Microbial contamination of contact lenses and lens care accessories of soft contact lens wearers (university students) in Hong Kong

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.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

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.

Comparison of compliance with care procedures performed by orthokeratology wearers and their parents and factors affecting compliance

PURPOSE

To compare the levels of compliance with care routines of orthokeratology (ortho-k) wearers and their parents and to identify factors affecting compliance in a hospital setting in Chengdu, China.

METHODS

Patients who had worn ortho-k lenses for at least one month were invited to participate in a survey on compliance. Wearers or their parents were required to complete a questionnaire to determine their compliance with hand hygiene, ortho-k lenses and accessory care procedures.

RESULTS

A total of 200 wearers, 78 male wearers and 122 female wearers, median age 12 (range 8-18) years were enrolled. Except for use of lens solution, the percentage of participants reporting total compliance with all procedures did not differ significantly between lens wearers and their parents. However, compliance for some items was significantly higher when performed by parents p < 0.001-0.01). 'Eye care practitioner provided instructions' was a significant protective factor for most procedures (p < 0.001-0.04). Age and sex were significant risk factors for some items (p < 0.001-0.04; p = 0.03-0.04, respectively), with girls having higher compliance than boys. 'Parental supervision' was a significant protective factor for some items (p = 0.02-0.04) when wearers performed the procedures themselves. When parents performed lens care procedures, only 'eye care practitioner provided instructions' was a significant variable (p = 0.001-0.04).

CONCLUSION

Some degree of non-compliance was noted in the majority of ortho-k wearers, particularly for the care of the lens case and suction holder. Compliance with care of some items was higher when performed by parents. Regular reinforcement of care procedures by practitioners is important, especially for older and male lens wearers. Parental supervision is necessary when children perform lens care procedures themselves, even for older wearers.

Exploring microwave irradiation as a method to disinfect contact lens cases

PURPOSE

Biofilm formation caused by infrequent contact lens case replacement and the ineffectiveness of multi-purpose solutions (MPS) on biofilm removal is associated with high rates of bacterial keratitis infections. This study demonstrated biofilm elimination from the contact lens case by microwave irradiation.

METHODS

Staphylococcus aureus biofilms indicative of 3-9 months of contact wear were cultured in contact lens cases and visualized with crystal violet (CV) staining. Biofilms in contact cases were then exposed to four treatment regimens: No treatment (n = 8), 45 s microwave irradiation (n = 8), tap water (n = 6), and MPS (n = 9). Bacterial survival was assessed by colony forming unit (CFU) assay using streak dilutions.

RESULTS

Visualization of the biofilms through CV staining revealed that biofilms coalesce between ribs of the contact case. In 5/8 cases no CFU were cultivated from the case after treatment with microwave irradiation. In tap water and MPS the first dilution averaged 6 ± 2 and 31 ± 13 CFUs per plate, respectively, while microwave irradiation averaged < 1 CFU per plate. In Dilution 2, the average reduced to 0.7 ± 0.7 and 6 ± 5 CFUs per plate for tap water and MPS, respectively, while microwave irradiation had 0 CFUs in Dilution 2.

CONCLUSION

Biofilms that coalesce between the ribs of the contact case pose a threat because this area is difficult to thoroughly scrub and could act as a basis for infection through fouling of contact lenses. Of the four treatment regimens, microwave irradiation displayed the most consistent and highest rate of bacterial eradication. Tap water was less effective compared to microwave irradiation, and poses other harmful side effects, but greatly reduced CFU count compared to no treatment. MPS displayed the poorest bacterial eradication of the treatments. Thus, microwave irradiation is worth further investigation as a viable in-home disinfecting option.

Regular soft contact lens wearers' comprehension of graphical symbols labelled on multipurpose solutions

CLINICAL RELEVANCE

Symbols are commonly used to represent information of health care products included multipurpose solutions (MPSs) for contact lens (CL) care.

BACKGROUND

Little knowledge is available about recognition and comprehension by regular soft CL wearers of commonly used symbols in the instructions of CL MPSs marketed worldwide.

METHODS

CL wearers from the UK and Spain were invited to answer an anonymous on-line questionnaire (distributed though Facebook and Twitter) concerning the recognition and comprehension of seven common symbols (ISO 15223:2017 and EN 980:2008) included in MPS package instructions.

