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R White - One of the best experts on this subject based on the ideXlab platform.
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Bacterial colonization of rigid gas permeable and hydrogel contact lenses by Staphylococcus aureus
Journal of Industrial Microbiology and Biotechnology, 2000Co-Authors: C L Schultz, K S Kunert, R WhiteAbstract:ATCC 6538 and a clinical isolate of S. aureus from a bacterial keratitis patient were examined for their ability to adhere to etafilcon A, Polymacon, silafocon, and pauflufocon A, B and C contact lenses. Both isolates adhered more to the rigid gas permeable (RGP) materials than to the hydrogel lenses tested ( P
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Bacterial colonization of rigid gas permeable and hydrogel contact lenses by Staphylococcus aureus
Journal of Industrial Microbiology and Biotechnology, 2000Co-Authors: C L Schultz, K S Kunert, R WhiteAbstract:ATCC 6538 and a clinical isolate of S. aureus from a bacterial keratitis patient were examined for their ability to adhere to etafilcon A, Polymacon, silafocon, and pauflufocon A, B and C contact lenses. Both isolates adhered more to the rigid gas permeable (RGP) materials than to the hydrogel lenses tested (P < 0.05). S. aureus ATCC 6538 adhered to the etafilcon A material to a greater extent than did the clinical isolate (P < 0.05). there were no statistically significant differences in the recovery of staphylococci from unworn lens materials when surface area, composition and ionicity were evaluated for either the hydrogel or rgp lenses tested against lenses of a similar type. however, differences were observed when hydrogel lenses were evaluated against rgp lenses (P < 0.05). these differences may be related to water content. Journal of Industrial Microbiology & Biotechnology (2000) 24, 113–115.
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Bacterial adhesion measurements on soft contact lenses using a Modified Vortex Device and a Modified Robbins Device
Journal of Industrial Microbiology, 1995Co-Authors: C L Schultz, M R Pezzutti, D Silor, R WhiteAbstract:S. marcescens 8100 and P. aeruginosa 15442 were used to study bacterial adhesion to hydrogel contact lenses which had not been worn. Bacterial removal from unworn lens materials was assessed with a calibrated vortex device modified with a digital rpm readout and fitted with a test tube attachment (MVD). The MVD, which relies on a whirlpool-like force to remove the bacteria, showed that bacteria adhered to the same degree to etafilcon A, vifilcon A and Polymacon lenses under standardized conditions. Tracking the isoenzyme patterns of these bacterial species over time showed instability of S. marcescens upon repeated passage. This instability was not evident with P. aeruginosa . Bacterial adhesion of P. aeruginosa 15442, to human worn and unworn etafilcon A materials was determined with a Modified Robbins Device. The MRD was closed off at both ends stopping medium and bacterial movement after 1 h of fluid flow over the lens surface. The results show that immediately following this 1-h period more bacteria adhere to unworn contact lenses than to worn lenses. However, bacterial counts were equivalent on worn and unworn lenses following 5 h of static incubation.
Lisa D. Kelly - One of the best experts on this subject based on the ideXlab platform.
