ABSTRACT The aim of this study was to determine the antiamoebic efficacy of povidone-iodine when used as an adjunct to topical biguanide therapy for Acanthamoeba keratitis. Patients with smear- or culture-positive Acanthamoeba keratitis received topical chlorhexidine 0.04%, half-hourly for 2 days, then hourly for days 3–6, then eight times per day for days 7–28. Participants were randomized in a 1:1 ratio to receive either adjunctive topical povidone-iodine at the same frequency as chlorhexidine or no additional therapy (i.e., control group). Povidone-iodine was initially administered as a 2.5% solution but was reduced to a 1% solution after several reports of intolerance. The primary outcome was Acanthamoeba growth from the culture of corneal scrapings at 1, 2, and 4 weeks after randomization, as assessed by laboratory staff masked to treatment allocation. Of 49 patients enrolled, 25 were randomized to adjunctive povidone-iodine (mean age 48 SD 16 years; 32% female) and 24 to control (mean age 43 15 years; 33% female). Four (16%) participants discontinued 2.5% povidone-iodine prematurely due to intolerance. The proportion of participants with a positive culture during the initial 4 weeks of antiamoebic treatment was not significantly different in the povidone-iodine group (6/18 33% at 4 weeks) and control group (5/16 31% at 4 weeks) (RR 0.90, 95%CI: 0.35–2.29; P = 0.82). When used as an adjunctive to standard biguanide therapy, povidone-iodine did not markedly accelerate the clearance of Acanthamoeba organisms from the corneal surface over the initial month of therapy. This study is registered with ClinicalTrials.gov as NCT03484507 .
Rajaraman et al. (Tue,) studied this question.