RESULTS

Answers of one hundred-ten soft CL wearers who use MPS (27 in the UK and 83 in Spain) were analysed showing low recognition and comprehension of the surveyed symbols even in wearers with > 5 years of CL wear (71.8%). The CE marked was the most recognised (96% in the UK and 88% in Spain, P = 0.29) and understood (78% in the UK and 85% in Spain, P = 0.25) symbol, but other important symbols, such as 'Caution' and 'Do not reuse', were under recognised (22% in the UK and 19% in Spain, P = 0.78 and 11% in the UK and 6% in Spain, P = 0.40 respectively) and understood (close to 30% in both countries P > 0.15). Participants with > 5 years of experience, showed slightly higher comprehension (P < 0.05) in some symbols ('Sterilised'; 'Do not reuse'; 'Use by date' and 'CE marked').

CONCLUSION

These results suggest an insufficient comprehension of seven common symbols included in MPS instructions among regular CL wearers in the UK and Spain without high impact of CL wear experience. Improving the education and symbol comprehension of regular CL wearers could help to get better patients' behaviour and safe use of MPS in soft CLs care.

Effect of Hygiene Procedures on Lens Case Contamination with Povidone-Iodine or Multipurpose Disinfecting Solutions

SIGNIFICANCE

A multipurpose disinfecting solution (MPDS), which contains povidone-iodine (PI) as a disinfectant, has high disinfecting efficacy not only on planktonic bacterium but also on the case biofilms. The addition of case hygiene practice removed more bacteria from cases than MPDS alone.

PURPOSE

This study compared the ability of two MPDSs, one containing PI and another containing polyaminopropyl biguanide and polyquaternium, to reduce bacterial numbers in solution or adhered to the cases following case hygiene procedures.

METHODS

Bacterial strains (Delftia acidovorans, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis) were exposed to the MPDSs for the recommended disinfection times, and the viable number evaluated according to ISO 14729. Cases were inoculated with bacterial strains and incubated for 24 hours to allow for biofilm formation. Cases were disinfected with both disinfecting solutions for 4 hours and rinsed, followed by recapping or air-drying, or tissue-wiping and air-drying for 18 hours. The number of survivors was counted using standard culture techniques.

RESULTS

Both products exceeded the recommended 3-log reduction against planktonic bacteria. Regarding biofilm, after rinsing and recapping wet, the numbers of D. acidovorans (mean difference [95% confidence interval] log10 colony-forming units per case, -2.9 [0.8 to -4.6], P < .01), P. aeruginosa (-2.0 [0.5 to -3.1], P < .01), S. marcescens (-1.7 [0.8 to -3.5], P < .05), and S. epidermidis (-2.1 [0.6 to -3.5], P < .05) in PI cases were significantly lower than in the dual-disinfectant MPDS storage cases. After air-drying, the PI storage cases had significantly lower numbers of S. maltophilia (-2.6 [0.6 to -4.0], P < .01), D. acidovorans (-1.6 [0.7 to -3.3], P < .05), and S. aureus (-1.6 [0.7 to -3.1], P < .05). The addition of tissue-wiping reduced the bacterial numbers in the MPDS storage cases to levels in the PI storage cases.

CONCLUSIONS

Contact lens users should be recommended to tissue-wipe and air-dry their lens storage cases after disinfection with regular MPDS.

The effect of a compliance enhancement strategy (self‐review) on the level of lens care compliance and contamination of contact lenses and lens care accessories

PURPOSE

The aims were to determine the level of compliance of contact lens wearers, to identify which procedures have highest levels of non-compliance and to study the effectiveness of a compliance enhancement strategy on the level of compliance.

METHODS

The level of compliance for each subject was evaluated with a self-administered questionnaire together with microbiological examination of their contact lenses, lens cases and lens care solutions. The effect of an intervention to improve the level of compliance was determined by a controlled trial. A regular self-review exercise on proper lens handling was given to the test group once every three months for 12 months. The levels of compliance and contamination of contact lenses and lens care accessories between test and control groups were compared at the end of the 12-month period to evaluate the effect of the intervention.

RESULTS

Sixty-five subjects who were experienced contact lens wearers were recruited and 60 completed the study. All showed some degree of non-compliance in the care of their contact lenses and lens accessories. Most (about 60 per cent) were non-compliant with at least six of a total of 15 lens care procedures. The most common non-compliant behaviour among contact lens wearers was associated with the care of the lens case. By the end of the study period, our compliance enhancement strategy did not appear to have had a significant effect on the behaviour of our subjects, except for improvement in the care of lens cases. Compliance for other procedures improved in both test and control groups.

