Acanthamoeba Keratitis Associated With Tap Water Use During Contact Lens Cleaning

A snap-shot of orthokeratology lens rinsing habits: An online survey in a major eye hospital in Shanghai

PURPOSE

A hospital-based survey to explore lens rinsing habits of orthokeratology (ortho-k) patients, including the solution used for rinsing.

METHODS

An anonymous survey, via an online questionnaire, was administered to ortho-k lens wearers or their parents when they attended Fudan University Eye and ENT Hospital for routine follow-up visits. Three major issues were investigated: basic demographics, lens rinsing solution used, and specific rinsing habits. Relationships between demographics and rinsing solution used and rinsing behaviours were explored.

RESULTS

Of the total of 541 online questionnaires delivered, 296 were completed and returned. The respondents were the person responsible for lens care, either the ortho-k users themselves, or their parents. The median age of the lens wearers was 12.0 years (range: 8-22 years), and the median period of ortho-k lens wear was 18.0 months (range: 1-109 months). The most common rinsing solutions reported were a particular brand of multidose preserved saline (28.4%), cooled boiled water (23.3%), and non-preserved multidose saline (16.2%). Overall, the main reason for choice of rinsing solution was recommendation of eye care practitioners (90.2%). The respondents with a longer lens wear history tended to use commercially available bottled water, drinking water, or cooled boiled water rather than non-preserved saline (unidose or multidose) (p ≤ 0.009) and were more likely to use the rinsing solution to soak their lenses (p = 0.009). Lens wearers who rinsed the lenses themselves tended to use tap water compared to those whose lenses were handled by parents (p = 0.040).

CONCLUSION

Inappropriate choice and usage of rinsing solution appeared to be a common issue among ortho-k lens wearers in Shanghai, China. The problem was more pronounced in long-term wearers and in those who performed rinsing themselves.

Evaluation of Rinsing Options for Rigid Gas Permeable Contact Lenses

OBJECTIVES

This study assessed the efficacy of various saline solutions as alternative methods to rinsing rigid gas permeable (RGP) lenses with tap water.

METHODS

The exiting fluid pressure of five commercially available saline solutions was measured using a venous pressure transducer system. Rigid gas permeable lenses were cleaned with one of two commercially available cleaners and then rinsed with one of five saline solutions or with tap water. High-resolution imaging was performed after each rinse, and light transmission through the lens surface was determined by measuring the mean pixel count within a 1 mm by 1 mm square.

RESULTS

The mean pixels/mm 2 and the rinsing method were correlated (Spearman rank order correlation, P <0.0001), that is, high pixel counts represented more lens surface deposits and residue, and as fluid pressure of the rinsing methods increased, mean pixels/mm 2 decreased.

CONCLUSIONS

Measured fluid pressure relates to lens surface opacity suggesting that some products leave less residue than others. In addition, tap water, with its high exiting fluid pressure, seems to be the most effective option for removal of RGP cleaners from the contact lens surface. Despite these findings, tap water rinse is not encouraged because of its potential to lead to corneal inflammation and infection; therefore, the development of alternative procedures and products is needed.

Contact Lens Safety for the Correction of Refractive Error in Healthy Eyes

ABSTRACT

Contact lenses are a safe and effective method for correction of refractive error and worn by an estimated 45 million Americans. Because of the widespread availability and commercial popularity of contact lenses, it is not well appreciated by the public that contact lenses are U.S. Food and Drug Administration (FDA)-regulated medical devices. Contact lenses are marketed in numerous hard and soft materials that have been improved over decades, worn in daily or extended wear, and replaced in range of schedules from daily to yearly or longer. Lens materials and wear and care regimens have impact on the risks of contact lens-related corneal inflammatory events and microbial keratitis. This article reviews contact lens safety, with specific focus on the correction of refractive error in healthy eyes.

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.

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.

Contact Lens Use Patterns, Behavior and Knowledge Among University Students in Thailand

Purpose

Little is known about contact lens (CL) use in young generation. This study aimed to investigate the patterns, behavior and knowledge of CL wear and care in Thai university students.

Methods

A cross-sectional study using online questionnaires was conducted during July 2019 to February 2020 in two Rajabhat universities, Bangkok, Thailand. Participant characteristics, CL information, knowledge and behaviors were collected. Factors associated with poor behaviors and CL-related corneal ulcers were analyzed using logistic regression.

