The significance of hand wash compliance on the transfer of dermal lipids in contact lens wear

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.

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 the factors which impact overall satisfaction with single vision contact lenses

PURPOSE

To explore the impact of subjective factors (lens handling, comfort and vision) on overall single vision contact lens satisfaction.

METHODS

Correlation analysis of a prospective, randomised, double-masked, bilateral crossover study involving 55 adapted lens wearers fitted with somofilcon A (SiHy) (clariti® 1 day, CooperVision) and etafilcon A (Hy) (1 DAY ACUVUE® MOIST, Johnson & Johnson Vision) was conducted. Subjective ratings of lens handling, comfort and vision collected after 1 week of lens wear for each lens type were correlated with overall satisfaction. Data were analysed by combining data for both lens types and also for each lens separately.

RESULTS

For the combined analysis, significant correlations (p < 0.01) were found between subjective ratings of overall satisfaction and ratings of handing for application (r = 0.64), handling for removal (r = 0.50), comfort upon application (r = 0.59), comfort at end of day (r = 0.61), overall satisfaction with comfort (r = 0.88) and overall satisfaction with vision (r = 0.64). Correlation analysis of the per lens data showed that lens specific correlations of overall satisfaction with handling for lens application varied greatly with lens material (SiHy: r = 0.26, p = 0.05 vs Hy: r = 0.72, p < 0.01). Correlation strength of comfort upon application/at end of day with overall satisfaction also varied with lens material (Application: SiHy: r = 0.40 vs Hy: r = 0.61; End of day: SiHy: r = 0.76 vs Hy: r = 0.58; all p ≤ 0.01).

CONCLUSION

Overall satisfaction was significantly correlated with the specific subjective evaluations of handling, vision and comfort. Correlations of overall satisfaction and ease of handling for each lens type suggest that, for habitual contact lens wearers, dissatisfaction with handling at the time of lens application can play a major role in overall dissatisfaction with a lens. Handling for application had a similar correlation (r) value as vision, suggesting that handling for application should not be underestimated when considering overall patient satisfaction.

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.

Fungal isolation from disinfectant solutions of contact lens storage cases among asymptomatic users

OBJECTIVES

To investigate the incidence of fungal contamination of store disinfectant solutions contained in contact lens storage cases belonging to asymptomatic contact lens users.

METHODS

Asymptomatic contact lens users were asked to bring their storage cases, lenses included, without having opened the lid of the cup after placing lenses inside. The following information was recorded: age, sex, type of refractive error, contact lens material, schedule of wear, and brand of disinfectant solution. Included subjects had to comply with lens handling, cleaning, and replacement instructions given by the manufacturer or their attending optometrist. One sample per cup of contact lens case was collected using a sterile syringe. Samples were cultured on proper media for 96 hr at 35°C. Fungi were identified to species level by standard methodology.

RESULTS

A total of 216 samples were collected from 117 contact lens storage cases. All participants were using monthly disposable hydrogel lenses on a daily wear basis. Seven fungal species were isolated from 15 specimens (6.9%) collected from 12 storage cases (10.2%). These included one Fusarium solani, four Aspergillus niger, two Aspergillus fumigatus, five Candida parapsilosis, one Candida tropicalis, one Rhodotorula rubra, and one F. solani in combination with Candida guilliermondii. Disinfectant solutions containing hydrogen peroxide were found to be less effective than various alternative solutions in eliminating fungal species.

CONCLUSIONS

The results of this study show that even when contact lens users report compliance for handling, cleaning, and replacement according to the manufacturer's instructions, the potential risk of contact lens-related fungal keratitis still remains.