Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneaapproaches. In the absence of DPPC, clean contact lenses were highlyhydrophilic and resisted dewetting, whereas when soaked overnightin 1 mg/ml lysozyme showed substantial dewetting. Standarddeviation across 4 samples was about 10%. In the presence of DPPC,dewetting is stabilized on the lysozyme adsorbed contact lens surface.For clean lenses, a 200% step-strain produces a low force responseindicating no attachment of cells to the lens substrate. Whereas forcontact lens soaked overnight in 1 mg/ml lysozyme solution, a highermaximum force is exhibited, indicating relatively greater celladhesion to the contact lens. This stress relaxes quickly to a newequilibrium value, likely due to the re-organization and relaxation ofthe adhered corneal cells.Conclusions: Our findings show that adsorbed lysozyme decreasesthe hydrophilicity of the lens surface leading to dewetting. Depositionof lysozyme also makes the lens surface more attractive to celladhesion.Fig1: Normalized wet area as a function of time with standarddeviation of 4 samples, for pure and lysozyme adsorbed contactlenses.Fig2: Step-strain data for uncoated and lysozyme coated contact lenswith corneal epithelial cells.Commercial Relationships: Saad Bhamla, None; Claire M.Elkins, None; David Bergsman, None; Gerald G. Fuller, NoneProgram Number: 489 Poster Board Number: B0126Presentation Time: 10:30 AM - 12:15 PMSecretory Phospholipase A2 Type IIA Levels across the WearCycle: Response to Lens Age or Indication of CL IntoleranceWalter L. Nash, Alan Landers, Manal M. Gabriel, Jennifer D. Lane,Michael S. Foster. Vision Care, Alcon, Duluth, GA.Purpose: To evaluate the difference in day one versus day twentyeightlevels of secretory phospholipase A2 Type IIA (sPLA2IIA) inthe tear envelope of symptomatic (decline in comfort over wearcycle) and asymptomatic subjects.Methods: Lenses were collected from subjects aseptically and storedat below -20 degrees C. Subjects wore the same non-ionic siliconehydrogel lens material and used the same lens care regimen. Lenseswere equilibrated to ambient temperature and rinsed in 2 mL ofphosphate buffered saline for 5 minutes with agitation. The rinsatewas subjected to a sandwich ELISA using a monoclonal antibodyspecific for sPLA2IIA. The plate was washed and anAcetylcholinesterase (ACHe); Fab’conjugate was added to the platewhich selectively binds to a different epitope on the sPLA2IIAmolecule. Finally, the enzymatic activity of ACHe was measured byadding a reagent containing the ACHe substrate and reading the plateat a wavelength of 420 nm by spectrophotometry.Results: Symptomatic and asymptomatic subjects exhibited similarlevels of sPLA2IIA at day 1 as on day 28; with symptomatic subjectsexhibiting 17.2±6.2 and 17.8±8.9 ng/lens sPLA2IIA, respectively,and asymptomatic subjects exhibiting 21.7±5.6 and 24.6±9.2 ng/lenssPLA2IIA, respectively. Comparing the amount sPLA2IIA in the tearenvelope between symptomatic and asymptomatic subjects on bothday 1 and day 28 showed no statistical differences using nonparametricMann-Whitney analysis.Conclusions: sPLA2IIA hydrolyzes fatty acids generating freearachidonic acid and lysophospholipids, the precursors of proinflammatorylipid mediators. Studies have reported elevated levelsof sPLA2IIA in the tears of intolerant contact lens wearers. Thisstudy demonstrates no changes in the level of sPLA2IIA in the tearenvelope over the course of the wear cycle in symptomatic orasymptomatic lens wearers. Our findings, suggest that the mechanismdriving comfort at the time of lens replacement may not be the sameas the mechanism driving contact lens intolerance as described in theliterature.Commercial Relationships: Walter L. Nash, ALCON, a NovartisCompany (E); Alan Landers, Alcon (E); Manal M. Gabriel, Alcon,A Novartis company (E); Jennifer D. Lane, Alcon Laboratories (E),Novartis (E); Michael S. Foster, Alcon, a Novartis Company (E)Program Number: 490 Poster Board Number: B0127Presentation Time: 10:30 AM - 12:15 PMCharacterization of contact lenses through oxygen permeability,equilibrium water content, and silicone contentScott Curtin, Michelle Seitz, Meng Ouyang, Katarina Tomic,Meredith Wiseman, Hanny Vanwersch. DSM, Berkeley, CA.Purpose: In an effort to contribute to the growing knowledge base ofmaterials properties of silicone hydrogel (“SiHy”) contact lenses andimprove material design for formulation, DSM has evaluated threeprincipal material parameters that affect oxygen permeability (Dk);amount of silicone component present, intrinsic permeability ofsilicone component, and connectivity of silicone-containing phaseMethods: The coulometric oxygen permeability (Dk) andequilibrium water content (EWC) of commercial SiHy contact lenseswere measured at DSM using methods described in ISO 18369-4:2006 and ANSI Z80.20-2010. A modified Mocon MH 2/21 wasused to measure the oxygen permeability for 5 contact lenses usingCIBA Vision O2 Optix for the Q value. The silicon and fluorinecontents of dried commercial lenses were measured by X-rayfluorescence to approximately ± 0.5 wt%.Results: CIBA Vision Air Optix 108±3.3 (110), CIBA Vision DailiesTotal One 131±4.3 (140), Acuvue Oasys 105±1.6 (105), AcuvueTrueye 114±2.1 (110), Coopervision Biofinity 128±6.1(128) withmanufacturer-claimed values in parentheses and all lenses besidesCIBA Vision lenses were reported using polarographic method . Awet blot gravimetric method was used to measure EWC for six lenseswith measured values closely matching reported values. CIBA VisionAir Optix 32.7±0.5% (33%), CIBA Vision Dailies Total One29.9±0.8% (33%), Acuvue Oasys 37.3±0% (38%), Acuvue Trueye44.5±0.4% (46%), Coopervision Biofinity 46.3±0.8% (48%), andCIBA Vision O2 Optix 30.5±0.5% (33%). Additionally, the atomicsilicon and fluorine contents of the dried lenses were measured with©2013, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. 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