Multipurpose Solutions Research Articles

Biofilm modelling on the contact lenses and comparison of the in vitro activities of multipurpose lens solutions and antibiotics.

During the contact lens (CL) usage, microbial adhesion and biofilm formation are crucial threats for eye health due to the development of mature biofilms on CL surfaces associated with serious eye infections such as keratitis. For CL related eye infections, multi drug resistant Pseudomonas aeruginosa or Staphylococcus aureus (especially MRSA) and Candida albicans are the most common infectious bacteria and yeast, respectively. In this study, CL biofilm models were created by comparing them to reveal the differences on specific conditions. Then the anti-biofilm activities of some commercially available multipurpose CL solutions (MPSs) and antibiotic eye drops against mature biofilms of S. aureus, P. aeruginosa, and C. albicans standard and clinical strains were determined by the time killing curve (TKC) method at 6, 24 and 48 h. According to the biofilm formation models, the optimal biofilms occurred in a mixture of bovine serum albumin (20% v/v) and lysozyme (2 g/L) diluted in PBS at 37 °C for 24 h, without shaking. When we compared the CL types under the same conditions, the strongest biofilms according to their cell density, were formed on Pure Vision ≥ Softens 38 > Acuve 2 ∼ Softens Toric CLs. When we compared the used CLs with the new ones, a significant increase at the density of biofilms on the used CLs was observed. The most active MPS against P. aeruginosa and S. aureus biofilms at 24 h was Opti-Free followed by Bio-True and Renu according to the TKC analyses. In addition, the most active MPS against C. albicans was Renu followed by Opti-Free and Bio-True at 48 h. None of the MPSs showed 3 Log bactericidal/fungicidal activity, except for Opti-Free against S. aureus and P. aeruginosa biofilms during 6 h contact time. Moreover, all studied antibiotic eye drops were active against S. aureus and P. aeruginosa biofilms on CLs at 6 h and 24 h either directly or as 1/10 concentration, respectively. According to the results of the study, anti-biofilm activities of MPSs have changed depending on the chemical ingredients and contact times of MPSs, the type of infectious agent, and especially the CL type and usage time.

Uptake and Release of a Multipurpose Solution Biocide (MAP-D) From Hydrogel and Silicone Hydrogel Contact Lenses Using a Radiolabel Methodology.

The purpose of this study was to evaluate the uptake and release of radiolabelled myristamidopropyl dimethylamine (MAP-D) on reusable daily wear contact lenses (CLs) over 7 days. Three silicone hydrogel (SH) CL materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were tested. A short-term (experiment 1, N=4) and a longer-term (experiment 2, N=3) study was conducted. In experiment 1, the CLs were incubated in 2 mL of phosphate buffered solution (PBS) containing 14C MAP-D (5 μg/mL) for 8 hrs. The release of 14C MAP-D was measured at t=0.25, 0.5, 1, 2, 4, 8, and 24 hr in PBS. In experiment 2, the CLs were incubated in the 14C MAP-D solution for 8 hrs followed by a 16-hr release in PBS. This cycle was repeated daily for 7 days. At the end of both experiments, lenses were extracted to determine the total uptake of MAP-D. The radioactivity was measured using a beta scintillation counter. In experiment 1, all three SH lenses sorbed similar amounts of MAP-D (P=0.99), all of which were higher than the two CH materials (P<0.01). However, the CH materials released a greater amount of MAP-D than the SH materials (P<0.01). In experiment 2, the uptake of MAP-D in SH materials increased over 7 days, whereas the amount of MAP-D remained constant in the CH materials (P=0.99). Similar to experiment 1, the CH lenses released more MAP-D than SH lenses after 7 days (P<0.01). The SH materials absorbed greater amounts of MAP-D compared to CH materials. However, the CH materials released the greatest amount of MAP-D. Radioactive labelling of MAP-D offers a highly sensitive method of assessing the uptake and release profiles of biocides to CL materials.

