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ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - CorneaProgram Number: 497 Poster Board Number: B0134Presentation Time: 10:30 AM - 12:15 PMSelenium covalently incorporated into the polymer of contact lenscase material inhibits bacterial biofilm formationTed W. Reid 1, 2 , Phat L. Tran 1 , Thomas Mosley 2 , Courtney Jarvis 1 ,Daniel Webster 4 , Robert E. Hanes 3 , Abdul Hamood 5 . 1 Ophthal &Visual Science, Texas Tech Univ Health Sciences Ctr, Lubbock, TX;2 Selenium Ltd., Lubbock, TX; 3 Selenium Ltd., Austin, TX; 4 CellBiology, Texas Tech University Health Sciences Ctr, Lubbock, TX;5 Microbiolgy, Texas Tech University Health Sciences Ctr, Lubbock,TX.Purpose: Contact lens case bacterial biofilm formation has become amajor cause of contact lens contamination. This is a serious problemsince it has been found that bacteria grow even in the presence ofcontact lens cleaning solution. Silver as an antimicrobial has beenincorporated into contact lens cases, however, silver has severaldrawbacks. Any patient with silver or metal allergies cannot use thesecases and silver has minimal effects against Staphylococcus aureus(S. aureus), Stenotrophomonas maltophilia (S. maltophilia), anddifferent fungi. In addition, silver is expensive and has to leach out ofthe case to be active. In contrast, selenium does not have to leach outof the material to be active since it kills by the catalytic formation ofsuperoxide radicals and it is much less expensive. Thus, this projectwas carried out to test the ability of selenium, covalently incorporatedinto the polymer of contact lens case material, to inhibit biofilmformation by different bacteria.Methods: A polymer of polypropylene was produced thatincorporated organo-selenium monomers into the final polymer. Thismaterial was then injection molded. The resulting material was testedfor its ability to inhibit biofilm formation. with silver or metalallergies cannot use these cases and silver has minimal effects againstS. aureus and S. maltophilia were tested since these bacteria areresistant to killing with silver. Pseudomonas aeruginosa and Serraciamarcessans were also tested. The bacteria were allowed to grow inthe presence of the polypropylene (with or without selenium) for 24hours. The bacteria were then removed by vortexing and assayed.The bacterial concentration was determined by a colony forming unitassay (plating on agar). The biofilm was also imaged by confocallaser scanning spectroscopy and was then quantitated by COMSTATanalysis.Results: Selenium containing polypropylene showed over 7 logs(complete) inhibition against S. aureus, S. maltophilia and P.aeruginosa, and also was fully active after soaking in PBS for theequivalent of 8 weeks. S. marcessans showed 4 logs of killing.Conclusions: The results showed that selenium covalentlyincorporated into a polypropylene polymer could be injection moldedyet showed total inhibition of S. aureus S. maltophilia and P.aeruginosa biofilm and was stable to soaking for 8 weeks.Commercial Relationships: Ted W. Reid, Selenium Ltd. (I),Selenium Ltd. (P); Phat L. Tran, None; Thomas Mosley, Selenium,Ltd. (E); Courtney Jarvis, None; Daniel Webster, None; Robert E.Hanes, Selenium, Ltd. (F), Selenium, Ltd. (I), Selenium, Ltd. (E),Selenium, Ltd. (P); Abdul Hamood, NoneProgram Number: 498 Poster Board Number: B0135Presentation Time: 10:30 AM - 12:15 PMEffect of Oxidation on Binding of Fatty Acids to PureVision andAcuvue Contact LensesThomas J. Millar, Burkhardt S. Schuett. School of Science andHealth, Univ of Western Sydney, Penrith, NSW, Australia.Purpose: Contamination reduces the longevity of contact lenses.Although lipids contaminate contact lenses, it is not known if this ispreferentially by oxidised lipids. Such knowledge can be useful indeveloping cleaning solutions.Methods: A Fenton reaction was optimized and used to prepareoxidized oleic acid and linolenic acid. The degree of oxidation wasquantified by measuring peroxides, malonyldialdehyde reactivespecies and build-up of polymerized aldehydes. Based on thesemeasurements, 14 C fatty acids were oxidised to different degrees.PureVision and Acuvue contact lenses were loaded with these at35°C and lipid binding was determined by measuring the ratio ofbound to unbound radioactivity.Results: The degree of oxidation using the Fenton reaction dependedon the