Literature review
Section 1: Background
Context and rationale for research priorities
Lens handling intensifies the incidence of lens contamination. When lens are aseptically removed from the eye, they still have a high probability of harboring microorganisms. During storage, the frequency of positive microbial bioburden remains high than 50%. The presence or movement of microorganisms from the lens to the ocular surface is a route factor for contact lenses related microbial keratitis and inflammation. There is need to priotise research in this area because the results of the studies help people to understand the factors concomitant to infectious and inflammatory complications. When strategies to avert bacterial colonization is introduced, it will be possible to reduce the occurrence of microbially driven contact lens complications. The use of soft contact lenses is increasing at an alarming rate, and this increases the probability of induced infection of the contact lenses. It is, therefore, important to lens wearers to remain cautious and take the necessary measures for practicing proper hygiene standards to avoid befalling victims of microbial infections.
The storage case contamination of contact lenses is affected by various factors, and this includes the disinfecting solution type, storage case material, and case storage design, age of the lens case, CL wear schedule, and compliance with disinfection amongst others (Vijay, 2015, p. 96). Even though the link between the CL storage case age and contamination has not yet been proven, the current recommendation is to substitute it in every three months despite reports indicating that the storage case is already contaminated between two and four weeks of usage (ibid).
SECTION II and III: Understanding and discussion of relevant examples of published work and an overview of methodological approaches used in the studies.
Wu et.al (2010) conducted a quantitative study to examine the profile and frequency of microbial contamination of contact lens cases (p. 152). In the study, the researchers aimed at assessing the frequency and profile of contact lens storage case contamination to the asymptomatic contact lens wearers. Furthermore, they wanted to evaluate if the different areas of the same lens may indicate a different rate and profile of contamination. Nonetheless, the association between lens storage case information and the age of the lens storage case was also investigated (Wu et.al, 2010, p. 155). The sample size of the study comprised of 64 lens cases case age information that was gathered from asymptomatic contact lens wearers. In addition, these samples were put under microbial investigation so as to recover of bacteria and fungi. An analysis was conducted to identify the presence of contamination rate between the two sampling locations and the correlation between contamination levels and age of the lens (Wu et.al, 2010, p.157).
The results of the study illustrated that contamination took place in 58 (37 of 64) of the lens cases. According to Wu et.al (2010), the most repeatedly recuperated microorganisms comprised of coagulase-negative Staphylococci (51%, 19 of 37), Bacillus spp. (43%, 16 of 37), and fungi (27%, 10 of 37) (p.156).Besides, the flat-well lens cases depicted that a high number of the microorganisms were convalesced from the upper rim compared to that of the lower base (p_0.02), while at the same time, in the upper rim, it was the grander variety of Gram-negative bacteria that was recovered. The results and findings of the study indicated that the recurrent replacement of the lens may result in a reduction of the microbial contamination. Moreover, the future studies should illustrate the particular points swabbed in the lens case. Wu et.al, 2010 recommended the need to introduce and lessen contamination of the risky areas of the lens to establish an improved storage lens case design (p.158).
In another study, Wu et.al (2011) investigated the impact of lens case hygiene guidelines on contact lens case contamination (p.1180). In the study, the lens case contamination was used as a risk factor for microbial keratitis. The researchers pinpointed that in the past, there have been no evaluations indicating the effectiveness of manufacturers’ lens case guidelines in restraining microbial contamination. Therefore, the study did a comparison of the effectiveness of manufacturers’ guidelines and an alternative cleaning regimen. Wu et.al (2011, p.1181) applied a randomized cross-over clinical trial with two phases. The participants of the study were allowed to use their preferred lenses with a combination of a multipurpose solution for daily wear. The results of the study illustrated that the case contamination rate stood at 82% in the group with the guidelines from the manufacturers while the alternative regimen group recorded a contamination rate of 72%. It was concluded that alternative guidelines ate more efficacious in eradicating the microbial contamination of the lens cases compared to the efficiency of the current manufacturer’s guideline. In other terms, integrating the rubbing and tissue-wiping steps on a daily case hygiene lessens viable organism contamination.
