Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Cornealenses, sufficient time must be allowed for the lens to reach a stableposition before assessing the depth of the post-lens fluid reservoir. Ifa lens fit is assessed prematurely, the subsequent lens settling couldgreatly reduce reservoir volume and increase contact with the cornea,and this would limit the value of using these lenses in patients withsevere ocular surface disease.Commercial Relationships: Cherie B. Nau, None; MurielSchornack, NoneSupport: Research to Prevent Blindness and Mayo FoundationProgram Number: 5470 Poster Board Number: A0169Presentation Time: 8:30 AM - 10:15 AMMultivariate Statistical Analysis Examining and Modeling DrugRelease from Contact Lens MaterialsFrances Lasowski, Giuliano Guidi, Heather Sheardown. ChemicalEngineering, McMaster University, Hamilton, ON, Canada.Purpose: Topical administration of eye drops remains the mostprevalent method of delivering drugs to the eye. However significantloss and potential systemic side effects necessitates a more effectivedrug delivery method. Contact lenses represent an attractive option asan alternative vehicle for wide range of therapeutics. Namely, the useof a model contact lens delivery system for the ocular drugs timololmaleate, roscovitine and atropine were investigated. The effects ofdrug loading, material composition and presence of wetting agentswere analyzed to further understand the drug-hydrogel interactionsthat govern release kinetics and critical material properties. However,due to the complex nature of these interactions, single variableanalysis of the data is insufficient to predict of future trends.Methods: Model lens materials were based on combinations ofdimethylacrylamide (DMA), hydroxyethyl methacrylate (HEMA)and methacryloxypropyltris(trimethylsiloxy)silane (TRIS). Thematerials were prepared with and without roscovitine (0.5 wt%),timolol maleate (0.5 wt%) and atropine (0.5 wt% & 1.5 wt%). Otherscontained hyaluronic acid at 0.1 wt%. Release studies wereperformed into PBS solutions using UV- spectroscopy and HPLC toquantify release of each drug. Swelling, extraction and contact anglestudies were done to characterize the materials. This information wascompiled and inputted into ProMV, a multivariate analysis toolprovided by Prosensus, Inc. This allowed for examination by bothPCA (principle component analysis) and PLS (projection to latentstructures).Results: Single variable analysis trends include greater total drugrelease from HEMA/TRIS materials than DMA/TRIS materials,greater release of timolol and atropine than roscovitine, and greaterrelease with HA present. The figure shows sample release kineticsfrom various materials at different drug loadings. Despite thesetrends, it is difficult to see trends bridging all drug loadings andmaterial compositions. With multivariate analysis, it is possible to seethe design space and predict compositions and drugs that yield thepreferred release kinetics and properties.Conclusions: Contact lenses provide a feasible method to deliver avariety of drugs to various ocular tissues. The use of multivariatestatistical analysis provides better modeling and creates a predictivemodel allowing optimization of future materials.Commercial Relationships: Frances Lasowski, None; GiulianoGuidi, None; Heather Sheardown, Alcon (F), Alimera Sciences (F)Support: NSERC 20/20 Ophthalmic Materials NetworkProgram Number: 5471 Poster Board Number: A0170Presentation Time: 8:30 AM - 10:15 AMA study of the feasibility of fitting custom designed contact lensesto guinea pigs, guided by AS-OCT imaging and cornealtopographyYue Liu 1 , Zhi Chen 2 , Christine F. Wildsoet 1 . 1 VIsion Science, Univ ofCA, Berkeley Sch of Optometry, Berkeley, CA; 2 Department ofOphthalmology & Vision Science, Eye & ENT hospital,FudanUniversity, Shanghai, China.Purpose: To examine the efficacy and reliability of anterior segmentOCT (AS-OCT) in guiding specialty contact lens (CL) fitting inguinea pig eyes. Small-scale clinical studies suggesting thatorthokeratology (Ortho-K) is effective in controlling myopiaprogression motivated this study, with our longer term goal being touse the myopic guinea pig model to better understand the mechanismunderlying myopia retardation with Ortho-K.Methods: Six guinea pigs underwent unilateral Ortho-K fitting withtheir contralateral eyes serving as controls. Corneal topography,refraction, biometric axial ocular parameters were assessed to aid inthe design of the Ortho-K lenses; measurements were made everyday, starting on the day of initial lens fitting until the cornealreshaping effect has stabilized. The anterior segment was assessedwith and without fluorescein staining by slit lamp biomicroscopy andphotographically recorded; AS-OCT imaging was used to monitorcorneal integrity, CL stability, and the progress of corneal reshaping.Results: On average, extended wear (EW) Ortho-K lenses couldinduce more than 6 diopters of central corneal flattening andcorresponding paracentral steepening without significantly affectingcorneal integrity and/or the stability of the lens fitting. There was lesscorneal fluorescein staining in the eyes with EW Ortho-K lenses,comparing to the non-lens wearing eye. AS-OCT imagingsignificantly reduced the frequency of lens reordering.Conclusions: The combination of AS-OCT imaging and cornealtopography provided the essential information for designing andfitting Ortho-K lenses to this animal model. The EW OrthoKmodality applied to guinea pig eyes allows for corneal reshapingsimilar to its clinical application. Further study of Ortho-K in thisapplication may yield important insight into the mechanismunderlying its myopia control effect.Commercial Relationships: Yue Liu, Coopervision (F); Zhi Chen,None; Christine F. Wildsoet, NoneSupport: NIH R01 EY12392, UC-Coopervision Discovery GrantProgram Number: 5472 Poster Board Number: A0171Presentation Time: 8:30 AM - 10:15 AMInvestigation of Latanoprost Release from Contact LensMaterials Using in vitro Cell Models©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.