amount of desaturation. With time, only peroxides wereformed from oleic acid whereas linolenic acid was eventually brokendown completely. It was determined that 20h incubation with50µg/mL of lipids gave optimal binding. Acuvue lenses bound ~50%more non-oxidised lipids than PureVision lenses. There was noincrease in binding of oxidised lipids compared with non-oxidisedlipids in Acuvue lenses. There was an increase of ~50% in binding ofmildly oxidised lipids in PureVision lenses. If the lipids werestrongly oxidised then they bound less than non-oxidised lipids inboth contact lens types.Conclusions: There are differences in the ability of different contactlenses to bind oxidised lipids. It appears that mildly oxidised lipids,such as might occur in vivo can bind more strongly to some types ofcontact lenses than others. This experimental procedure provides aplatform for testing the ability of multi-purpose cleaning solutions toremove oxidised lipids.Commercial Relationships: Thomas J. Millar, Alcon (F), Allergan(F); Burkhardt S. Schuett, Alcon (F), Allergan (S)Support: AlconProgram Number: 499 Poster Board Number: B0136Presentation Time: 10:30 AM - 12:15 PMIn-Vivo Wettability of Contact Lenses Worn in a Low HumidityEnvironmental Exposure Chamber (LH-EEC) Show ComparableChanges to Traditional Field TrialsFiona Soong 1 , Jalaiah P. Varikooty 2 , Nancy J. Keir 2 , Lyndon W.Jones 2 , Piyush Patel 1 . 1 R & D, Inflamax Ressearch, Toronto, ON,Canada; 2 CCLR, University of Waterloo, Waterloo, ON, Canada.Purpose: The LH-EEC is a natural provocation research model,which tightly controls environmental variables (humidity;temperature; air flow) and is a valuable tool to study dry eye, withlittle information on its utility to evaluate contact lens (CL) wear. Thepurpose of this study was to use the LH-EEC model to observe invivoCL wettability changes and to compare these results with thosereported in typical CL field studies.Methods: Ten symptomatic CL wearers were randomized and fitwith 1-day Acuvue® Moist® (etafilcon A): CLA in one eye and 1-Day Acuvue® TruEye (narafilcon A): CLB in the contralateraleye. They were exposed to LH-EEC for 180 mins with instruction towatch a movie screen. Following CL insertion, 3 consecutivemeasures of tear osmolarity were taken with TearLab® prior to LH-EEC entry and exit. Dryness symptoms were rated from 0 (nodiscomfort) to 4 (constant discomfort), and were collected atspecified intervals throughout the chamber visit as were observationsof blink rate (#blinks/min). In-vivo wettability was graded using a 0(excellent) to 4 (extremely poor) scale with 0.25 steps.Results: After only 180 mins in the LH-EEC, there was trend ofincreasing tear osmolarity for both CLA (7.4±3.6mOsmol) and CLB(4.80±3.23mOsmol), but this was not significant (p>0.05). Drynesssymptom scores showed non-significant increase from pre to postchamber for CLA (+1.10±0.53) but a significant (p=0.001) increasefor CLB (+1.40±0.31). Blink rate significantly increased (p
ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneafrom pre-EEC rates of 42.0±4.8 blinks/min to average maximum of61.2±4.3 blinks/min. Lens wettability worsened significantly overtime for both CLA and CLB 0.58±0.18 (p=0.01) and 0.65±0.25(p=0.03) respectively. These values are comparable to changes inwettability seen after 8 hrs of wear with both study materials(Luensmann et al; Keir et al.)Conclusions: The LH-EEC exacerbates ocular symptoms and signsafter 180 mins with CL wear. Significant changes in lens wettabilitywere seen during the exposure and yielded values comparable toresults shown in traditional trials with 8 hrs of lens wear. The LH-EEC provides a way to accelerate extended day CL wear andprovides noteworthy research options for a controlled provocationstudy of CL and dry eye signs and symptoms in a shorter time course.Commercial Relationships: Fiona Soong, Inflamax Research (C);Jalaiah P. Varikooty, Alcon (F); Nancy J. Keir, TearScience (F),Alcon (F), Alcon (R), Allergan (F), Johnson & Johnson (F),CooperVision (F), Visioneering, Inc. (F); Lyndon W. Jones, Alcon(F), Alcon (R), Allergan (F), Abbott Medical Optics (R), Bausch &Lomb (R), Ciba Vision (F), Ciba Vision (R), CooperVision (F),Johnson & Johnson (F), Johnson & Johnson (R); Piyush Patel,Inflamax Research (E)Program Number: 500 Poster Board Number: B0137Presentation Time: 10:30 AM - 12:15 PMViscoelasticity