The results matched with the previous vitro findings that illustrated that the alternative guidelines had a reduced level of microbial contamination in comparison to the manufacturer’s guidelines (Wu et.al, 2011, p. 1185). While the study emphasized at comparing the effectiveness of two lens case cleaning guidelines, the contact lens was critically cleaned various strategies like take-home instructions sheets, researcher’s demonstrations, and instruction stickers on solution bottles. The alternative guidelines proved to be more efficient because of the additional cleaning steps that included rubbing and tissue-wiping. The compliance levels between the two groups were the same (ibid). The results of Wu et.al (2011, p.1187) study should be of benefit to practitioners as it allows them to provide evidence-based advice on how to clean contact lens cases to lower the incidence of contact lens-related inflammatory infections.
Wu, Willicox, and Stapleton (2015) conducted a qualitative study to investigate the effect of contact lens hygiene behavior on lens case contamination (p.167). In the study, the researchers conducted a survey to capture vital information for contact lens wearers, and this included wearer demographics and their contact lens hygiene behavior. Besides, the microbial analysis of lens cases was conducted. Multivariate analysis identified the factors linked to the contamination of contact lens storage. The results of the study in the multivariate analysis indicated that cleaning hands using soap detergents and water had a lower case of lens case contamination compared to just water or no washing. The wet lens cases had a higher probability of contamination compared to the dry lens. The risk factor for lens case contamination was mismatching lens case and disinfecting solution. Wu, Willicox, and Stapleton (2015) concluded that “washing hands with soap and water, air-drying lens cases, and matching of the disinfecting solution with lens case was a major factor that reduced lens case contamination” (p.174). The results can be beneficial in a clinical set-up as it can be used to offer advice to lens wearers.
Hickson-Curran (2010) conducted a study on the important aspects of the contact lens adherence and to analyze the contact replacement survey frequency that are the crucial guidelines for the procedure of care and cleanliness of the lens storage case (p.208).
The sample size of the research study was composed of 645 contact lens audiences whose ages range were between 12-39 years. These respondents in the study included those wearing prescription contact lenses and replacement lenses. The audiences of the study were not notified of the aims of the research study (Hickson-Curran, 2010, p.210).
The outcomes of the research study indicated that the weekly replacement of the research study was more compared to the monthly replacement of the contact lens audiences. According to Hickson-Curran (2010), the weekly replacement comprised 45% within two weeks, 68% within three weeks, and 89% within four weeks. On the monthly replacement, the contact replacement for four weeks were 37%, five weeks were 57%, and 23 % were more than eight weeks. The results imply that the median frequency for disinfecting lens storage case was 2-3 times per week and 33% for disinfecting for at most one month. Moreover, the findings of the study indicated that the majority of the patients cleaned their lenses with hot or cold water (p.212).Hickson-Curran (2010), recommends that the eye cares medical personnel should develop measures that stress the need to adopt best practices with relation to lens replacement (p.214).
Dutot (2009) seeks to research whether the multipurpose solutions applied in contact lens disinfections could have the same traces of background of ocular pathologies. Furthermore, the scholars wanted to understand the ocular tolerance of the contact lens rules on a human conjunctival cell line whose reaction to preservatives had been justified. The main purpose of this research study was to examine the percentage of contact lens wearers and the lens care regime in a specified number of patients who had serious ocular infections that were immunized with pharmacy-manufactured fortified antibiotic eye drops. For the research study to be possible, they assumed that the contact lens multipurpose solutions were not contaminating products but the preservatives in question. The serious ocular infection was due to limited disinfection efficacy. Additionally, the research study viewed that multiple care solutions occurred in the presence of contact lens by p2X7 receptor activation (Dutot, 2009, p.471).
Dutot (2009) perceives that the research study encompassed 91 adults that were suffering from severe ocular infections. The Patients were offered a questionnaire to examine the background of their severe ocular infection and autecology. The observational study was conducted to trace the approximate number of contact lens audiences, the form of contamination and the kinds of lens regimes. The study was evaluated to trace the multipurpose solutions that were evaluated on a certain cell with the application of a cytofluorometry (p.471).