Results

Of 493 students participating in the survey, 336 students (66.78%) were current CL users and completed the questionnaires. Mean age was 19.2 ± 1.4 years with female predominance (80.36%). All students wore soft CL with a major replacement schedule of monthly disposable (90.18%). Good CL wear and care behaviors were found in 190 students (56.55%). The most common poor CL behavior and poor CL knowledge were CL overuse (44.64%) and sleeping with lenses (31.85%), respectively. There were no correlations between behaviors and knowledge (r = 0.03). Purchasing lens from internet, wearing experience over one year, and long wear duration (> 12 hours) were significantly associated with poor CL behavior. Male gender and swimming with lens were significantly associated with history of corneal ulcers.

Conclusion

The study pointed out a low compliance of CL wear and care in Thai university students. Good CL practices, awareness of CL-related complications and purchasing place should be carefully informed and regularly stressed to minimize preventable visual damage in young population.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Gas-Permeable Contact Lenses and Water Exposure: Practices and Perceptions

SIGNIFICANCE

This study provides insight into the current recommendations, clinical behaviors, and risk assessments of eye care professionals on the topic of rigid contact lens exposure to tap water. This knowledge may motivate professional organizations to develop initiatives to educate eye care professionals on the dangers of contact lens exposure to water.

PURPOSE

The purpose of this study was to investigate the practice patterns and risk perceptions of eye care professionals regarding gas-permeable contact lens exposure to tap water.

METHODS

A branched-logic survey was started by 320 clinicians, vision scientists, and industry personnel and was fully completed by 272 participants. The survey queried participants about their current practices, recommendations, and perceptions of risk regarding exposure of gas-permeable contact lenses to tap water.

RESULTS

Of those who prescribe gas-permeable contact lenses, 57.4% reported rinsing lenses with tap water, whereas only 32.7% reported engaging in this same behavior in front of patients. Of those who reported never rinsing lenses with tap water, 85.6% indicated that rinsing lenses with water increases infection risk, whereas 52.1% of those who rinse lenses with water reported the same perceived risk (P < .001). Of all participants, 60% indicated that wearing contact lenses while showering increases infection risk, and 50.2% of all participants advised patients to avoid this behavior.

CONCLUSIONS

A discrepancy exists between perceptions of risk concerning exposure of contact lenses to water and both clinical practices and patient education provided by professionals.

Compliance behaviour change in contact lens wearers: a randomised controlled trial

BACKGROUND

Water exposure during contact lens wear has been associated with contact lens disease including microbial keratitis and sterile corneal infiltrates. Despite the documented risks, water exposure is common amongst lens wearers. This study aimed to determine the effect of water education in the form of "no-water" lens case stickers on water-contact behaviours and storage case contamination.

METHODS

In a prospective, masked, randomised controlled trial, 200 daily lens wearers were randomised to either receive a storage case with a "no-water" sticker (test) or without a "no-water" sticker (control). Both groups received written compliance information. Participants completed a self-administered lens hygiene questionnaire at baseline and after 6 weeks. Microbial analysis of used storage cases, collected at both study visits, was conducted using ATP and limulus amebocyte lysate (LAL) assays for overall microbial contamination and endotoxin levels, respectively. A one-way ANCOVA and multiple logistic regression determined the change in water-contact behaviours and storage case contamination over time.

RESULTS

A total of 188 lens wearers completed both study visits; 128 females and 60 males; average age 29 ± 13 (range 18-78 years); 95 test and 93 control participants. After 6 weeks, the overall water exposure score and endotoxin levels reduced significantly in the test group compared with the control group (p < 0.05). There were no significant changes in individual water-contact behaviours or overall storage case contamination.

CONCLUSION

A no-water infographic on the contact lens case improved overall water-contact behaviours and reduced storage case endotoxin. Refining the messaging may be beneficial in future to improve other aspects of compliance.

Water Exposure and the Risk of Contact Lens-Related Disease

PURPOSE

To describe the association of water exposure with contact lens (CL)-related disease and explore the guidelines regarding water exposure to CL wearers, provided by CL manufacturing industry, global public health, and CL-related professional associations.

METHODS

A review of the literature was conducted by searching PubMed, MEDLINE, and Web of Science databases up to September 2017 for articles published or translated in English using keywords: contact lens* AND tap water OR swimming OR showering OR water exposure AND microbial keratitis OR Acanthamoeba keratitis OR corneal infiltrate* OR ocular adverse event*. References in all relevant publications were also reviewed.

RESULTS

Water exposure during CL wear is associated with complications ranging from sterile corneal infiltrative events to sight-threatening infections. Despite the documented risks due to water exposure, water-related habits are common among CL wearers. This suggests a lack of awareness and understanding regarding the risks among CL wearers and potentially CL practitioners. Discrepancies exist in guidelines for CL hygiene and compliance provided by the CL manufacturing industry, global public health, and CL-related professional associations. There is also widespread use of water imagery within CL marketing and packaging materials. These factors may give rise to confusion among wearers and may contribute toward risk-taking behaviors.