Impact of a low molecular weight hyaluronic acid derivative on contact lens wettability

PurposeTo investigate the interaction of a novel low molecular weight hyaluronic acid derivative containing hydrophobic groups with soft contact lenses and its effect on lens hydrophilicity compared with a conventional form of hyaluronic acid. MethodsThis investigation studied the uptake of fluorescently-labelled hyaluronic acid and a low molecular weight hyaluronic acid derivative to four types of contact lenses using fluorescent microscopy and confocal laser scanning microscopy. Further, the four lens types were used to compare efficacy in improving hydrophilicity, as well as maintenance of contact angle measurements, in commercially available multipurpose solutions that contained either hyaluronic acid, the low molecular weight hyaluronic acid derivative, or an alternative wetting agent. ResultsThe low molecular weight hyaluronic acid derivative was found to sorb more readily to silicone hydrogel lenses and exhibit a greater accumulation over time than conventional hyaluronic acid. Multipurpose solutions containing the low molecular weight hyaluronic acid derivative showed an increase in lens hydrophilicity through decreases in contact angle measurements when compared with those obtained from lenses treated with multipurpose solutions containing conventional hyaluronic acid or alternative wetting agents. This increase in lens hydrophilicity associated with the low molecular weight hyaluronic acid derivative was also maintained over multiple cycles in phosphate buffered saline, while alternative solutions with conventional hyaluronic acid did not. ConclusionOverall, lens treatment using a low molecular weight hyaluronic acid derivative-based solution lead to improved in vitro lens hydrophilicity.

Green Infrastructures for Urban Water System: Balance between Cities and Nature

Urban water systems face severe challenges such as urbanisation, population growth and climate change. Traditional technical solutions, i.e., pipe-based, grey infrastructure, have a single purpose and are proven to be unsustainable compared to multi-purpose nature-based solutions. Green Infrastructure encompasses on-site stormwater management practices, which, in contrast to the centralised grey infrastructure, are often decentralised. Technologies such as green roofs, walls, trees, infiltration trenches, wetlands, rainwater harvesting and permeable pavements exhibit multi-functionality. They are capable of reducing stormwater runoff, retaining stormwater in the landscape, preserving the natural water balance, enhancing local climate resilience and also delivering ecological, social and community services. Creating multi-functional, multiple-benefit systems, however, also warrants multidisciplinary approaches involving landscape architects, urban planners, engineers and more to successfully create a balance between cities and nature. This Special Issue aims to bridge this multidisciplinary research gap by collecting recent challenges and opportunities from on-site systems up to the watershed scale.

A polymer-based technique to remove pollutants from soft contact lenses

PurposeTo demonstrate an alternative to the rinse and rub (RR) method for cleaning pollutants from the exterior surface of soft contact lenses. This proposed technique is termed Polymer on Polymer Pollutant Removal (PoPPR), which utilizes the elastic properties of polydimethylsiloxane (PDMS) to physically remove contaminants from contact lens surfaces through non-adhesive unpeeling. MethodsThree different ratios of setting agent to polymer PDMS (1:30, 1:40, and 1:50) were evaluated using the PoPPR method against the control method of RR with a commercial multi-purpose lens cleaning solution. Three simulated pollutants of different sizes: pollen (25−40 μm), microbeads (1−5 μm), and nanoparticles (5−10 nm), were used to test the effectiveness of both cleaning methods. The fraction of pollutants removed from each contact lens was recorded and evaluated for significance. ResultsPDMS 1:40 was found to be the optimal ratio for lens cleaning using the PoPPR method. For larger particles (>10 μm), no difference was observed between conventional RR and proposed PoPPR method (p > 0.05). However, the new PoPPR technique was significantly better at removing small PM2.5 particles (<2.5 μm) compared to the RR method, specifically for microbeads (p = 0.006) and nanoparticles (p < 0.001). ConclusionThis proof-of-concept work demonstrates that the PoPPR method of cleaning contact lenses is as effective as the conventional cleaning method for larger particles such as pollen. The PoPPR method is more effective at removing extremely fine particulate pollutants, including microplastics and nanoparticles. This method offers a potentially more efficient cleaning protocol that could enhance the safety, health, and comfort of contact lens users, especially those living in regions with significant air pollution.