CONCLUSION

All subjects showed some degree of non-compliance and the spectrum of non-compliance was wide. The poorest levels of compliance were associated with care of the lens case, which was also the most frequently contaminated item. Our compliance enhancement strategy showed a significant difference in improvement in compliance between the intervention and control groups only in the care of lens cases.

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

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

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

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

Development of a contact Lens risk survey

PURPOSE

To describe the development and report psychometric properties of the Contact Lens Risk Survey (CLRS) to identify patients at risk for soft contact lens-related complications.

METHODS

Psychometric properties of the CLRS, a web-based survey with branching logic, were determined using data from 5 multi-site fieldings (n = 1059), including re-fielding to sub groups. Responses from participants with and without an active red eye were used to identify risk factors of a red eye event and calculate an overall risk score. A 6th fielding of the CLRS (n = 171) was used to assess discriminate validity.

RESULTS

Participants needed 11-12 min to complete the survey with a negligible difference by age. Internal consistency was excellent (Cronbach's α ≥ 0.70) for 3 of the 5 constructs identified by factor analysis. Twelve of the 17 survey items exhibited excellent within-subject repeatability (Kappa ≥ 0.61). Between-subject agreement, assessed in 18-25 year olds, was high for the majority of items, suggesting good generalizability across different populations of SCL wearers. The ability of the model using individual items of the CLRS to discriminate Controls and participants with a red eye was good with an area under the curve of 0.779.

CONCLUSION

The CLRS tool is a repeatable and valid instrument to standardize documentation of demographic, behavior, and exposure factors which appear to drive the greatest risk of a contact lens related red eye event.

Contact lens wear and care in Spain during the COVID-19 pandemic

AIM

To establish contact lens wear and care practices during the COVID-19 pandemic in Spain.

METHOD

A 58-item anonymous online survey was distributed during the period 30th April to 10th May via Qualtrics. The survey explored: a) demographic characteristics (age, sex, general health and where they were living during lockdown), b) changes in their contact lens use during lockdown, c) hygiene and contact lens compliance and d) concerns associated with contact lens wear and ways to support wearers during the pandemic.

RESULTS

Two hundred and sixty responses were analysed (38.8 ± 11.4 years old, 75% female). Three-quarters of participants reported that they were self-isolating or rigorously following social distancing advice. Sixty-seven percent of participants reported using their contact lenses less during the pandemic. Respondents were found to be compliant with handwashing prior to inserting and removing contact lenses (in both cases 97% doing this 'most times' or 'every time'). However, only 44 % complied with the '20 s rule' and 48 % used a shared towel to dry their hands. A higher proportion of hydrogen peroxide users replaced the lens case monthly compared to multi-purpose users (64% vs.49%; p < 0.001). Twenty-four percent admitted wearing lenses whilst showering and 16% did not consider ceasing lens wear if feeling unwell with flu/cold symptoms.

CONCLUSION

Eye care practitioners should continue to educate contact lens wearers to ensure safe contact lens wear to minimise the chance of developing contact lens related complications during the pandemic. Modifiable factors that need particular attention in Spain include: handwashing for at least 20s before lens handling, drying hands with single use paper towels, including a rub-and-rinse step for reusable lenses, lens case cleaning and renewal, avoidance of water exposure and when to cease lens wear during the pandemic.

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

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

A study of contact lens compliance in a non-clinical setting

PURPOSE

To evaluate soft contact lens replacement, overnight (ON) wear, and contact lens case compliance in a non-clinical sample.

METHODS

Subjects (n = 297) were recruited at the Center for Science and Industry (COSI) in Columbus, Ohio. Adult (≥ 18 years) soft contact lens wearers completed a survey about contact lens replacement, ON contact lens wear, and contact lens case replacement habits.

