UNASSIGNED: To investigate the physical properties of commercially available multipurpose soft contact lens solutions in Ghana.
UNASSIGNED: pH (Kelilong ICL-099 pH meter, China), osmolality (OSMOMAT 3000, GONOTEC, Germany), surface tension (Sigma 700 Tensiometer, Sweden), and viscosity (CFOC-200 Viscometer, Cannon Company, USA) of various soft contact lens multipurpose solutions (MPS) were measured in triplicates at room temperature. Viscosity measurements were also taken at 34 °C ocular surface temperature. The solutions examined were Opti-Free Replenish (OFR), Trufresh (TF), Avizor (AV), Freshlook (FL), and Refresh (RF).
UNASSIGNED: Several solutions were largely hypo-osmotic in the range of 108-231 mOsm/kg, the exception being Avizor, which had osmolality values that were closer to human tears (301 ± 0.58 mOsm/kg). The range of pH values of the solutions (6.33-8.24, mean (SD) = 7.53 ± 0.18) fell within the reported tolerable range for the ocular surface (6.20-9.00). Surface tension values ranged from 35.86 to 42.27 mNm with a mean of 38.49 ± 2.32 mNm. The average viscosity of most solutions at room temperature (25 °C) was 1.44 ± 0.49 cP with a range of 1.04-2.15 cP. Significantly lower values ranging from 0.79 to 1.58 cP were obtained at ocular surface temperature (34 °C), p = 0.0001).
UNASSIGNED: The physical properties of many of the solutions used as MPS in Ghana are markedly variable. Nevertheless, pH, surface tension, and viscosity fall within the acceptable limits of ocular physiological tolerance; except for osmolality, which majority were outside the reported tolerable range for the ocular surface. This information may partly explain the reason some patients exhibit strong preferences for certain care systems and should aid clinical decision-making when prescribing eye care systems to patients.

UNASSIGNED: This study compared the anti-pseudomonal effects between nephrite-impregnated contact lenses (CLs) and conventional and cosmetic CLs.
UNASSIGNED: After inoculation with Pseudomonas aeruginosa (P.aeruginosa), we counted the number of bacteria on the CL surface and observed each surface using atomic force microscopy (AFM) and scanning electron microscopy (SEM). To estimate potential harm of nephrite-impregnated CLs, we conducted a safety test using a rabbit model, treated with all CL types.
UNASSIGNED: Both conventional and cosmetic CLs (n = 258 ± 2.9 × 104, 368 ± 2.2 × 104) showed significantly decreased number of attached bacteria when compared with those without nephrite impregnation (n = 134 ± 0.8 × 104, 238 ± 2.5 × 104, p < 0.0001, respectively). AFM and SEM revealed that P. aeruginosa was less attached to the nephrite-impregnated CLs than to the conventional and cosmetic CLs, although those with nephrite impregnation had rougher surface. In the safety test, there were no significant differences in the findings between four groups, and the clarity and stability of all corneas were preserved.
UNASSIGNED: Nephrite may be used as a next-generation substance to reduce infectious keratitis caused by P. aeruginosa when added to CLs.

BACKGROUND: Midday fogging is a complication of scleral lens (SL) wear that interrupts clear vision during the course of wear. SLs can be made with a variety of gas permeable materials, sizes and surface treatments, and various solutions are available for storing the lenses and for filling them before application on the eye. Many of these factors have been implicated as possible contributors to midday fogging. This study explored the lens and solution properties in habitual SL wearers with and without midday fogging.
METHODS: In this prospective study, 48 habitual SL wearers were evaluated and asked to report whether they experienced midday fogging and if they removed their lenses during the day. They completed the Ocular Surface Disease Index (OSDI), which is a validated tool for dry eye assessment. Lens parameters (material, coatings and diameter) and lens storage and filling solutions were documented. Backward elimination of regression terms evaluated the lens and solution properties in those with and without fogging. OSDI scores were compared using the Mann-Whitney analysis.
RESULTS: Collectively, the lens properties and solutions accounted for 27.7% of the variance related to midday fogging. None of the factors alone had a significant impact upon midday fogging. The median (interquartile range) OSDI score for those with fogging [37 (35)] was significantly different from those without fogging [10 (15)], with the scores corresponding to severe dry eye and normal eyes, respectively.
CONCLUSIONS: SL wearers with midday fogging exhibited similar symptoms to patients with severe dry eye. Lens and solution characteristics may play a small role in patients with midday fogging, although changing just a single factor is not likely to impact its presence.