CONCLUSIONS

Consensus among stakeholders about water and CL care is needed. Guidelines should unequivocally advocate for the avoidance of any water exposure including handling CLs with wet hands, rinsing CLs or storage cases in tap water, showering while wearing CLs and swimming with CLs without wearing goggles.

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.

Water Exposure is a Common Risk Behavior Among Soft and Gas-Permeable Contact Lens Wearers

PURPOSE

To understand soft contact lens (SCL) and gas-permeable (GP) lens wearers' behaviors and knowledge regarding exposure of lenses to water.

METHODS

The Contact Lens Risk Survey (CLRS) and health behavior questions were completed online by a convenience sample of 1056 SCL and 85 GP lens wearers aged 20 to 76 years. Participants were asked about exposing their lenses to water and their understanding of risks associated with these behaviors. Chi-square analyses examined relationships between patient behaviors and perceptions.

RESULTS

GP lens wearers were more likely than SCL wearers to ever rinse or store lenses in water (rinsing: 91% GP, 31% SCL, P < 0.001; storing: 33% GP, 15% SCL P < 0.001). Among SCL wearers, men were more likely to store (24% vs. 13%, P = 0.003) or rinse (41% vs. 29%, P = 0.012) their lenses in water. Showering while wearing lenses was more common in SCL wearers (86%) than GP lens wearers (67%) (P < 0.0001). Swimming while wearing lenses was reported by 62% of SCL wearers and 48% of GP lens wearers (P = 0.027). Wearers who rinsed (SCL; P < 0.0001, GP; P = 0.11) or stored lenses in water (SCL; P < 0.0001, GP P = 0.007) reported that this behavior had little or no effect on their infection risk, compared with those who did not. Both SCL (P < 0.0001) and GP lens wearers (P < 0.0001) perceived that distilled water was safer than tap water for storing or rinsing lenses.

CONCLUSIONS

Despite previously published evidence of Acanthamoeba keratitis' association with water exposure, most SCL, and nearly all GP lens wearers, regularly expose their lenses to water, with many unaware of the risk.

Molecular identification of waterborne free living amoebae (Acanthamoeba, Naegleria and Vermamoeba) isolated from municipal drinking water and environmental sources, Semnan province, north half of Iran

The present study tested 80 samples of municipal, geothermal and recreational water samples for the occurrence of waterborne free living amoebae (FLA) including Acanthamoeba, Balamuthia mandrillaris, Vahlkampfiids and Vermamoeba in Semnan province, North half of Iran. Four sets of primers including JDP1,2 primers, ITS1,2 primers (Vahlkampfiids), 16S rRNABal primers (Balamuthia mandrillaris) and NA1,2 primers (Vermamoeba) were used to confirm the morphological identification. From the 80 water samples tested in the present study, 16 (20%) were positive for the outgrowth of free living amoebae based on the morphological page key. Out of the 34 municipal water samples, 7 (20.6%) were positive for outgrowth of Free living amoeba, belonging to Vermamoeba, Naegleria and Acanthamoeba using molecular tools. Three out of the six investigated hot springs were also contaminated with Naegleria spp. Sequencing of the ITS1,2 region of the Vahlkampfiid isolates revealed the highest homology with N. gruberi (2 isolates), N. australiensis (1 isolate) and N. pagei (3 isolates). This is the first report of N. gruberi in the country. Using morphological and molecular analysis, Balamuthia mandrillaris was undetected in all the water samples. The present study further confirmed the occurrence of potentially pathogenic waterborne free living amoebae in habitats with high human activity. It is of utmost importance that more studies are conducted to evaluate the niches of B. mandrillaris and N. fowleri in Iran and worldwide. Such investigations regarding the relevance of FLA as a hazard to humans, should be brought to the notice of the health authorities.

Acanthamoeba Keratitis among Rigid Gas Permeable Contact Lens Wearers in the United States, 2005 through 2011

PURPOSE

To describe the clinical presentation and outcomes of Acanthamoeba keratitis (AK) in rigid gas permeable (RGP) contact lens wearers and to identify modifiable risk factors.

DESIGN

Case-control investigation.

PARTICIPANTS

Patients were RGP contact lens-wearing United States residents with a diagnosis of AK from 2005 through 2011. Controls were RGP contact lens wearers with no history of AK who were at least 12 years of age.

METHODS

Patients were identified during 2 multistate AK outbreak investigations. Controls from the first investigation in 2007 were identified using a reverse address directory. In the second investigation, controls were recruited from participating ophthalmology and optometry practices. Patients and controls were interviewed by phone using a standardized questionnaire. Odds ratios (ORs) and Fisher exact P values were calculated to assess risk factors associated with infection.