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The effect of concurrent pseudomonas or xanthomonas exposure on adherence of acanthamoeba castellanii to soft contact lenses
Graefe's Archive for Clinical and Experimental Ophthalmology, 1996Co-Authors: Lisa D. KellyAbstract:• Background: Approximately 85% of Acanthamoeba -contaminated contact lens systems in asymptomatic patients have concurrent bacterial contamination. Pseudomonas aeruginosa and Xanthomonas maltophilia are common contect lens contaminants; we investigated the effect of coincubation of Acanthamoeba adherence to contact lenses. • Methods: A. castellanii , 1 × 10^5 organisms/ml, was coincubated with P. aeruginosa or X. maltophilia , 1 × 10^8 CFU/ml in phosphate-buffered saline. Sterile, unworn Polymacon, etafilcon A or lidofilcon contact lens were investigated. The experimental groups were: (I) lenses exposed to bacteria for 1 h, then Acanthamoeba for 2 h; (II) lenses exposed concurrently to bacteria and Acanthamoeba for 2 h; (III) Acanthamoeba coincubated with bacteria for 24 h, then lenses exposed for 2 h; (IV) lenses exposed to Acanthamoeba for 2 h (control). • Results: For all experimental groups, Acanthamoeba adherence was greater to lidofilcon than to Polymacon and etafilcon. For both P. aeruginosa and X. maltophilia , neither group I nor group II displayed greater Acanthamoeba adherence than group IV. Group III exhibited significantly less adherence than group IV for lidofilcon and Polymacon. The decrease in group III adherence reflected an overall decrease in Acanthamoeba trophozoite concentration. • Conclusion: Short bacteria/ Acanthamoeba coincubation times did not result in increased Acanthamoeba adherence. Twenty-four-hour coincubation resulted in decreased adherence for Pseudomonas and unchanged adherence rates for Xanthomonas . This model suggests that Pseudomonas or Xanthomonas co-contamination does not necessarily facilitate quantitative Acanthamoeba contact lens adherence.
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The effect of concurrent Pseudomonas or Xanthomonas exposure on adherence of Acanthamoeba castellanii to soft contact lenses.
Graefe's Archive for Clinical and Experimental Ophthalmology, 1996Co-Authors: Lisa D. KellyAbstract:• Background: Approximately 85% of Acanthamoeba-contaminated contact lens systems in asymptomatic patients have concurrent bacterial contamination. Pseudomonas aeruginosa and Xanthomonas maltophilia are common contect lens contaminants; we investigated the effect of coincubation of Acanthamoeba adherence to contact lenses. • Methods: A. castellanii, 1 × 105 organisms/ml, was coincubated with P. aeruginosa or X. maltophilia, 1 × 108 CFU/ml in phosphate-buffered saline. Sterile, unworn Polymacon, etafilcon A or lidofilcon contact lens were investigated. The experimental groups were: (I) lenses exposed to bacteria for 1 h, then Acanthamoeba for 2 h; (II) lenses exposed concurrently to bacteria and Acanthamoeba for 2 h; (III) Acanthamoeba coincubated with bacteria for 24 h, then lenses exposed for 2 h; (IV) lenses exposed to Acanthamoeba for 2 h (control). • Results: For all experimental groups, Acanthamoeba adherence was greater to lidofilcon than to Polymacon and etafilcon. For both P. aeruginosa and X. maltophilia, neither group I nor group II displayed greater Acanthamoeba adherence than group IV. Group III exhibited significantly less adherence than group IV for lidofilcon and Polymacon. The decrease in group III adherence reflected an overall decrease in Acanthamoeba trophozoite concentration.
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Quantitative comparison of Acanthamoeba castellanii adherence to rigid versus soft contact lenses.
The CLAO journal : official publication of the Contact Lens Association of Ophthalmologists Inc, 1995Co-Authors: Lisa D. Kelly, David Long, Dipak MitraAbstract:We evaluated quantitative differences in adherence of Acanthamoeba castellanii trophozoites and cysts to new unworn contact lenses as a function of contact lens type and duration of exposure. Daily wear soft (Polymacon), disposable soft (etafilcon A), rigid gas permeable (RGP) (siloxane acrylate), and polymethylmethacrylate (PMMA) contact lenses were exposed to 1 x 10(5)/mL log phase A. castellanii (trophozoite:cyst ratio 90:10) for 10 seconds, 30 minutes, 60 minutes, and 120 minutes. The number of adherent organisms was determined by light microscopy and confirmed by scanning electron microscopy. Rates of cyst adherence were similar among contact lens types. We observed significantly greater adherence of trophozoites to RGP and PMMA lenses compared with soft contact lenses (P < 0.05). This difference in trophozoite adherence was significant at all four time periods (P < 0.05). Our findings show that A. castellanii trophozoites and cysts adhere to both soft and rigid contact lens types. We also found that although trophozoite adherence increases as a function of duration of exposure, adherent organisms were observed with exposure times as brief as 10 seconds. This suggests that all contact lens types may be at risk for Acanthamoeba attachment and that even minimal exposure times may be sufficient for lens contamination.