Benchmarking evaluation of five PHMB-based multi-purpose solutions and a silicone hydrogel contact lens

AIM: To evaluate and compare the clinical performance of 5 kinds of polyhexamethylene biguanide (PHMB) based multi-purpose solutions (MPS) manufactured in China when used with a commercially available silicone hydrogel contact lens in terms of solution-induced corneal staining (SICS), ocular response (corneal staining and ocular hyperemia), corneal infiltrative event (CIEs) and ocular comfort. METHODS: This was a prospective, open label, randomized, parallel group clinical trial. Totally 162 participants (Pxs) who were at least 18y were enrolled and randomized into 5 groups of PHMB-based MPS made in China: Complete® MPS, Hydron® Aqua-shining moist, Baoshining™, Weicon® Fresh, Weicon® 2000 MPS (abbreviated as C, H, B, W, and W2). All participants wore balafilcon A contact lenses with monthly disposal (Bausch &amp; Lomb Purevision®) in conjunction with the designated MPS on a daily wear for 3mo. Clinical visits were at baseline, 2wk, 1mo and 3mo. SICS and CIE were reported as first event incidence per 100 Px-months. Ocular response was graded on 0-4 scale in 0.5 steps (0=none, 4=severe) and ocular comfort was assessed via a numeric rating scale (1-10 in 1-point steps, 1=poor, 10=excellent). Ocular comfort and ocular response variables were analysed using linear mixed model. CIE and SICS were analysed using Fisher’s exact test and logistic regression. RESULTS: There were 36 (22%) Pxs who dropped out. SICS incidence for each MPS were: H (26.3%), B (20.8%), W (19.4%), W2 (13.4%), C (12.8%). The SICS rate of H was significantly different to W2 (P=0.012) and C (P=0.005). There were no significant differences in ocular response, CIE incidence and ocular comfort between different MPSs (P&gt;0.05). Pxs with SICS had significantly lower comfort during the day and at the end of than those who did not have SICS. CONCLUSION: Differences in SICS incidence are found between MPSs but not for CIE incidence, ocular response or ocular comfort. SICS in PHMB-based MPS is found to be associated with ocular discomfort. More MPS/lens combinations should be studied in the future.

Short and medium- to long-term impacts of nature-based solutions on urban heat

Many cities are growing and becoming more densely populated, resulting in land use changes, which promotes an increase in urban heating. Nature-based solutions (NBS) are considered sustainable, cost-effective and multi-purpose solutions for these problems. While various studies assess the effects of NBS on urban heat or urban sprawl/compaction, no studies assess their cumulative effect. The main objective of this study is to assess the short-term and medium- to long-term impacts of NBS on urban heat fluxes, taking as a case study the city of Eindhoven in The Netherlands. An integrated modelling approach, composed of a coupled meteorological and urban energy balance model (WRF-SUEWS) and an hedonic pricing simulation model (SULD), is used to assess urban heat fluxes and urban compaction effects, respectively. Results show that, in the short-term, NBS have a local cooling effect due to an increase in green/blue spaces and, in the medium to long-term, an urban compaction effect due to attraction of residents from peripheral areas to areas surrounding attractive NBS. This study provides evidence that NBS can be used to reduce the effects of urban heating and urban sprawl and that an integrated modelling approach allows to better understand its overalleffects.

