Intravitreal Injections and Endophthalmitis

Stephen J. Kim, MD

Disclosures

Int Ophthalmol Clin. 2015;55(2):1-10. 

In This Article

Povidone-iodine

The most common agent used to reduce ocular flora is povidone-iodine. Povidone-iodine or pyrrolidone-iodine is an iodophor (carries iodine in a complexed form so free iodine concentration is low) and potent antiseptic that provides rapid and broad-spectrum bactericidal properties. Compared with similar compounds, povidone-iodine is highly soluble and less toxic. Povidone-iodine is a loose complex of elemental iodine with a neutral amphipathic organic compound poly vinyl pyrrolidone, which serves as a sustained release reservoir of iodine. The disinfecting characteristics of iodine arise from its ability to substitute for covalently bound hydrogens and the antimicrobial action of povidone-iodine can almost be entirely attributed to free molecular iodine, which reacts in electrophilic reactions with enzymes of the respiratory chain as well as amino acids from the cell membrane proteins located in the cell wall. Consequently, povidone-iodine has a nonselective mechanism of action and no cases of resistance have been reported to date. In vitro studies demonstrate rapid bactericidal effects upon contact against common conjunctival bacterial flora with elimination times ranging from 30 to 180 seconds.[11] Despite the absence of direct clinical evidence that povidone-iodine prevents or reduces endophthalmitis after IVT injection, rationale for its benefit is extrapolated from a prospective trial that demonstrated a reduced rate of endophthalmitis after cataract surgery.[12] Moreover, prospective studies have consistently shown significant reduction of positive bacteria cultures after topical application of 5% povidone-iodine in eyes undergoing IVT injection.[13] Equally as important, povidone-iodine is inexpensive, readily obtained, and safe.[3] Adverse reactions are usually limited to irritation or localized allergic reaction and no cases of anaphylaxis related to its ophthalmic use have been reported.

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