RESULTS

Two-week replacement lenses (according to the manufacturer's replacement schedule [MRS]) were most common (45.5%), followed by monthly (34.3%) and daily replacement (20.2%). Non-compliance with replacement schedule was reported in 38.7% of subjects. Age (p = 0.02), years of lens wear (p = 0.02), and MRS (p <0.0001) affected replacement compliance. Post-hoc analysis showed daily replacement wearers were more compliant than two-week (p <0.0001) and monthly (p <0.0001) replacement wearers with prescribed lens replacement. Non-compliance with prescribed ON wear was reported in 23.9% of subjects. Subjects who were non-compliant with lens replacement were more likely to be non-compliant with ON wear (p = 0.02) and had worn contact lenses for less time (p = 0.02). Of the subjects who used contact lens cases, 74.6% were unsure when they should replace their case. Frequency of case replacement was not associated with age (p = 0.5), gender (p = 0.5), years of contact lens wear (p = 0.7), MRS (p = 0.4), replacement compliance (p = 0.3), or ON wear compliance (p = 0.7).

CONCLUSIONS

Daily replacement wearers were most likely to be compliant with contact lens replacement, but all subjects, including daily replacement wearers, had similar ON wear non-compliance. Non-compliant lens replacement was associated with non-compliant ON wear, but contact lens case replacement was not related to either compliance category. The majority of subjects had no knowledge of proper contact lens case replacement, despite compliance in other categories.

Contact Lens Technology: From Fundamentals to Applications

Contact lenses are ocular prosthetic devices used by over 150 million people worldwide. Primary applications of contact lenses include vision correction, therapeutics, and cosmetics. Contact lens materials have significantly evolved over time to minimize adverse effects associated with contact lens wearing, to maintain a regular corneal metabolism, and to preserve tear film stability. This article encompasses contact lens technology, including materials, chemical and physical properties, manufacturing processes, microbial contamination, and ocular complications. The function and the composition of the tear fluid are discussed to assess its potential as a diagnostic media. The regulatory standards of contact lens devices with regard to biocompatibility and contact lens market are presented. Future prospects in contact lens technology are evaluated, with particular interest given to theranostic applications for in situ continuous monitoring the ocular physiology.

In Vitro Antimicrobial Efficacy of Silver Lens Cases Used With a Multipurpose Disinfecting Solution

Purpose

We evaluate the in vitro antibacterial activity of silver-copolymerized barrel cases compared to nonsilver barrel cases in combination with a multipurpose disinfecting solution (MPDS).

Methods

The ability of silver and nonsilver cases to reduce the number of adherent Gram-positive and Gram-negative bacteria was assessed. Additionally, the efficacy of silver cases along with MPDS was investigated in the presence of organic soil and contact lenses. Contact lens cases were challenged with 10⁶ colony-forming units (CFU)/mL of five bacterial species. Adherent bacteria were dislodged from lens cases and surviving organisms enumerated.

Results

Significantly lower numbers of microbes were recovered from silver cases compared to controls, for all bacterial strains (P < 0.005). The combination of silver case along with MPDS showed added efficacy against Gram-positive and -negative bacteria with a maximum reduction of 3.00 ± 0.5 Log₁₀ CFU/mL, compared to the efficacy of silver cases alone (1.97 ± 0.4 Log₁₀ CFU/mL). The addition of organic soil and a contact lens resulted in a significant (P < 0.005) decrease (a maximum of 1.68 ± 0.2 log₁₀ CFU/mL) in disinfection efficacy when MPDS and either silver or control cases were used.

Conclusions

Silver-copolymerized barrel cases work on conjunction with a hypochlorite producing MPDS in the presence of contact lenses and organic soil to reduce microbial contamination of lens cases.

Transitional Relevance

Silver-copolymerized barrel contact lens cases show promising in vitro antibacterial activity against bacterial types commonly implicated in contact lens-related corneal infections. This intervention may limit storage case contamination during use and reduce the frequency of contact lens-related microbial disease.

Blowing epithelial cell bubbles with GumB: ShlA-family pore-forming toxins induce blebbing and rapid cellular death in corneal epithelial cells

Medical devices, such as contact lenses, bring bacteria in direct contact with human cells. Consequences of these host-pathogen interactions include the alteration of mammalian cell surface architecture and induction of cellular death that renders tissues more susceptible to infection. Gram-negative bacteria known to induce cellular blebbing by mammalian cells, Pseudomonas and Vibrio species, do so through a type III secretion system-dependent mechanism. This study demonstrates that a subset of bacteria from the Enterobacteriaceae bacterial family induce cellular death and membrane blebs in a variety of cell types via a type V secretion-system dependent mechanism. Here, we report that ShlA-family cytolysins from Proteus mirabilis and Serratia marcescens were required to induce membrane blebbling and cell death. Blebbing and cellular death were blocked by an antioxidant and RIP-1 and MLKL inhibitors, implicating necroptosis in the observed phenotypes. Additional genetic studies determined that an IgaA family stress-response protein, GumB, was necessary to induce blebs. Data supported a model where GumB and shlBA are in a regulatory circuit through the Rcs stress response phosphorelay system required for bleb formation and pathogenesis in an invertebrate model of infection and proliferation in a phagocytic cell line. This study introduces GumB as a regulator of S. marcescens host-pathogen interactions and demonstrates a common type V secretion system-dependent mechanism by which bacteria elicit surface morphological changes on mammalian cells. This type V secretion-system mechanism likely contributes bacterial damage to the corneal epithelial layer, and enables access to deeper parts of the tissue that are more susceptible to infection.