Assessment of a Multipurpose Solution by Video Gamers and Non-gamers

Purpose: Video gaming is popular worldwide, and its benefits and risks have come to the attention of health care providers across disciplines. Blink rate, blink amplitude, and tear film stability are compromised during dynamic, prolonged use of digital devices, which can result in symptoms of discomfort with contact lens wear. In addition to lens material and design, the choice of lens care cleaning and disinfecting solution can affect wearer satisfaction. The purpose of this evaluation was to compare real world experiences with a hyaluronan-containing contact lens multipurpose solution (MPS) among subjects classified as video gamers and non-gamers. Methods: This study was a prospective, single arm, open label survey of contact lens wearers who used a computer, smartphone, or tablet for a minimum of three hours daily. Contact lens-wearing gamers (subjects who reported that they play electronic games while wearing contact lenses 2-hours or more daily) and non-gamers were provided Biotrue MPS to use for at least seven-days while wearing a fresh pair of their respective habitual contact lenses. Subjects rated performance attributes via an online survey using a 6-point Likert scale. Results: At baseline, gamers were younger than non-gamers, more likely male, spent more time using digital devices daily, and were more likely to report they suffer from eyestrain, sensitive eyes, and red eyes. Both groups rated all queried lens-wearing performance attributes positively; gamers gave higher mean ratings than did non-gamers to 23 of 24 queried attributes, including all four pertaining to long durations of digital device use. After adjusting for both age and gender, significant differences favoring gamers were noted for all 24 attributes. Conclusions: Contact lens wearing gamers and non-gamers rated Biotrue MPS highly based upon various performance attributes. Biotrue MPS remains a good choice for general lens wear, as well as during tear film-challenging video game play.

Anti-Acanthamoeba effect of potassium isostearate for use as a multipurpose solution.

Acanthamoeba is one of the organisms that cause corneal infection. In this study, attention was focused on potassium isostearate (iso-C18K, a branched chain fatty acid salt) for use in a multipurpose solution (MPS) against Acanthamoeba. An anti-amoebic test against Acanthamoeba castellanii ATCC 30010 (trophozoites type) was conducted. As a result, a growth reduction effect of 4 log units (99.99% suppression) was observed after incubation with 150 mM (5.0 w/v%) iso-C18K for 10 minutes. Furthermore, after the amoeba suspension was mixed with iso-C18K, disruption of cell membranes were observed, and the minimum amoebacidal concentration (MAC) at that time was 9.6 mM (0.31 w/v%). To evaluate the effectiveness as an MPS, assessment by verification tests was conducted using contact lenses. Reducing the concentration of iso-C18K caused a decrease in the number of viable cells, which was confirmed at a MAC of 1.2 mM (0.039 w/v%).

Effect of multipurpose care solutions upon physical dimensions of silicone hydrogel contact lenses.

Interactions between contact lens multipurpose solution (MPS) components and the contact lenses with which they are used are both lens and solution dependent. As such, lens dimensional changes may arise after cleaning and immersion cycling in different lens care solutions over different time courses. In this study, the dimensional stability of five planned-replacement silicone hydrogel lenses (lotrafilcon B, comfilcon A, senofilcon A, senofilcon C, and samfilcon A) over 30 cycles in three different MPSs (Biotrue, OPTI-FREE Express, and OPTI-FREE Puremoist) was evaluated. Measurements of diameter, sagittal depth, power, roundness, and center thickness were obtained prior to, during, and after 30 cycles of cleaning and storage. Diameters of all lenses increased when soaked in Express or Biotrue but held the International Standards Organization (ISO) tolerance over the full course of 30 disinfection cycles; however, the diameters of comfilcon A, senofilcon A, senofilcon C, and samfilcon A lenses soaked in Puremoist exceeded ISO tolerance after between 4 and 9 immersion cycles. In contrast, the diameter of lotrafilcon B held tolerance. Similarly, all lenses cycled in Express or Biotrue held tolerance for sagittal depth, while in Puremoist only lotrafilcon B held tolerance. All lenses became less round in all MPSs but held tolerance for both power and central thickness. Given the lack of reported clinical issues with Puremoist when used with lenses other than lotrafilcon B, we propose that it may be appropriate to revisit the ISO test methods and tolerances to determine if they are still applicable for silicone hydrogel lenses.

