This is a randomized controlled single blind prospective study evaluating the efficacy of ocular surface sterilization between three different povidone-iodine preparation techniques prior to intravitreal injection. The primary end point is significant different between median colony-forming units pre- and post-sterilization and injection.

Introduction: An estimated 5.9 - 7.9 million intravitreal injections (IVI) were given in 2016. While the incidence of post-injection endophthalmitis is exceedingly low, it is a feared complication of the procedure. 96% of culture-positive post-injection endophthalmitis cases are caused by conjunctival commensals, emphasizing the importance of ocular surface sterilization prior to IVI. The most recently published guidelines for IVI state that "Povidone-Iodine (5-10%) should be the last agent applied to the intended injection site before the injection," a recommendation that is universally followed. However, there is no standard of care regarding the concentration of PI nor the field of sterilization (e.g, cleaning the eyelids and lashes), and technique varies widely in clinical practice. The literature reveals no direct comparison of 5% vs 10% PI in the context of intravitreal injection.

Methods: Single-center randomized prospective trial enrolling patients into three protocols: 5% P-I applied to ocular surface from bottle, 10% P-I swabstick applied to ocular surface, and 10% P-I swabstick applied to lids, lashes, and ocular surface. Pre-procedure cultures will be obtained from the ocular surface, and a second culture will be taken following antisepsis, injection, and irrigation. Standard microbiologic techniques will be used to collect, culture, identify, and quantify ocular surface bacteria counts. Kruskal Wallis test will be used to assess significant difference between median bacterial loads at baseline and post-cleaning, as well as median reduction from baseline. Chi-squared test will be used to assess significant difference between reduction in number of patients with specific bacteria. Following injection, a patient survey will be administered to compare patients' subjective symptoms of ocular surface irritation during the PI preparation phase of the procedure.

Conclusions: The investigators anticipate that no significant difference exists in decrease of median CFUs between the three protocols, and that lower concentration of P-I provides a more comfortable patient experience.

Inclusion Criteria:

• enrollment will be open to men and women of all ethnic backgrounds between the ages of 18-100 who are offered intravitreal injections by Dr. Anthony Mazzulla at his Retina clinic at the Ochsner Clinic Foundation as a treatment for diabetic macular edema, proliferative diabetic retinopathy, age related exudative macular degeneration, or any other cause of choroidal neovascularization or cystoid macular edema.

Exclusion Criteria:

• Current eye infection, actively treated blepharitis, current use of topical or systemic antimicrobial agents, current use of topical or systemic corticosteroids, allergy to iodine, pregnancy, children.