Level of Compliance in Orthokeratology

OBJECTIVES

To investigate the level of compliance with orthokeratology (ortho-k) guidelines and the main behaviors of poor compliance to guide clinical care.

METHODS

A questionnaire was sent to ortho-k patients in the Eye Hospital of Wenzhou Medical University (EHWMU) in Mainland China who were prescribed ortho-k lenses after January 2013 and have worn ortho-k lenses for more than 1 year to determine the compliance rate for eight wear and care behaviors. Follow-up visit compliance was then investigated among these patients using a retrospective survey.

RESULTS

A total of 1,500 questionnaires were distributed, and 405 patients responded. The mean age of the patients was 13.1±3.9 years (range 9-22 years); 60.5% of the patients were female, and 98.3% were younger than 18 years. The full compliance rate was 14.1%, the compliance rate for wear and care behaviors was 18.5%, and the compliance rate for follow-up visits was 63.3%. The three highest noncompliance categories for wear and care behaviors were exposure to nonsterile solution, not removing lens depositions according to the eye care practitioners' (ECPs) recommendations and inadequate hand washing. No correlation was observed between the compliance for wear and care behaviors and age, sex, and wearing experience. The follow-up visit compliance rate significantly decreased from the third month to the ninth month. The common reasons for discontinuing follow-up were lack of time, no symptoms, and inconvenience.

CONCLUSIONS

The level of compliance with ortho-k lens wear in Mainland China is not high, necessitating ECPs to stress to patients the details of wear and care behaviors, especially avoiding exposing lenses to nonsterile solution. Improving monitoring of follow-up visits, particularly within the first 9 months of wearing ortho-k lenses, is needed.

A Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2018 Update by the Infectious Diseases Society of America and the American Society for Microbiology

The critical nature of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician/advanced practice provider and the microbiologists who provide enormous value to the healthcare team. This document, developed by experts in laboratory and adult and pediatric clinical medicine, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. This document presents a system-based approach rather than specimen-based approach, and includes bloodstream and cardiovascular system infections, central nervous system infections, ocular infections, soft tissue infections of the head and neck, upper and lower respiratory infections, infections of the gastrointestinal tract, intra-abdominal infections, bone and joint infections, urinary tract infections, genital infections, and other skin and soft tissue infections; or into etiologic agent groups, including arthropod-borne infections, viral syndromes, and blood and tissue parasite infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. In addition, the pediatric needs of specimen management are also emphasized. There is intentional redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a guidance for physicians in choosing tests that will aid them to quickly and accurately diagnose infectious diseases in their patients.

Bacterial Coaggregation and Cohesion Among Isolates From Contact Lens Cases

Purpose

The aim of this study was to examine cohesion, coaggregation, and coculture between bacteria commonly isolated from contact lens cases.

Methods

Staphylococcus epidermidis, Staphylococcus haemolyticus, Micrococcus luteus, and Acinetobacter radioresistens (two strains each) isolated from contact lens cases of two asymptomatic wearers were used in this study. In the cohesion assay, bacteria were grown, washed, and examined by incubating lens cases with two different types of bacteria sequentially and assessing the number of adhered cells of each isolate. The ability of isolates to interfere with the growth of other isolates was tested by growing strains in cocultures for 24 hours and determining the numbers of cells of individual strains. For coaggregation, equal proportions of two bacterial suspensions were mixed and allowed to coaggregate for 24 hours. Inhibition of coaggregation was tested by the addition of lactose (0.06 M) or sucrose (0.06 M) or pronase.