Lyndon Jones - One of the best experts on this subject based on the ideXlab platform.
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Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro.
Contact Lens and Anterior Eye, 2018Co-Authors: Negar Babaei Omali, Lakshman N. Subbaraman, Miriam Heynen, Zohra Fadli, Chantal Coles-brennan, Lyndon JonesAbstract:Abstract Purpose To determine and compare the levels of surface versus bulk active lysozyme deposited on several commercially available hydrogel contact lens materials. Methods Hydrogel contact lens materials [Polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon and etafilcon A with polyvinylpyrrolidone (PVP)] were incubated in an artificial tear solution for 16 h. Total activity was determined using a standard turbidity assay. The surface activity of the deposited lysozyme was determined using a modified turbidity assay. The amount of active lysozyme present within the bulk of the lens material was calculated by determining the difference between the total and surface active lysozyme. Results The etafilcon A materials showed the highest amount of total lysozyme activity (519 ± 8 μg/lens, average of Moist and Define), followed by the ocufilcon material (200 ± 5 μg/lens) and these two were significantly different from each other (p Conclusions The surface and bulk activity of lysozyme deposited on contact lenses is material dependent. Lysozyme deposited on ionic, high water content lens materials such as etafilcon A show significantly higher surface and bulk activity than many other hydrogel lens materials.
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Selectivity and localization of lysozyme uptake in contemporary hydrogel contact lens materials
Journal of Biomaterials Science Polymer Edition, 2017Co-Authors: Miriam Heynen, Lakshman N. Subbaraman, Negar Babaei Omali, Zohra Fadli, Chantal Coles-brennan, Lyndon JonesAbstract:AbstractThe purpose of this study was to investigate the early and selective uptake of lysozyme and the location of deposited lysozyme on contemporary hydrogel contact lens (CL) materials after exposure to an artificial tear solution (ATS) for 16 h. Seven different hydrogel CL materials [Polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon B, etafilcon A (Acuvue Moist), and etafilcon A (Acuvue Define)] were incubated in an ATS for various times. Total protein deposition was determined using a modified Bradford technique. Lysozyme, lactoferrin, and albumin deposition on CLs were determined using 125I-radiolabeling method. A confocal laser scanning microscopy (CLSM) technique was utilized to map the location of lysozyme uptake in an asymmetric environment. All lens materials had significant amounts of lysozyme after 1 min of exposure to ATS. After 16 h of incubation, higher levels of total protein deposited on the two etafilcon A-based lenses (Moist and Define), followed by ocufilcon B and both were...
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Comparison of biomicroscopic signs with different soft contact lens materials and care product combinations
Contact Lens and Anterior Eye, 2015Co-Authors: Andrew J. Plowright, Lyndon Jones, Philip B. Morgan, Sheila B. Hickson-curran, Sruthi Srinivasan, David A. Berntsen, Jason J. Nichols, Carole Maldonado-codinaAbstract:s / Contact Lens & Anterior Eye 38 (2015) e13–e46 e21 Results: Relative rates of bulk dehydration (RBD) were calculated as available water lost per minute and plotted against time to provide a rate profile of lens water loss behaviour. Profiles were observed to be characteristic of the hydrophilic monomers in the polymer. In the early stages of water loss polyHEMA and HEMA-PC materials showed higher relative rates of dehydrationwith steeper profiles than did HEMA-NVP hydrogels. Peak rates for Polymacon, omafilcon A and hilafilcon B were 0.50±0.08 RBD, 0.34±0.02 RBD and 0.27±0.01 RBD respectively (±SD). Conclusions: Although lenses of similar water contents behave similarly in terms of long-term cumulative water loss, the dynamics of water loss behaviour are material-specific. Some materials have relatively flat initial profiles whereas others have steep initial water loss-probably related to water binding characteristics of the polymer. It is logical to expect that flatter loss profiles would be associated with less dehydration during lens handling and insertion, which is the subject of ongoing exploration. Thomas Minchington, B.Sc. Biomedical Science, is a PhD student in the Biomaterials Research Unit at Aston University. He is currently researching the improvement of comfort in silicone and conventional hydrogel materials through the use of bound or sustained release additives. http://dx.doi.org/10.1016/j.clae.2014.11.021
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In vitro uptake and release of natamycin from conventional and silicone hydrogel contact lens materials.
