Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneadid not substantially change over the course of the 720 minutes ofmechanical wear. Optical microscopy confirmed that the lenses stillmaintained a surface gel layer.Conclusions: A simple laboratory method for wearing contact lensesthrough mechanical agitation was developed and characterized. Evenafter 720 minutes of simulated wear, the lubricity and surface gellayers were maintained on the delefilcon A lenses.Brennan, AAO 2009.Dunn, et al., Tribology Letters, 2013.Commercial Relationships: Alan Tomlinson, Allergan (E),Allergan (R), Bausch and Lomb (C), TearLab (C), TearLab (I),Alcon, CibaVision (C), Pfizer (R), Pfizer (C); Raied Fagehi, None;Velitchko Manahilov, NoneExperimental Setup for Laboratory Wear Studies.Program Number: 493 Poster Board Number: B0130Presentation Time: 10:30 AM - 12:15 PMLaboratory Model for Wear of Contact Lenses and Effects onLens Lubricity of Surface Gel LayersW G. Sawyer 1 , Juan M. Uruena 1 , Thomas E. Angelini 1 , Alison C.Dunn 1 , John Pruitt 2 . 1 Mechanical and Aerospace Eng, University ofFlorida, Gainesville, FL; 2 Biocompatibility Projects, Alcon VisionCare Research, Johns Creek, GA.Purpose: Lubricity of contact lenses is recognized as an importantcontributor of comfort (Brennan 2009). Experiments aimed atquantifying the lubricity of lenses are traditionally measured on newlenses that have been removed from the package and either gentlyrinsed in a saline solution or tested in the packing solution directly(Dunn 2013). The purpose of this research is to establish a simple andscalable method to mechanically exercise contact lenses and simulatewear in a controlled laboratory environment, and then to performlubricity measurements on the front curve surface of the lenses atvarying time points of wear.Methods: Poly(HEMA) (60% pHEMA) hydrogels were moldedinside of transparent acrylic containers to a thickness ofapproximately 3 mm. A series of poly(HEMA) spheres of 6 mmdiameter were also molded and added to the hydrogel lined cup to apacking fraction of approximately 25%. A single contact lens(delefilcon A) was placed within the ensemble of hydrogel spheresand the container was filled with Phosphate Buffered Saline. Theentire collection was shaken at 31 Hz for various time points. Imageanalysis was used to track the hydrogel spheres and to quantify thecollision frequencies. Based on this analysis a mathematical model ofmechanical energy and tribological severity was developed andcompared to the tribological severity of 1,000 blinks per hour ofwear. Prior to friction testing lenses were examined for evidence ofwear and damage was quantified using scanning optical microscopy.Results: This delefilcon A lenses showed a characteristic frictioncoefficient of mu=0.02, with a standard deviation for eachmeasurement of approximately mu = 0.005. The friction coefficientsPlot of Friction Coefficient versus Simulated Wear Time.Commercial Relationships: W G. Sawyer, Alcon (F); Juan M.Uruena, Alcon (F); Thomas E. Angelini, alcon (F); Alison C.Dunn, Alcon (F); John Pruitt, Alcon (E)Program Number: 494 Poster Board Number: B0131Presentation Time: 10:30 AM - 12:15 PMAssessment of the relationship between contact lens coefficient offriction and subject lens comfortJami R. Kern 1 , Joseph M. Rappon 2 , Erich Bauman 2 , Ben Vaughn 3 .1 Global Medical Affairs, R&D, Alcon, Fort Worth, TX; 2 Vision CareR&D, Alcon, Fort Worth, TX; 3 Biostatistics, Rho, Chapel Hill, NC.Purpose: To examine the relationship between subjective comfortand contact lens coefficient of friction among multiple soft contactlens materials.Methods: A meta-analysis of clinical data (n=157) exploring theassociation between comfort and contact lens lubricity was conductedon 5 soft contact lens materials (delefilcon A, lotrafilcon B,balafilcon A , balafilcon A2, etafilcon A+). Subjective data forinsertion comfort, overall comfort and end of day comfort wereobtained from a database of clinical trials that included studiesconducted between 2004 and 2011. Trials were included in theanalysis unless they met exclusion criteria, including; extended or©2013, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Go to iovs.org to access the version of record. For permissionto reproduce any abstract, contact the ARVO Office at arvo@arvo.org.