Results

The initial adhesion of M. luteus or A. radioresistens significantly (P < 0.05) enhanced the subsequent adhesion of the staphylococci. The addition of A. radioresistens in liquid media significantly (P < 0.05) enhanced the growth of staphylococci. S. epidermidis or S. haemolyticus coaggregated with M. luteus or A. radioresistens. The degree of coaggregation varied between 30% and 54%. The highest coaggregation (54% ± 5%) was seen between A. radioresistens 22-1 and S. epidermidis 22-1, isolated from the same lens case. Only lactose or sucrose treatment of staphylococci could partly inhibit coaggregation of some pairs.

Conclusions

Coaggregation, cohesion, and growth promotion may facilitate the process of bacterial colonization of contact lens cases.

Epidemiology of contact lens-induced infiltrates: an updated review

Corneal infiltrative events (CIEs) are well established as a risk associated with soft contact lens wear. The incidence of symptomatic CIEs during extended soft lens wear ranges from 2.5 to six per cent; when asymptomatic CIEs are included, the incidence can be as high as 20-25 per cent. In daily soft lens wear, the annual incidence of symptomatic CIEs is about three per cent. There are various accepted methods of categorising CIEs, and a scoring system based on clinical signs and symptoms is a good approach to grade severity. Lens-related risk factors include extended wear, silicone hydrogel material, the use of multipurpose solutions, bacterial bioburden and reusable lenses. Recent studies report that daily disposable lenses reduce the risk of CIEs.

Disturbing the balance: effect of contact lens use on the ocular proteome and microbiome

Contact lens wear is a popular, convenient and effective method for vision correction. In recent years, contact lens practice has expanded to include new paradigms, including orthokeratology; however, their use is not entirely without risk, as the incidence of infection has consistently been reported to be higher in contact lens wearers. The explanations for this increased susceptibility have largely focused on physical damage, especially to the cornea, due to a combination of hypoxia, mechanical trauma, deposits and solution cytotoxicity, as well as poor compliance with care routines leading to introduction of pathogens into the ocular environment. However, in recent years, with the increasing availability and reduced cost of molecular techniques, the ocular environment has received greater attention with in-depth studies of proteins and other components. Numerous proteins were found to be present in the tears and their functions and interactions indicate that the tears are far more complex than formerly presumed. In addition, the concept of a sterile or limited microbial population on the ocular surface has been challenged by analysis of the microbiome. Ocular microbiome was not considered as one of the key sites for the Human Microbiome Project, as it was thought to be limited compared to other body sites. This was proven to be fallacious, as a wide variety of micro-organisms were identified in the analyses of human tears. Thus, the ocular environment is now recognised to be more complicated and interference with this ecological balance may lead to adverse effects. The use of contact lenses clearly changes the situation at the ocular surface, which may result in consequences which disturb the balance in the healthy eye.

Effect of the osmolarity change in multipurpose solutions induced by an improper contact lens case cleaning procedure

PURPOSE

To determine whether variations in multipurpose disinfecting solution (MPDS) storage osmolarity from inappropriate contact lens (CL) case cleaning affect ocular surface integrity and wearer comfort.

METHODS

There were twenty contact lens cases (study CLCs) in the study group. Ten were filled with ReNu Multiplus(®) and 10 with SoloCare Aqua™ (MPDS-1 and -2, respectively) and kept closed for 8h; the cases were then emptied and kept open for air-drying for 16h. This procedure was carried out every day for two months. Storage solution osmolarity was measured on days 0, 15, 30, 45 and 60. Ten subjects were then fitted with both month-old lenses stored in the study CLCs and with new lenses stored in new cases with fresh solution for 24h (control CLCs). Symptoms, tear osmolarity and percentage of subjects whose conjunctival hyperaemia and ocular surface staining scores changed were determined after 1h of wear.

RESULTS

Study CLC osmolarity increased in both solutions after two months (p<0.05). For MPDS-1 there were differences in stinging between study CLCs and control CLCs after 10min of CL wear (p=0.04), and in comfort after 10 (p=0.035) and 60min wear (p=0.042). Significant (p<0.05) differences between study CLC and control CLC groups were also found for MPDS-2 in limbal hyperaemia (study: 50% change; control: 0% change) and bulbar and corneal staining (study: 80% change; control: 20% change).

CONCLUSION

The stored-MPDS osmolarity increase caused by air-drying the CLCs could affect the ocular surface. This increase might reduce lens wear comfort.