Eye & Contact Lens: Science & Clinical Practice, 2013Co-Authors: Chau-minh Phan, Lakshman N. Subbaraman, Lyndon JonesAbstract:OBJECTIVES To investigate the uptake and release of the antifungal ocular drug, natamycin from commercially available conventional hydrogel (CH) and silicone hydrogel (SH) contact lens (CL) materials and to evaluate the effectiveness of this delivery method. METHODS Five commercial SH CLs (balafilcon A, comfilcon A, galyfilcon A, senofilcon A, and lotrafilcon B) and four CH CLs (etafilcon A, omafilcon A, Polymacon, vifilcon A) were examined in this study. These lenses were incubated with natamycin solubilized in dimethyl sulfoxide, and the release of the drug from these lenses, in Unisol 4 pH 7.4 at 32±1°C, was determined using UV-visible spectrophotometry at 305 nm over 24 hours. RESULTS There was a significant uptake of natamycin between 0 hour and 24 hours (P 0.05). There was a significant difference in release between all the SH materials (P 0.05). Overall, the release of natamycin was higher in CH than SH lenses (P
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Ocular Delivery Of Ketotifen Fumarate By Silicone Hydrogel And Conventional Hydrogel Contact Lens Materials
Investigative Ophthalmology & Visual Science, 2012Co-Authors: Anthony Soluri, Alex Hui, Lyndon JonesAbstract:24 hour uptake period for commercially available daily disposable lenses: () ocufilcon B, (q) etafilcon A (1 Day Moist), (¢) narafilcon A, (u) filcon II 3, (p) omafilcon A and (A) nelfilcon A. Values plotted are means ± standard deviations. Figure 2c: Cumulative release of ketotifen fumarate over the 24 hour release period for commercially available daily disposable lenses: () ocufilcon B, (q) etafilcon A (1 Day Moist), (¢) narafilcon A, (u) filcon II 3, (p) omafilcon A and (A) nelfilcon A. Values plotted are means ± standard deviations. Figure 1b: Cumulative uptake of ketotifen fumarate over the 24 hour uptake period for commercially available silicone hydrogel lenses: () balafilcon A, (q) lotrafilcon B, (¢) galyfilcon A, (u) senofilcon A and (p) comfilcon A. Values plotted are means ± standard deviations. Figure 2b: Cumulative release of ketotifen fumarate over the 24 hour release period for commercially available silicone hydrogel lenses: () balafilcon A, (q) lotrafilcon B, (¢) galyfilcon A, (u) senofilcon A and (p) comfilcon A. Values plotted are means ± standard deviations. Figure 1a: Cumulative uptake of ketotifen fumarate over the 24 hour uptake period for commercially available conventional lenses: () etafilcon A (Acuvue2), (q) alphafilcon A and (¢) Polymacon. Values plotted are means ± standard deviations. Figure 2a: Cumulative release of ketotifen fumarate over the 24 hour release period for commercially available conventional lenses: () etafilcon A (Acuvue2), (q) alphafilcon A and (¢) Polymacon. Values plotted are means ± standard deviations. •Etafilcon A lenses, ocufilcon B and balafilcon A showed the greatest uptake and release of ketotifen after 24 hours. •Varying the concentration of the doping solution does have an effect on the total ketotifen taken up and released. •The recommended dosage schedule when using a 0.025% ketotifen ophthalmic solution is 2 drops per eye per day, or 25μg of per day. All the contact lenses tested released more than this amount, which means these lenses are capable of taking up and releasing a potentially clinically significant amount of ketotifen. •These lenses, however, release their loaded ketotifen very quickly, as is apparent in Figures 2a-c, generally reaching release plateaus after one to three hours. This limitation would seem to prevent this drug delivery system from being used with extended wear contact lenses. •However, the method of drug loading employed in this study may be sufficient for a daily disposable wear modality. Ocular Delivery Of Ketotifen Fumarate By Silicone Hydrogel And Conventional Hydrogel Contact Lens Materials #6101 A. Soluri, A. Hui, L. Jones
C L Schultz - One of the best experts on this subject based on the ideXlab platform.
