studies and trials for sterile corneal infiltrative events, despite this condition being much more commonly encountered in clinical practice.

Microbiological Evaluation of Opened Saline Bottles for Scleral Lens Use and Hygiene Habits of Scleral Lens Patients

SIGNIFICANCE

Scleral lenses have become a widely used treatment option for patients with irregular corneas and ocular surface disease. Successful wear entails use of a nonpreserved saline solution to fill the lens before application on the eye.

PURPOSE

The purposes of this study were to evaluate solution from opened bottles of multidose preservative-free saline for microbiological growth and to better understand study participant hygiene habits while handling these bottles for scleral lens wear.

METHODS

Eligible study participants in this single-center prospective study were patients who routinely used multidose preservative-free saline solution for scleral lens rinsing and filling. Study participants completed a 12-question survey regarding their scleral lens hygiene habits and donated their opened multidose preservative-free saline bottle (PuriLens Plus; The Lifestyle Company, Inc., Freehold, NJ), which was processed for bacterial and fungal cultures.

RESULTS

Thirty-five participants (19 males, 16 females) with ages ranging from 6 to 81 years (mean, 47.9 years) were included. Indications for scleral lens wear included those with irregular corneas and ocular surface disease. The overall rate of microbial contamination among saline samples was 62.9% (n = 22). Twenty-one different microorganisms were identified. The survey responses did not differ significantly (P > .05) for any of the questions with regard to likelihood of positive culture. There were no significant age or sex differences between participants with positive or negative culture results. No significant differences were found between isolation of specific microorganisms and any of the survey responses.

CONCLUSIONS

This study suggests that off-label multidose preservative-free saline commonly used to rinse and fill scleral lenses before application on the eye may become contaminated with microorganisms once the bottle has been opened. Eye care practitioners and scleral lens patients should be aware of these potential contaminations and prioritize lens, hand, and environmental hygiene to minimize the risk of ocular complications.

American Academy of Optometry Microbial Keratitis Think Tank

SIGNIFICANCE

Think Tank 2019 affirmed that the rate of infection associated with contact lenses has not changed in several decades. Also, there is a trend toward more serious infections associated with Acanthamoeba and fungi. The growing use of contact lenses in children demands our attention with surveillance and case-control studies.

PURPOSE

The American Academy of Optometry (AAO) gathered researchers and key opinion leaders from around the world to discuss contact lens-associated microbial keratitis at the 2019 AAO Annual Meeting.

METHODS

Experts presented within four sessions. Session 1 covered the epidemiology of microbial keratitis, pathogenesis of Pseudomonas aeruginosa, and the role of lens care systems and storage cases in corneal disease. Session 2 covered nonbacterial forms of keratitis in contact lens wearers. Session 3 covered future needs, challenges, and research questions in relation to microbial keratitis in youth and myopia control, microbiome, antimicrobial surfaces, and genetic susceptibility. Session 4 covered compliance and communication imperatives.

RESULTS

The absolute rate of microbial keratitis has remained very consistent for three decades despite new technologies, and extended wear significantly increases the risk. Improved oxygen delivery afforded by silicone hydrogel lenses has not impacted the rates, and although the introduction of daily disposable lenses has minimized the risk of severe disease, there is no consistent evidence that they have altered the overall rate of microbial keratitis. Overnight orthokeratology lenses may increase the risk of microbial keratitis, especially secondary to Acanthamoeba, in children. Compliance remains a concern and a significant risk factor for disease. New insights into host microbiome and genetic susceptibility may uncover new theories. More studies such as case-control designs suited for rare diseases and registries are needed.

CONCLUSIONS

The first annual AAO Think Tank acknowledged that the risk of microbial keratitis has not decreased over decades, despite innovation. Important questions and research directions remain.

Dematiaceous fungal invasion of a bandage contact lens

A 61-year-old man presented with a 1-month history of reduced vision, redness and pain in the right eye. Examination revealed a bandage contact lens (BCL) in situ with diffuse, pigmented deposits. On removal, the underlying cornea was found to be clear. He had been prescribed the BCL 6 months ago following a deep-seated corneal foreign body removal and was unable to follow-up subsequently.The BCL was sent for microbiological and histopathological evaluation. The culture revealed growth of Cladosporium spp, a dematiaceous fungi. Periodic acid-Schiff staining revealed infiltration of pigmented fungal filaments into the substance of the BCL.While contact lens deposits are a frequent finding, fungal deposits are seldom noted. Irregular follow-up and improper lens maintenance are significant risk factors for the same. Early identification and subsequent removal of the lens is vital to prevent infection of the underlying ocular structures.

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

PURPOSE

To 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.

METHODS

Participants, 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.

RESULTS

Of 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.

CONCLUSIONS

Disinfection 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.