Prevention of Pseudomonas aeruginosa Biofilm Formation on Soft Contact Lenses by Allium sativum Fermented Extract (BGE) and Cannabinol Oil Extract (CBD).

Two natural mixtures, Allium sativum fermented extract (BGE) and cannabinol oil extract (CBD), were assessed for their ability to inhibit and remove Pseudomonas aeruginosa biofilms on soft contact lenses in comparison to a multipurpose Soft Contact Lens-care solution present on the Italian market. Pseudomonas aeruginosa (ATCC 9027 strain) and Pseudomonas aeruginosa clinical strains isolated from ocular swabs were tested. Quantification of the biofilm was done using the microtiter plate assay and the fractional inhibitory concentration index was calculated. Both forms of Pseudomonas aeruginosa generated biofilms. BGE at minimal inhibitory concentration (MIC) showed inhibition percentages higher than 55% for both strains, and CBD inhibited biofilm formation by about 70%. The care solution at MIC inhibited biofilm formation by about 50% for both strains tested. The effect of BGE on the eradication of the microbial biofilm on soft contact lenses at MIC was 45% eradication for P. aeruginosa ATCC 9027 and 36% for P. aeruginosa clinical strain. For CBD, we observed 24% biofilm eradication for both strains. For the care solution, the eradication MICs were 43% eradication for P. aeruginosa ATCC 9027 and 41% for P. aeruginosa clinical strain. It was observed that both the test soft contact lenses solution/BGE (fractional inhibitory concentration index: 0.450) and the test soft contact lenses solution/CBD (fractional inhibitory concentration index: 0.153) combinations exhibited synergistic antibiofilm activity against most of the studied bacteria. The study showed that BGE and CBD have good effect on inhibition of biofilm formation and removal of preformed biofilms, which makes them promising agents that could be exploited to develop more effective care solutions.

Main principles of choice of multi-purpose design solutions for construction operations when conducting judicial construction and technical expertise (JCTE)

The article contains the discussion of materials on the principles of selection of multi-purpose design solutions for the construction industry when conducting a judicial construction and technical expertise, as well as the presentation and an algorithm for solving problems of this type. Based on the interpretation of results of theoretical works and analysis of judicial practice, a method was obtained that can be used when conducting a judicial construction and technical expertise in order to solve the issues of selecting design solutions and materials. When using this method, all rearrangements of variants are checked by their preference and compared with each other. The considered method has been continually applied in solving practical issues of judicial construction and technical expertise. Actually, this type of tasks is often found in the framework of arbitration processes when solving issues on the effectiveness of the use of budgetary funds. The use of the proposed algorithm is the most optimal for the preparation of conclusions of a forensic construction expert for cases of this category.

Comparison of a povidone-iodine containing multi-purpose solution with other MPS for rigid lenses against bacterial biofilm