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Bacterial colonization of rigid gas permeable and hydrogel contact lenses by Staphylococcus aureus
Journal of Industrial Microbiology and Biotechnology, 2000Co-Authors: C L Schultz, K S Kunert, R WhiteAbstract:ATCC 6538 and a clinical isolate of S. aureus from a bacterial keratitis patient were examined for their ability to adhere to etafilcon A, Polymacon, silafocon, and pauflufocon A, B and C contact lenses. Both isolates adhered more to the rigid gas permeable (RGP) materials than to the hydrogel lenses tested ( P
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Bacterial colonization of rigid gas permeable and hydrogel contact lenses by Staphylococcus aureus
Journal of Industrial Microbiology and Biotechnology, 2000Co-Authors: C L Schultz, K S Kunert, R WhiteAbstract:ATCC 6538 and a clinical isolate of S. aureus from a bacterial keratitis patient were examined for their ability to adhere to etafilcon A, Polymacon, silafocon, and pauflufocon A, B and C contact lenses. Both isolates adhered more to the rigid gas permeable (RGP) materials than to the hydrogel lenses tested (P < 0.05). S. aureus ATCC 6538 adhered to the etafilcon A material to a greater extent than did the clinical isolate (P < 0.05). there were no statistically significant differences in the recovery of staphylococci from unworn lens materials when surface area, composition and ionicity were evaluated for either the hydrogel or rgp lenses tested against lenses of a similar type. however, differences were observed when hydrogel lenses were evaluated against rgp lenses (P < 0.05). these differences may be related to water content. Journal of Industrial Microbiology & Biotechnology (2000) 24, 113–115.
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Bacterial adhesion measurements on soft contact lenses using a Modified Vortex Device and a Modified Robbins Device
Journal of Industrial Microbiology, 1995Co-Authors: C L Schultz, M R Pezzutti, D Silor, R WhiteAbstract:S. marcescens 8100 and P. aeruginosa 15442 were used to study bacterial adhesion to hydrogel contact lenses which had not been worn. Bacterial removal from unworn lens materials was assessed with a calibrated vortex device modified with a digital rpm readout and fitted with a test tube attachment (MVD). The MVD, which relies on a whirlpool-like force to remove the bacteria, showed that bacteria adhered to the same degree to etafilcon A, vifilcon A and Polymacon lenses under standardized conditions. Tracking the isoenzyme patterns of these bacterial species over time showed instability of S. marcescens upon repeated passage. This instability was not evident with P. aeruginosa . Bacterial adhesion of P. aeruginosa 15442, to human worn and unworn etafilcon A materials was determined with a Modified Robbins Device. The MRD was closed off at both ends stopping medium and bacterial movement after 1 h of fluid flow over the lens surface. The results show that immediately following this 1-h period more bacteria adhere to unworn contact lenses than to worn lenses. However, bacterial counts were equivalent on worn and unworn lenses following 5 h of static incubation.
Mayorga, Miriam Teresa - One of the best experts on this subject based on the ideXlab platform.