and mesh-size at the surface of hydrogelscharacterized with microrheologyThomas E. Angelini, Ryan M. Nixon, Alison C. Dunn, Juan M.Uruena, John Pruitt, W G. Sawyer. MAE, University of Florida,Gainesville, FL.Purpose: Delefilcon A contact lenses contain a water gradientstructure that transitions from a low water content silicone hydrogelcore to a high water content surface gel. This work explores theproperties of the high water content surface gel, designed to mimicthe physical properties of the corneal surface, improving contact lenscomfort. The ~6 µm thick gels have an average water content thatexceeds 80%, yet the properties of the outer layer that makes directcontact with the eye are not known. This study examines the elasticand viscous moduli at the outermost surface of these soft gels tounderstand the physical interactions between contact lenses and theeye.Methods: Microrheological tests were performed on the surfaces of astandard silicone hydrogel (balafilcon A) and on water gradientcontact lenses (delefilcon A). Microspheres (0.5 micron radius) weresandwiched between 3mm sections of lens material and kept indeionized water. Video microscopy was performed at 90xmagnification, and the beads were tracked using digital imageanalysis software.Results: The mean-squared-displacement (MSD) was computed foreach particle, and averaged (N=32 for nelfilcon A; N=80 forbalafilcon A). Beads embedded in the surface gel layer of delefilconA exhibited significant motion, displacing between 50 to 100nm overtimescales below two seconds. By contrast, no detectable beadmotion above the noise threshold was observed in the balafilcon Asystem; beads moved only 10nm to 16nm over the same two secondperiod. We compute the frequency-dependent elastic and viscousmoduli, G’ and G’’ from the MSD measurement. We find moduliwith very weak frequency dependence between 10 and 100 radiansper second, and an elastic modulus that varies between 0.3 and 1 Pa.Thus, from elasticity theory of cross-linked flexible polymers, weestimate that the water content at the outermost region of thedelefilcon A surface gel layer is above 99%.Conclusions: Surface gel layers on contact lenses possess afrequency dependence similar to low concentration polymer gels.Remarkably, the modulus at the outermost surface is over 1000 timeslower than the mean elastic modulus of the entire surface gel layer.This large modulus change, however, only requires roughly 15%reduction in polymer concentration. This suggests that the polymerconcentration marginally drops near the surface as polymer chainsand crosslinks become sparse.Commercial Relationships: Thomas E. Angelini, alcon (F); RyanM. Nixon, Alcon (F); Alison C. Dunn, Alcon (F); Juan M. Uruena,Alcon (F); John Pruitt, Alcon (E); W G. Sawyer, Alcon (F)Program Number: 501 Poster Board Number: B0138Presentation Time: 10:30 AM - 12:15 PMIn vitro Uptake and Release of Natamycin Dex-b-PLANanoparticles from Silicone Hydrogel Contact Lens MaterialsChau-Minh Phan 1 , Lakshman N. Subbaraman 1 , Lyndon W. Jones 1 ,Shengyan Liu 2 , Frank Gu 2 . 1 Centre for Contact Lens Research,School of Optometry and Vision Science, University of Waterloo,Waterloo, ON, Canada; 2 Department of Chemical Engineering,University of Waterloo, Waterloo, ON, Canada.Purpose: To evaluate the uptake and release of the antifungal agentnatamycin encapsulated within poly(D,L-lactide)-dextrannanoparticles (Dex-b-PLA NPs) from model silicone hydrogelcontact lens materials.Methods: Six model contact lens materials (gel A:poly(hydroxyethyl methacrylate, pHEMA); gel B: 85% pHEMA:15% [Tris(trimethylsiloxy)silyl]-propyl methacrylate (TRIS); gel C:75% pHEMA: 25% TRIS; gel D: 85% N,N dimethylacrylamide(DMAA): 15% TRIS; gel E: 75% DMAA: 25% TRIS; gel F:DMAA) were prepared using photoinitiation. The resulting lensmaterials were incubated in two conditions: (1) natamycin dissolvedin deionized (DI) water, and (2) natamycin encapsulated within Dexb-PLANPs in 9.1 % dimethylsulfoxide (DMSO)/DI water for 7 days(d) at 25±3 oC. The release of natamycin from these materials in 2mL of unpreserved saline solution, pH 7.4 at 32±2 oC was monitoredusing UV-Visible spectrophotometry at 304 nm over 7 d. The releasesolution was replenished every 24 hours (h).Results: The uptake of natamycin by all model lens materialsincreased between 1 and 7 d (p
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