To assess the contribution and safety of bronchoscopic cryobiopsy vs traditional forceps biopsy used in clinical practice for diagnosing diffuse parenchymal lung disease (DPLD).We identified 271 patients who underwent bronchoscopic biopsy for DPLD at Mayo Clinic, MN (June 1, 2013, through September 30, 2017). Medical records were reviewed including prebiopsy clinical and radiographic impressions. Diagnostic yield was assessed in terms of a specific histologic pattern resulting in a diagnosis when combined with the clinical-radiologic context. Clinical utility was defined as a biopsy result deemed useful in patient management.The cohort included 120 cryobiopsy and 151 forceps biopsy cases with mean age 61±14 years and 143 (53%) men. Diagnostic yield (55% vs 41%; odds ratio [OR], 1.73; 95% CI, 1.07 to 2.83; P=.026) and clinical utility (60% vs 40%; OR, 2.21; 95% CI, 1.36 to 3.63; P=.001) were higher for the cryobiopsy group, and the association remained after control for prebiopsy clinical impressions (OR, 2.21; 95% CI, 1.22 to 4.08; P=.010 and OR, 3.23; 95% CI, 1.76 to 6.10; P<.001, respectively). However, pneumothorax (5.4% vs 0.7%; P=.022) and serious bleeding (7.1% vs 0%; P=.001) rates were higher for the cryobiopsy group. Thirty-day mortality was 1.6% in the cryobiopsy group vs 0% for the forceps biopsy group (P=.20).Bronchoscopic cryobiopsy revealed higher diagnostic yield and clinical utility than did forceps biopsy. However, procedure-related complications were higher in the cryobiopsy group. The choice of bronchoscopic biopsy procedure for patients with DPLD depends on the clinicalradiologic context.

Ocular comfort observed with three marketed solutions

Purpose: This study evaluated comfort (Visual Analog Scale 0-100, 100 = best comfort imaginable) of 2 multi-purpose solutions and 1 peroxide solution worn with 3 ACUVUE® brand contact lenses for 45 and 120 minutes.

Bacterial biofilm in silver-impregnated contact lens cases

PurposeThis study investigated the efficacy of pre-conditioning lens cases on bacterial biofilm formation and removal. MethodsSilver impregnated (MicroBlock / ProGuard™ & i-Clean) and control storage cases were pre-conditioned for 24 h with their respective multipurpose solutions (MPDSs). Cases were then inoculated with 2 ml of 106 CFU/mL of ocular isolates of either P. aeruginosa or S. aureus and incubated for 48 h. Cases were subsequently disinfected (4−6 hours) as per the manufacturer’s recommended disinfecting time (MRDT) followed by the recommended case hygiene procedures - recapping wet (MicroBlock / ProGuard™ cases only) or rinse and air-dry or rinse, tissue-wipe and air dry (mechanical disruption). Surviving bacteria were enumerated using standard techniques. ResultsPre-conditioning the MicroBlock / ProGuard™ cases with MPDS significantly reduced biofilm formation (-1.1 log10 CFU, p < 0.01 for P. aeruginosa & -1.3 log10, p < 0.001, CFU for S. aureus) compared to the i-Clean lens cases. Maintaining the MicroBlock / ProGuard™ lens cases wet after the MRDT resulted in partial removal of bacterial biofilms (-2.9 log10 CFU, p < 0.001 for P. aeruginosa and -2.6 log10 CFU, p < 0.001 for S. aureus). Air-drying of all three types of lens storage cases after MRDT significantly reduced the bacterial biofilm (-5.4 log10 CFU, p < 0.001 for P. aeruginosa and -3.5 log10 CFU, p < 0.001 for S. aureus). Mechanical disruption produced the greatest reduction in the levels of bacterial biofilm in all 3 types of lens cases tested (-6.8 log10 CFU, p < 0.001 for P. aeruginosa and -4.5 log10 CFU, p < 0.001 for S. aureus). Synergi MPDS was significantly better than AQuify MPDS in removing bacterial biofilm from all 3 lens case types for case hygiene treatments with an air-drying step. ConclusionPre-conditioning of silver-impregnated ProGuard™ lens cases inhibited initial bacterial biofilm formation. Synergi MPDS was more effective than AQuify MPDS in removing bacterial biofilm in silver impregnated cases and tissue-wiping significantly improved biofilm removal.