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In vitro Study about the proliferation of Candida albicans in different material soft contact lenses
Universidad de La Salle. Revistas. Ciencia y Tecnología para la Salud Visual y Ocular., 2017Co-Authors: Zambrano Liliana, Parra G., Claudia M., Mayorga, Miriam TeresaAbstract:Debido a la creciente importancia que tiene el uso de lentes de contacto blandos para corregir ametropías a nivel mundial y en la población colombiana, sumado a la capacidad de la levadura Candida albicans de producir enfermedades oculares por el uso de los mismos, llegando a ser uno de los principales agentes infecciosos; en este estudio se evaluó la capacidad de Candida albicans de proliferar en 5 diferentes materiales de lentes de contacto blandos hidrofílicos, tres de ellos de hidrogel (Alphafilcon A, Omafilcon A, Polymacon) y dos de hidrogel silicona (Balafilcon A y Lotrafilcon A). Se encontró que la levadura puede proliferar en el material Alphafilcon A en mayor proporción, y en menor grado en Omafilcon A y lotrafilcon A.The use of soft contact lenses has an increasing importance to correct ametropias at world-wide level and in the Colombian population, besides, the yeast Candida albicans has the ability to produce ocular diseases by using the lenses, which has become in one of the main infectious agents. The proliferation capability of Candida albicans was evaluated in 5 different hydrophilic soft contact lenses, three of them of hidrogel (Alphafilcon A, Omafilcon A, Polymacon) and two of hidrogel silicone (Lotrafilcon A and Balafilcon A). Yeast proliferates in the Alphafilcon A material in greater proportion, and in smaller degree in Omafilcon A and Lotrafilcon A
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Estudio in vitro de la capacidad de proliferación de Candida albicans en diferentes materiales de lentes de contacto blandos
2006Co-Authors: Zambrano Liliana, Parra, Claudia Marcela, Mayorga, Miriam TeresaAbstract:The use of soft contact lenses has an increasing importance to correct ametropias at world-wide level and in the Colombian population, besides, the yeast Candida albicans has the ability to produce ocular diseases by using the lenses, which has become in one of the main infectious agents. The proliferation capability of Candida albicans was evaluated in 5 different hydrophilic soft contact lenses, three of them of hidrogel (Alphafilcon A, Omafilcon A, Polymacon) and two of hidrogel silicone (Lotrafilcon A and Balafilcon A). Yeast proliferates in the Alphafilcon A material in greater proportion, and in smaller degree in Omafilcon A and Lotrafilcon A.Debido a la creciente importancia que tiene el uso de lentes de contacto blandos para corregir ametropías a nivel mundial y en la población colombiana, sumado a la capacidad de la levadura Candida albicans de producir enfermedades oculares por el uso de los mismos, llegando a ser uno de los principales agentes infecciosos; en este estudio se evaluó la capacidad de Candida albicans de proliferar en 5 diferentes materiales de lentes de contacto blandos hidrofílicos, tres de ellos de hidrogel (Alphafilcon A, Omafilcon A, Polymacon) y dos de hidrogel silicona (Balafilcon A y Lotrafilcon A). Se encontró que la levadura puede proliferar en el material Alphafilcon A en mayor proporción, y en menor grado en Omafilcon A y lotrafilcon A
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Estudio in vitro de la capacidad de proliferación de Candida albicans en diferentes materiales de lentes de contacto blandos
Ediciones Unisalle, 2006Co-Authors: Zambrano Liliana, Parra G., Claudia M., Mayorga, Miriam TeresaAbstract:Debido a la creciente importancia que tiene el uso de lentes de contacto blandos para corregir ametropías a nivel mundial y en la población colombiana, sumado a la capacidad de la levadura Candida albicans de producir enfermedades oculares por el uso de los mismos, llegando a ser uno de los principales agentes infecciosos; en este estudio se evaluó la capacidad de Candida albicans de proliferar en 5 diferentes materiales de lentes de contacto blandos hidrofílicos, tres de ellos de hidrogel (Alphafilcon A, Omafilcon A, Polymacon) y dos de hidrogel silicona (Balafilcon A y Lotrafilcon A). Se encontró que la levadura puede proliferar en el material Alphafilcon A en mayor proporción, y en menor grado en Omafilcon A y lotrafilcon A