The results of the study highlighted that 80% of the total populace applied multipurpose solutions. According to Dutot (2009), 59% of the contact lens audiences consumed multipurpose solutions while the 35% consumed oxidative products. The results showed that the multipurpose solutions were not more effective compared to the microorganisms and therefore can only be viewed as a preservative rather than a disinfectant. From the findings, the cytofluorometry study gave a platform for the audiences to showcase that the contact cases multipurpose solutions contained preservatives that were doomed cytotoxic in nature.
Dutot (2009) recommends that the international health standards in relation to cytotoxicity and disinfection of multipurpose solutions should be reviewed once more to ensure that the available molecules are effective against the bacteria.
Vijay (2015, p. 91) postulates that the instances of continuous contact lens microbial contamination is frequent and is linked with sterile corneal infiltrates and microbial keratitis. The research study wanted to comprehend the capability of numerous present storage case cleaning tactics in the manifestation and nonexistence of disinfectants to coax out large microbial biofilms (Vijay, 2015, p.91). The study involved the study on the two ocular constraints of P. aeruginosa and S. aureus to form robust biofilms. The usefulness of removing the biofilm under the elements such as hot water were done (ibid).
The sample size of the research study included the test storage cases that were vaccinated with 2ml of 10 colonyforming units per ml of ocular isolates of pseudominas aeruginosa and stored for one day. Furthermore, the cases were immunized in numerous ways that signified current practice that composed of a 10-s rinse containing PMHB and polyquaternium that were preceded by air dying for a quarter of a day period. The assessment was performed using standard culture techniques to estimate the number of survivors.
The results of the study showed that the most applicable storage case hygiene regimes were not enough to remove enormous biofilms. Vijay (2015) postulates that the challenge biofilms comprised of 8.460.1 log CFU (P. aeruginosa) and 7.160.2 log CFU (p.95). Nonetheless, the rinsing with MPS and air drying had less impact on S. aureus biofilms, and the outcome was the exclusion of P. aeruginosa. The results and findings of the study highlighted that rinsing with MPS or tissue wiping led to the highest reduction in the biofilm. The specific level of reduction was 0.960.2 log CFU survivors of P. aeruginosa and 3.461.2 log CFU of S. aureus. Nevertheless, Vijal views that advanced research should suggest that the present industrialists’ recommendations necessitate some modification for hindering the persistent contamination of the storage cases (Vijay, 2015, p.95).
Bibliography
Dutot, M., Paillet, H., Chaumeil, C., Warnet, J.M. and Rat, P., 2009. Severe ocular infections with contact lens: role of multipurpose solutions. Eye, 23(2), pp.470-476.
Hickson-Curran, S., Chalmers, R.L. and Riley, C., 2011. Patient attitudes and behavior regarding hygiene and replacement of soft contact lenses and storage cases. Contact Lens and Anterior Eye, 34(5), pp.207-215.
Vijay, A.K., Willcox, M., Zhu, H. and Stapleton, F., 2015. Contact lens storage case hygiene practice and storage case contamination. Eye & contact lens, 41(2), pp.91-97.
Wu, Y.T., Teng, Y.J., Nicholas, M., Harmis, N., Zhu, H., Willcox, M.D. and Stapleton, F., 2011. Impact of lens case hygiene guidelines on contact lens case contamination. Optometry & Vision Science, 88(10), pp.E1180-E1187.
Wu, Y.T., Willcox, M.D. and Stapleton, F., 2015. The effect of contact lens hygiene behavior on lens case contamination. Optometry & Vision Science, 92(2), pp.167-174.
Wu, Y.T., Zhu, H., Harmis, N.Y., Iskandar, S.Y., Willcox, M. and Stapleton, F., 2010. Profile and frequency of microbial contamination of contact lens cases. Optometry & Vision Science, 87(3), pp.E152-E158.