Diverse application and future prospects for commercial cultivation of microalgae species: A review

Industrial revolutions, advancements in health care, pharmaceuticals, transportation can be attributed to advancements made in the field of science and technology. Environment and natural resources has paid a heavy cost for most of industrial development. Rapid depletion of non-renewable sources of energy eventually leading towards the energy crisis, direct or indirect release of industrial effluents into soil and natural water bodies, global warming are among major consequences of industrialization. Ever since these environmental concerns have been recognized substantial studies have been conducted to minimize, control pollution and restore environment and natural resources. Among several measures cultivation of algae on large scale stands out to be a multipurpose solution. Inherent potential of microalgae species to accumulate lipids makes algae an efficient source of biofuel. Beside this ability of algae to detoxify polluted water and industrial effluent support utilization of algae for environment management and restoration. Efficient CO2 fixation, ability to tolerate wide range of environmental conditions, minimal nutritional requirements further support commercial cultivation of algal species to achieve their widespread application. However, efforts are required to develop large scale cultivation protocols (beyond the range of photobioreactors) so as to achieve practical applicability of algae and their products. Alongwith, cultivation protocols there is simultaneous need of either selection of naturally occurring high yielding strains / species or genetic improvement. Standardization of optimum cultivation conditions along with harvesting procedure is equally important.

Diversity of Ocular Surface Bacterial Microbiome Adherent to Worn Contact Lenses and Bacterial Communities Associated With Care Solution Use.

This study assessed microbiome adherent to contact lenses and defined the bacterial communities associated with use of lens care solutions. Among 84 lenses screened for adherent ocular surface bacterial microbiome using 16S rRNA molecular amplification, 63 (75%) generated bacterial-specific amplicons processed using the Ion Torrent Personal Genome Machine workflow. Data were stratified by solution use (peroxide vs. polyhexamethylene biguanide [PHMB]-preserved multipurpose solution [MPS]). Diversity of lens-adherent microbiome was characterized using Shannon diversity index and richness index. Data were analyzed using principal components analysis and Kruskal-Wallis tests. We identified 19 phyla and 167 genera of bacteria adherent to the lenses. Proteobacteria was the most abundant phyla, followed by Firmicutes and Actinobacteria. The most abundant bacterial genera (>1% abundance) were Ralstonia, Enterococcus, Streptococcus, Halomonas, Corynebacterium, Staphylococcus, Acinetobacter, Shewanella, Rhodococcus, and Cobetia. Sixteen of 20 lenses (80%) negative for bacterial DNA were worn by participants using peroxide solutions while only 4 (20%) were MPS-treated lenses (P=0.004). Genera diversity of lens-adherent microbiome showed a significant increase in MPS-treated lenses compared with peroxide (P=0.038). Abundance of Corynebacterium, Haemophilus, and Streptococcus were increased 4.3-, 12.3-, and 2.7-fold, respectively, in the MPS group compared with peroxide (P=0.014, 0.006, 0.047, respectively). Commensal, environmental, and pathogenic bacteria known to be present in the conjunctival microbiome can be detected on worn contact lenses. Although most contact lenses worn by asymptomatic wearers harbor bacterial DNA, compared with peroxide, lenses stored in a PHMB-preserved MPS have more quantifiable, abundant, and diverse bacterial communities adherent to them.

