The Parasitic Ulcer Treatment Trial (PUTT) is a multi-center, parallel-group, randomized clinical trial. The purpose of this study is to determine whether including topical corticosteroids in a regimen for acanthamoeba keratitis (AK) will improve vision. Patients presenting to all enrollment centers with evidence of acanthamoeba keratitis will be eligible for the trial if there is evidence of ocular inflammation after 4 weeks of anti-amoebic therapy. Those who agree to participate will be randomized to one of two treatment groups: * Group 1: Topical corticosteroid * Group 2: Topical placebo