OBJECTIVE: Despite the increasing prevalence of contact lens (CL) wear, knowledge and compliance with proper care remain suboptimal. This study aims to assess the level of knowledge and compliance with lens care practices in patients attending a third-level institution in Northeast Mexico.
METHODS: A cross-sectional study using a self-administered online survey was conducted. Patients at the Instituto Tecnolgico de Monterrey were invited to participate. The questionnaire consisted of three sections: demographic data and CL information, CL practices, and CL care knowledge. Participants responding correctly to 6/7 questions from the second and third sections were classified as having good compliance and good knowledge, respectively. Predictive factors for good compliance and knowledge were calculated using a logistic regression model.
RESULTS: A total of 287 users participated in the study. The median age was 25 (14-78) years with a female (n = 221, 77 %) predominance. Good knowledge was observed in 215 (74.9 %), whereas only 42 (14.6 %) presented good compliance. Failing to replace CL as prescribed (n = 199, 69.3 %) and sleeping with the devices (n = 198, 69 %) were the most frequent practices causing non-compliance. Whereas prohibition of swimming with CL was the least known practice (n = 74, 25 %). Users with recent (≤5 years) wearing experience were more likely to present good knowledge (OR 2.19, p = 0.014) and compliance (OR 3.15, p < 00.01). No statistical correlation was established between knowledge and compliance.
CONCLUSIONS: Non-compliance and lack of knowledge of proper CL care were prevalent among in this population. Long-term CL users were at higher risk of non-compliance and lack of knowledge. Moreover, knowledge was not related to compliance; therefore, different strategies must be implemented to reduce CL misconduct.

The free living Acanthamoeba spp. are ubiquitous amoebae associated with potentially blinding disease known as Acanthamoeba keratitis (AK) and a fatal central nervous system infection granulomatous amoebic encephalitis (GAE). With the inherent ability of cellular differentiation, it can phenotypically transform to a dormant cyst form from an active trophozoite form. Acanthamoeba cysts are highly resistant to therapeutic agents as well as contact lens cleaning solutions. One way to tackle drug resistance against Acanthamoeba is by inhibiting the formation of cysts from trophozoites. The biochemical analysis showed that the major component of Acanthamoeba cyst wall is composed of carbohydrate moieties such as galactose and glucose. The disaccharide of galactose and glucose is lactose. In this study, we analyzed the potential of lactase enzyme to target carbohydrate moieties of cyst walls. Amoebicidal assessment showed that lactase was ineffective against trophozoite of A. castellanii but enhanced amoebicidal effects of chlorhexidine. The lactase enzyme did not show any toxicity against normal human keratinocyte cells (HaCaT) at the tested range. Hence, lactase can be used for further assessment for development of potential therapeutic agents in the management of Acanthamoeba infection as well as formulation of effective contact lens disinfectants.

OBJECTIVE: The purpose of this study was to explore the impact of several contact lens (CL) care solutions on the removal of proteins and lipids, and how deposit removal impacts bacterial adhesion and solution disinfection.
METHODS: Lysozyme and lipid deposition on three ortho-k (rigid) and two soft CL materials were evaluated using an ELISA kit and gas chromatography respectively. Bacterial adhesion to a fluorosilicone acrylate material using Pseudomonas aeruginosa with various compositions of artificial tear solutions (ATS), including with denatured proteins, was also investigated. The impact of deposition of the different formulations of ATS on biofilm formation was explored using cover slips. Finally, the lysozyme and lipid cleaning efficacy and disinfection efficacy against P. aeruginosa and Staphylococcus aureus of four different contact lens care solutions were studied using qualitative analysis.
RESULTS: While maximum lysozyme deposition was observed with the fluorosilicone acrylate material (327.25 ± 54.25 µg/lens), the highest amount of lipid deposition was recorded with a fluoro-siloxanyl styrene material (134.71 ± 19.87 µg/lens). Adhesion of P. aeruginosa to fluorosilicone acrylate lenses and biofilm formation on cover slips were significantly greater with the addition of denatured proteins and lipids. Of the four contact lens care solutions investigated, the solution based on povidone-iodine removed both denatured lysozyme and lipid deposits and could effectively disinfect against P. aeruginosa and S. aureus when contaminated with denatured proteins and lipids. In contrast, the peroxide-based solution was able to inhibit P. aeruginosa growth only, while the two multipurpose solutions were unable to disinfect lenses contaminated with denatured proteins and lipids.
CONCLUSIONS: Bacterial adhesion and biofilm formation is influenced by components within artificial tear solutions depositing on lenses, including denatured proteins and lipids, which also affects disinfection. The ability of different solutions to remove these deposits should be considered when selecting systems to clean and disinfect ortho-k lenses.

