A Phase 3 interventional study of Polyhexamethylene biguanide (PHMB) and Topical corticosteroid in Acanthamoeba Keratitis, sponsored by Jeremy Keenan, MD, MPH. Recruiting at 22 sites in 4 countries. Open to participants aged 8 Years and older. Per ClinicalTrials.gov, last updated 2026-10-01.
Sponsored by Jeremy Keenan, MD, MPH · Phase 3, Interventional, and Treatment
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:
63 studies on the registry are indexed under Corneal Ulcer; 8 are open to participants now.
This study's planned enrollment of 232 is above the median of 60 across 45 interventional studies indexed under Corneal Ulcer.
Browse Corneal Ulcer studies →This is the only study on the registry with Jeremy Keenan, MD, MPH as lead sponsor.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants in this arm will receive anti-amoebic therapy plus topical steroids.
Drug: Polyhexamethylene biguanide (PHMB) · Drug: Topical corticosteroid
Participants in this arm will receive anti-amoebic therapy plus topical placebo.
Drug: Polyhexamethylene biguanide (PHMB) · Other: Topical placebo
PHMB is a cationic antiseptic agent used for topical treatment of acanthamoeba keratitis (AK). Both treatment groups will take PHMB at least 4 times daily while on the allocated study drug.
Also known as: Polyhexanide
Dexamethasone sodium phosphate, 0.1% ophthalmic solution will be administered 4 times daily for 4 weeks, then 2 times daily for 2 weeks, then 1 time daily for 2 weeks.
An artificial tear ophthalmic solution will be administered 4 times daily for 4 weeks, then 2 times daily for 2 weeks, then 1 time daily for 2 weeks.
Vision
Best corrected visual acuity
Time frame: 6 Months
Self-reported eye pain
Pain scale (Likert 11-point ordinal scale from 0 to 10; 0=no pain, 10=worst pain)
Time frame: 2 months
Clinical Resolution
Time until clinical resolution (i.e., healed ocular surface and absence of inflammation)
Time frame: 12 months
Multivariate Analysis
The multivariate analysis will include the following outcomes measured at 6 months: best corrected visual acuity, corneal thinning on optical coherence tomography (OCT), scar density on Scheimpflug imaging, irregular astigmatism, glare, microbial clearance on confocal microscopy, pain score, time until clinical resolution
Time frame: 6 Months
Not enrolling at this site — choose another above.
Plan to share: Yes — IPD available on request.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
Time frame: After publication of the main results
Access criteria: Request by email addressed to principal investigator.
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Topical Corticosteroid