Management of Adenoviral Keratoconjunctivitis: Challenges and Solutions

Labib, Bisant A; Minhas, Bhawanjot K; Chigbu, DeGaulle I

Though molecular iodine has long been established as an effective antiseptic agent, its formidable toxicity upon DovePress contact to mucosal surfaces deterred it for use in clinical the clinical setting. 30 However, combining iodine with povidone allowed for this antiseptic to be safely and routinely used in the ophthalmic setting, and has even shown promise in the management of EKC affected individuals. Povidone-iodine (PVI) is a broad-spectrum microbicide solution, which exists in multiple forms that are easily accessible, and a cost-effective disinfectant agent. Since its discovery, it has been routinely utilized in the medical field as an antiseptic agent for laboratory and surgical purposes. Furthermore, it has found much purpose in the ophthalmic setting as an effective disinfecting solution due to its proven toxicity against viruses, bacteria, parasites, fungi, yeasts, molds, and protozoans. 31 Diluted forms of PVI are commercially sold as Betadine (Alcon Laboratories, Inc., Fort Worth, TX 76134) in 5% and 10% concentrations and can be further weakened as medical use requires. It is critical to note that, unlike other antiseptics, PVI does not lose antimicrobial activity with decreased available iodine concentration in solution when a diluent is added. 30 The mode of action requires the oxidation of pathogen nucleotides, amino acids, and proteins, damaging vital bacterial cellular mechanisms. 32 Additionally, in vitro investigation indicates that PVI impedes the host's inflammatory response to a viral pathogen by affecting both host and pathogen parameters. 33 This may give insight into how inoffice PVI irrigation may alleviate inflammatory symptoms associated with EKC. Specific pathogen consequences include inhibition of production and release of exotoxins (such as α-hemolysin, phospholipase C, and lipase) and suppression of bacterial enzymes (such as elastase and ßglucuronidase). 32 Host factors involve modulation of antioxidant and free radical activity, inhibition of inflammatory effector cells and mediators (such as TNF-α and ß-galactosidase), inhibiting matrix metalloproteinase production, and enhancing healing signals via activation of T cells and macrophages. 32 Globally, PVI characteristics that make it ideal for clinical use include broad antimicrobial spectrum, lack of resistance, ability to penetrate biofilms, low cytotoxicity, suitable tolerability, and overall favorable risk/benefit profile. 32 Such versatility, ease of access, and ubiquitous use in antisepsis have been further promoted by biochemical characteristics of the compound. The combination of a synthetic carrier homopolymer (2-pyrrolidnone, 1-ethenyl-), which has no innate germicidal ability, and iodine forms PVI. 34 In aqueous form, free iodine is released into solution from the PVI complex, which is what provides the microbicidal activity. 32 Studies have shown that PVI exhibits antimicrobial activity proportional to the concentration of free iodine released in any given solution of specified dilution, regardless of PVI concentration. 30 In addition to its welldocumented antimicrobial activity, a study examining the virucidal efficacy of 0.01%, 0.1%, 1%, and 10% PVI demonstrated that 0.1% solution was actually the most effective against HAdV 3, as it maximized free iodine concentration. 30 Specifically, PVI formulations have been proven effective against non-enveloped human viruses including HAdV, although, it has been postulated to be adenoviral type d