Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneafound in contact lens cases of Polyquaternium/Aldox care systemscan adhere to contact lenses in relatively high numbers. This mayfacilitate their transfer into the eye and the production of cornealinfiltrates.Commercial Relationships: Ajay Kumar Vijay, Bausch+Lomb(F); Mark D. Willcox, Allergan Inc (C), Allergan Inc (R), BrienHolden Vision Institute (P), Bausch + Lomb (C), Basuch + Lomb (R)Program Number: 507 Poster Board Number: B0144Presentation Time: 10:30 AM - 12:15 PMAntimicrobial Activity of Melimine or Cathelicidin Bound toContact LensesDebarun Dutta 1, 2 , Mark D. Willcox 2 . 1 Brien Holden Vision Institute,Sydney, NSW, Australia; 2 School of Optometry and Vision Science,University of New South Wales, Sydney, NSW, Australia.Purpose: Development of antimicrobial contact lens could have thecapacity to reduce the rate of contact lens related adverse events. Thepurpose of this study was to evaluate two cationic peptides coated oncontact lenses for their activity against P. aeruginosa and S. aureus.Methods: Minimal inhibitory concentration (MIC) of two peptides,Melimine (a synthetic peptide) and Cathelicidin (LL37) wasmeasured against strains of P. aeruginosa and S. aureus. Increasingconcentrations of peptides were covalently bound to contact lenses.Antimicrobial activity against the bacteria was evaluated bymeasuring the amount of cell death compared to control lenses withno melimine or LL37.Results: MIC of LL37 against both P. aeruginosa and S. aureus was3.9µg ml -1 , whereas for Melimine against the same bacteria it was500 µg ml -1 and 250 μg ml -1 respectively. Contact lenses covalentlyreacted with 1mg ml -1 Melimine showed 0.8 log and 2.6 loginhibition against P. aeruginosa and S. aureus respectively whereasno inhibition was detected with LL37 at that concentration. Contactlenses prepared with 3mg ml -1 melimine and LL37 showed 3.1 logand 3.3 log inhibition against P. aeruginosa , 3.9 log and -0.2 loginhibition against S. aureus respectively.Conclusions: Whilst Melimine on contact lenses had activity againstboth bacterial types; covalently bound LL37 was not active against S.aureus. These differences suggest different mechanisms of actionagainst Gram-negative or Gram-positive bacteria by these twocationic peptides.Commercial Relationships: Debarun Dutta, None; Mark D.Willcox, Allergan Inc (C), Allergan Inc (R), Brien Holden VisionInstitute (P), Bausch + Lomb (C), Basuch + Lomb (R)Program Number: 508 Poster Board Number: B0145Presentation Time: 10:30 AM - 12:15 PMEstablishing a standard method for evaluating efficacy againstAcanthamoebaMonica Crary, Rhonda Walters, John Bartell, Manal M. Gabriel,Jagath Kadurugamuwa, Bradley J. Catalone. Alcon Laboratories,Fort Worth, TX.Purpose: To establish a standard method for Multipurpose ContactLens Solution (MPS) efficacy testing against Acanthamoeba byidentifying and reducing variables.Methods: Bacterized and axenic cultures of trophozoites were usedto determine if culture methods affected MPS efficacy. Cysts thatwere prepared by starvation with or without Escherichia coli weretested to determine variability in susceptibility to MPS followingbacterization. Additionally, the effect of heterogeneous cultures onMPS efficacy was determined by examining the increasing ratios ofcysts to trophozoites in axenic cultures that were harvested between3-7 days of age. Most Probable Number was used for enumeration atdifferent post-test time points to determine the earliest appropriateread date for both cell types. Other variables such as inoculumconcentrations and MPS volumes were also examined.Results: Current recommendations suggest that bacterization ofAcanthamoeba is the preferred culture method when evaluating MPSefficacy. However, residual E. coli decreases the available biocide,thereby resulting in variability correlated with bacterialconcentration. Current culture methods are limited in their ability togenerate homogeneous populations of trophozoites. Axenictrophozoite cultures can contain cysts which contribute to theobserved variability of MPS efficacy. Harvesting of trophozoites at 3days results in a more homogenous population of trophozoites ascompared to harvesting at 5 or 7 days. Another variable thatcontributes to conflicting results in the literature is the duration ofincubation prior to enumeration. These studies clearly demonstratethat the minimum incubation period for trophozoites plates is 7 days,whereas for cysts it is 14 days. Earlier time points result in incorrectenumeration. Other potential sources of variability include surface tovolume ratio of organisms and MPS.Conclusions: The maximization of a homogenous population oftrophozoites or cysts is necessary to obtain reproducible results whentesting MPS efficacy. Variability of test results is affected by thepurity of the target cell type. For maximum accuracy, enumeration ofcells should not be performed prior to the minimum incubationperiod. These identified variables have a significant effect on thereproducibility and the performance of MPS against Acanthamoeba.Commercial Relationships: Monica Crary, Alcon Labs (E);Rhonda Walters, Alcon Laboratories (E); John Bartell, Alcon Labs(E); Manal M. Gabriel, Alcon, A Novartis company (E); JagathKadurugamuwa, Alcon Labs (E); Bradley J. Catalone, Alcon, aNovartis Company (E)Program Number: 509 Poster Board Number: B0146Presentation Time: 10:30 AM - 12:15 PMRisk Factors for Contact Lens Related Microbial Keratitis inSingaporeChris Lim 1 , Nicole A. Carnt 1, 2 , Mohamed Farook 3 , Janice Lam 3 ,Jodhbir S. Mehta 3 , Donald T. Tan 3 , Fiona Stapleton 1 . 1 School ofOptometry and Vision Science, University of New South Wales,Sydney, NSW, Australia; 2 Moorfields Eye Hospital Trust, London,United Kingdom; 3 Singapore National Eye Centre, Singapore,Singapore.Purpose: Patterns of contact lens prescribing, wearer behavior andenvironmental microbiota vary across different cultures and climates,which may impact risks for microbial keratitis. This studyinvestigates independent risk factors for microbial keratitis in contactlens wearers in Singapore.Methods: Cases were contact lens wearers presenting to SingaporeNational Eye Centre with microbial keratitis between 2009-2010.Contact lens wearers attending for routine aftercare at a nearbyUniversity Clinic over the same time period were identified ascontrols. All wearers completed a previously validated questionnairedescribing contact lens wear history, hygiene and compliance habitsand demographics. Risk factors significant in univariate analysis(p