MAIN OUTCOME MEASURES

Acanthamoeba keratitis, a rare eye disease primarily affecting contact lens wearers, is caused by free-living amebae, Acanthamoeba species.

RESULTS

We identified 37 patients in the 2 investigations, 10 (27%) from the 2007 investigation and 27 (73%) from 2011. There were 17 healthy controls, 9 (53%) from 2007 and 8 (47%) from 2011. Among patients, 9 (24%) wore RGP lenses for orthokeratology or therapeutic indication; no controls wore RGP lenses for these indications. Significant risk factors for AK were wearing lenses for orthokeratology (OR, undefined; P = 0.02), sleeping while wearing lenses (OR, 8.00; P = 0.04), storing lenses in tap water (OR, 16.00; P = 0.001), and topping off contact lens solution in the case (OR, 4.80; P = 0.01). After stratifying by use of RGP lenses for orthokeratology, storing lenses in tap water and topping off remained significant exposures.

CONCLUSIONS

Nearly one quarter of patients were orthokeratology wearers. Using tap water to store RGP lenses and topping off solution in the lens case were modifiable risk behaviors identified in RGP wearers who wore lenses for both orthokeratology and nonorthokeratology indications. Rigid gas permeable wearers should avoid exposing their lenses to tap water and should empty their cases and use fresh lens solution each time they take out their lenses.

Acanthamoeba keratitis: improving the Scottish diagnostic service for the rapid molecular detection of Acanthamoeba species

Acanthamoeba species are responsible for causing the potentially sight-threatening condition, Acanthamoeba keratitis, which is commonly associated with contact lens use. In this report, we highlight the challenges faced using conventional laboratory identification methods to identify this often under-reported pathogen, and discuss the reasons for introducing the first national service in Scotland for the rapid and sensitive molecular identification of Acanthamoeba species. By comparing culture and molecular testing data from a total of 63 patients (n = 80 samples) throughout Scotland presenting with ocular eye disease, we describe the improvement in detection rates where an additional four positive cases were identified using a molecular assay versus culture. The testing of a further ten patients by confocal imaging is also presented. This report emphasizes the importance of continuing to improve clinical laboratory services to ensure a prompt, correct diagnosis and better prognosis, in addition to raising awareness of this potentially debilitating opportunistic pathogen.

Detection and Molecular Characterization of Potentially Pathogenic Free-living Amoebae from Water Sources in Kish Island, Southern Iran

Amoebic keratitis, a sight-threatening corneal infection, mainly occurs in contact lens wearers who wash their eyes with tap water. The present research was conducted to identify the occurrence of potentially pathogenic free-living amoebae (FLA) in tap water sources on Kish Island, a tourist region in Iran. Amoebae were detected using a culture-enriched method and by polymerase chain reaction (PCR)/sequencing of the diagnostic fragment 3 region of the 18S rRNA gene of Acanthamoeba. In the case of other free-living amoebae species, PCR/sequencing analysis of the 18S rDNA was conducted. Results of this study showed the presence of Acanthamoeba belonging to T3, T4, T5, and T11 genotypes in tap water sources. Additionally, Vermamoebae vermiformis was detected in three water samples. This is the first report of the Acanthamoeba genotypes T3, T4, T5, and T11 and V. vermiformis species in tap water sources in a tourist region in Iran.

[Evaluation of in vitro efficacy of combined riboflavin and ultraviolet-A (365 nm) for Acanthamoeba]

INTRODUCTION

Acanthamoeba keratitis is a rare but serious disease and is particularly difficult to treat when the diagnosis is delayed, partly because of the limitations of current therapies. The purpose of our study is to evaluate the anti-amoebic effectiveness of riboflavin and UV-A on Acanthamoeba castellani.

MATERIALS AND METHODS

We tested the effect of 0.02% chlorhexidine alone (C), the combination of riboflavin 1% and UV-A (UV-A+R), and the combination of the two treatments (R+C+UV-A) on cultures of vegetative and cystic forms of A. castellani. We conducted a parasite count under optical microscopy for each treated area at day 1, 4 and 8.

RESULTS

There was a decrease in the number of cysts for all three treatments (C, UV-A+R, R+C+UV-A). This reduction was greater for the plates treated with R+UV-A (P <0.01 at D8) and those treated with C+R+UV-A (P<0.001 at D8) compared to those exposed to chlorhexidine alone (C). There was no decrease in the number of amoebic trophozoites for the three treatments (C, UV-A+R, R+C+UV-A), but encystment was observed.

DISCUSSION

Given the in vitro efficacy of riboflavin combined with UV-A against cystic forms of A. castellani and excellent in vivo tolerance of the procedure, the treatment of acanthamoeba keratitis might be improved by this new therapeutic approach.