Efficacy of multipurpose contact lens solutions against ESBL-positive Escherichia coli, MRSA, and Candida albicans clinical isolates

OBJECTIVES

The antimicrobial effects of multipurpose contact lens solutions (MPSs) have been evaluated according to ISO 14729 standards. The aim of this study was to assess the efficacy of commercially available MPSs against extended-spectrum beta lactamases (ESBL)-producing Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans clinical isolates.

METHODS

Three commercially available contact lens solutions (Opti-Free Expresss, ReNu MultiPlus, and Solo Care Aqua) were tested against 18 ESBL-positive E. coli clinical strains, 20 MRSA clinical strains, and 20 C. albicans clinical strains. The stand-alone assays for bacteria and fungi were performed according to ISO 14729 criteria, and all samples were evaluated after 2, 4, and 24 hours of incubation. The numbers of viable microorganisms were evaluated by the plate-counting method.

RESULTS

All MPSs demonstrated at least 3 log reduction in colony-forming units (CFU) for all bacterial isolates and 1 log reduction in CFU for all yeast isolates, which meets ISO 14729 standards. Although no statistically significant differences were obtained among MPSs for bacterial isolates, variable responses were observed against clinical isolates: 5% povidone-iodine was more effective compared with Solo Care Aqua for C. albicans clinical strains (P<0.05); and all solutions were effective after an incubation time of only 2 hrs. The MPSs showed good activity against S. aureus, E. coli, and C. albicans.

CONCLUSIONS

Although effective log reductions were provided with all MPSs, the reduction was variable depending on the strains tested. Multipurpose contact lens solutions should be tested under ISO 14729 standards for both standard and clinical strains.

Identification of coagulase-negative staphylococci in daily disposable contact lens wearers

This study aimed to identify and quantify the number of contaminating organisms on daily disposable (DD) soft contact lenses, which may be responsible for mild cases of keratitis that occur with this lens wear modality. Ten participants wore DD lenses, and 10 participants wore planned replacement (PR) lenses. Lenses were collected aseptically and analysed for microbial contamination. Colony-forming units (CFU) were recorded, and representative colonies were used for identification using the API identification system. The DD lenses evaluated in this study were contaminated with coagulase-negative staphylococcus (CNS), ranging from 1 to 653 CFU. PR lenses showed more diversity in the types of contaminating micro-organisms and consisted of CNS, Gram-negative bacteria (Pseudomonas), a yeast (Candida) and a mould (Aspergillus), ranging from 1 to 230 CFU. CNS was the only type of micro-organism found on DD contact lenses and therefore may be the cause of any form of keratitis observed in DD lens wearers.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study to determine the frequency and identify the contaminating organisms found on daily disposable (DD) soft contact lenses. The contaminating organisms identified on DD contact lenses were solely coagulase-negative staphylococcus (CNS), suggesting that CNS may be the causative organism associated with infectious keratitis that occurs with DD contact lens wear.

Effect of multipurpose solutions against Acinetobacter carrying QAC genes

PURPOSE

Acinetobacter has low virulence but causes infections in subjects with reduced immunity. It has been reported in ocular infections including those of patients using contact lenses. Treatment is difficult because Acinetobacter is frequently multidrug resistant. Antibiotic-resistant strains frequently also harbor genes for antiseptic resistance (quaternary ammonium compound [QAC]) genes. Because Acinetobacter is part of the normal flora, it may contaminate contact lens and accessories. This study aims to investigate carriage rates of QAC genes in household and clinical isolates of Acinetobacter and to determine the effectiveness of two multipurpose solutions (MPSs) for soft lenses against organisms carrying QAC genes.

METHODS

DNA was extracted from 11 bathroom isolates and 15 clinical isolates and amplified by polymerase chain reaction to determine the presence of qacEΔ1. Gene-positive and gene-negative control strains were used to challenge the two MPSs, and minimum inhibitory concentrations (MICs) of these organisms to benzalkonium chloride and chlorhexidine gluconate were determined.

RESULTS

More than 90% of isolates carried qacEΔ1. The MICs of clinical isolates were higher than those of isolates of bathrooms. Both MPSs were able to produce a 3-log reduction in the numbers of all isolates.

CONCLUSIONS

Although most isolates carried qacEΔ1 and elevated MICs to benzalkonium chloride and chlorhexidine gluconate were observed, all were susceptible to both MPSs tested. However, if there were to be poor compliance with care procedures, it is probable that such organisms could survive in the presence of diluted or expired solutions.

A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a)

The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.