Risk factors associated with contamination of orthokeratology lens cases

PurposeTo evaluate the risk factors associated with contamination of lens cases in a group of orthokeratology (ortho-k) lens wearers. MethodOrtho-k patients attending the Contact Lens Clinic of the Hospital were required to complete a checklist about their routine daily care and handling of lens cases. Their cases were then collected for analysis. Contamination was evaluated by determining the optical density (OD) of crystal violet stained biofilm present in the cases. OD values were divided into three groups, lower, middle, and upper tertiles, and associations between risk factors were determined by multivariate analysis. ResultsA total of 194 subjects were recruited. Twenty-five subjects used cylindrical lens cases (CC), 98 flat cases with ridges (FCR), and 71 flat cases without ridges (FC). FCRs were the most heavily contaminated and CC showed least contamination (FCR > FC, OR 2.16, CI 1.11–4.18, p = 0.023; FCR > CC, OR 8.86, CI 2.97–26.44, p <0.001; FC > CC, OR 2.33, CI 1.35–12.45, p = 0.013). Replacing lens cases monthly significantly reduced the risk of high contamination (OR 0.013, CI 0.06-0.30, p < 0.001), compared to those used for three months. Cases that were not rinsed (OR 3.44, CI 1.50–7.86, p = 0.003) or rinsed by other methods (OR 4.07, CI 1.67–9.92, p = 0.002) had significantly more contamination, compared to those rinsed with multipurpose solution. Lens cases, which were not dried (OR 11.36, CI 2.06–62.93, p = 0.005) or air-dried (OR 8.71, CI 1.16–65.56, p = 0.036), showed more contamination compared to those wiped with tissue daily. ConclusionCase design (cylindrical), monthly replacement, daily rinsing with MPS, and wiping with tissue daily can effectively reduce biofilm formation in contact lens cases.

Videokeratoscopic assessment of silicone hydrogel contact lens wettability using a new in-vitro method

PurposeThe aim of the study was to assess the surface wettability of new-generation silicone hydrogel (SiH) contact lenses (CLs) videokeratoscopically using a new in-vitro method under office conditions. MethodVideokeratoscopic methodology was used to compare time-dependent CL wettability on an in-vitro cornea model. The model cornea was a polished chrome surface coating a Teflon form. It was prepared with a base curve of 8.7 mm and a diameter of 15 mm. Laboratory temperature and humidity were controlled. Before and after placing CLs on the on the model cornea, Bausch + Lomb Biotrue® multi-purpose solution (MPS) was dropped to simulate the pre-lens and post-lens film layer. Fanfilcon A, Senofilcon A, Samfilcon A, and Lotrafilcon B CLs with -3.00D were used, and images were taken with the videokeratoscopic method for testing. In the control group, the same procedure was performed without placing CLs. The images of CLs at 0, 60, 90, 120, 150, and 180 s were taken. Distortions and gaps seen in rings were recorded. The areas in rings were calculated in pixels using İmageJ. ResultsWhen CLs were examined, statistical differences were found among average pixel values (p < 0,001). The average pixel value was 131877.4 in the Samfilcon group, 116125.5 in the Senofilcon group, 137893.2 in the Fanfilcon group, 125578.3 in the Lotrafilcon group, and 124984.6 in the control group. No difference was found between the average values of the Lotrafilcon group and the control group. Differences were found between the average values of all other groups. DiscussionThe results obtained showed that videokeratoscopy was an effective method for in-vitro testing of CL wettability. It was found that SiH lenses displayed different performance under office conditions depending on materials and technologies used for wetting the lens surface. It was shown that lens surface wettability could be measured with a repeatable and new method when the factors affecting surface wetness and image quality were ruled out.

Learning analytics performance improvement design (LAPID) in higher education: Framework and concerns

Learning Analytics Dashboards (LAD) promise to disrupt the Higher Education (HE) teaching practice. Current LAD research portrays a near future of e-teaching, empowered with the ability to predict dropouts, to validate timely pedagogical interventions and to close the instructional design loop. These dashboards utilize machine learning, big data technologies, sophisticated artificial intelligence (AI) algorithms, and interactive visualization techniques. However, alongside with the desired impact, research is raising significant ethical concerns, context-specific limitations and difficulties to design multipurpose solutions. We revisit the practice of managing by the numbers and the theoretical origins of dashboards within management as a call to reevaluate the “datafication” of learning environments. More specifically, we highlight potential risks of using predictive dashboards as black boxes to instrumentalize and reduce learning and teaching to what we call “teaching by the numbers”. Instead, we suggest guidelines for teachers’ LAD design, that support the visual description of actual learning, based on teachers’ prescriptive pedagogical intent. We conclude with a new user-driven framework for future LAD research that supports a Learning Analytics Performance Improvement Design (LAPID).