OBJECTIVE: RigidCare is an electrolysis-based device that recently obtained approval from the US\'s FDA to sterilise microorganisms and remove proteins for orthokeratology (O-K) lenses. The study was conducted to investigate the device\'s performance in varied clinical circumstances.
METHODS: Trial lenses and private lenses were employed by O-K lens wearers from five hospitals for an evaluation of disinfection and sterilisation and an assessment of protein removal, respectively. Menicon multipurpose solution and protein remover were selected for use with the control group. Following the instructions, pre-cleaning lens samples, post-cleaning lens samples and residual solution samples of trial lenses of the experimental and control groups were collected for microorganism examinations by an experienced third-party testing organisation. The levels of protein deposition for these two approaches were rated by senior O-K experts. Categorical variables were analysed using statistical tests, such as the chi-squared test and Fisher\'s exact test.
RESULTS: The microbial positive rate detected from the pre-cleaning and post-cleaning lens samples and the residual solution of the trial lenses for the experimental and control group was 4/76 vs 1/74 (P = 0.37), 1/76 vs 0/74 (P = 1.00) and 0/76 vs 8/74 (P = 0.006), respectively. Following protein removal, the experimental group exhibited a significantly higher overall proportion of lenses rated as \'clean\' or with a \'mild deposit\' (96.4 %, 79/82) compared to the control group (85.7 %, 66/77), with a significant difference (P < 0.05).
CONCLUSIONS: This multi-center study demonstrated that RigidCare exhibited superior efficacy in disinfection, sterilisation and protein removal as compared to Menicon multipurpose solution and protein remover.

Several antimicrobial agents are commonly included in contact lens disinfectant solutions including chlorhexidine diacetate (CHX), polyhexamethylene biguanide (PHMB) or myristamidopropyl dimethylamine (MAPD); however, their mode of action, i.e. necrosis versus apoptosis is incompletely understood. Here, we determined whether a mechanism of cell death resembling that of apoptosis was present in Acanthamoeba castellanii of the T4 genotype (NEFF) following exposure to the aforementioned antimicrobials using the anticoagulant annexin V that undergoes rapid high affinity binding to phosphatidylserine in the presence of calcium, making it a sensitive probe for phosphatidylserine exposure. The results revealed that under the conditions employed in this study, an apoptotic pathway of cell death in this organism at the tested conditions does not occur. Our findings suggest that necrosis is the likely mode of action; however, future mechanistic studies should be accomplished in additional experimental conditions to further comprehend the molecular mechanisms of cell death in Acanthamoeba.

UNASSIGNED: Half of the individuals who wear contact lenses use reusable lenses that require proper care. Improper contact lens (CL) care and using inadequate disinfecting solutions can lead to lens contamination, CL-related microbial keratitis, and Acanthamoeba keratitis. Oxidative disinfecting solutions, such as hydrogen peroxide, show higher efficacy than multipurpose solutions. Povidone-iodine (PVP-I), an oxidative disinfectant used in ophthalmic surgery, has been proven to be safe and effective. The PVP-I system, a CL disinfecting solution developed in Japan, has demonstrated excellent antimicrobial and antiviral properties. Although CL discomfort does not have a risk of ocular disorders with poor visual prognosis, such as keratitis, CL discomfort can still lead to lens dropout and thus needs to be addressed. To mitigate CL discomfort, it is essential to use disinfecting solutions containing surfactants and wetting agents that improve wettability of the lens surface. A CL solution containing hyaluronic acid derivatives (HADs) as wetting agents that permanently adhere to the lens surface to improve wettability of the lens surface was developed in Japan. There is potential for HAD to be integrated into various solutions. This article reviews the efficacy of novel PVP-I-based disinfecting solution and HAD wetting agents.

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