NCT06213649 · Jeremy Keenan, MD, MPH
Parasitic Ulcer Treatment Trial
(PUTT)
What this study is about
The Parasitic Ulcer Treatment Trial (PUTT) is a multi-center, parallel-group, randomly assigned clinical trial. The purpose of this study is to determine whether including topical corticosteroids in a regimen for acanthamoeba keratitis (AK) will improve vision.
View original scientific description
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.
Interventions
DRUG
Polyhexamethylene biguanide (PHMB)
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.
DRUG
Topical corticosteroid
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.
OTHER
Topical placebo
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.
Primary outcome measures
Vision
Time frame: 6 Months
Best corrected visual acuity
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- AK on at least one of the following: culture, smear, PCR, shotgun sequencing, biopsy, or confocal microscopy
- Ocular inflammation after 1 month of anti-amoebic treatment, defined as conjunctival, corneal, episcleral, or anterior chamber inflammation
Exclusion criteria
- Evidence or history of interstitial keratitis
- Known herpetic keratitis, as determined from history, exam, or microbiological testing
- Known fungal keratitis, as demonstrated from corneal scrapings
- Corneal perforation or impending corneal perforation
- Prior therapeutic keratoplasty for acanthamoeba keratitis
- Unwillingness or inability to follow-up
- No light perception in the affected eye
- Known hypertensive response to steroids
- Corticosteroid allergy
- Concurrent treatment with systemic corticosteroids
- Concurrent granulomatous amoebic encephalitis
Where
- San Francisco, California
- Aurora, Colorado
- Gainesville, Florida
- Miami, Florida
- Chicago, Illinois
- Iowa City, Iowa
- Baltimore, Maryland
- New York, New York
- Portland, Oregon
- Philadelphia, Pennsylvania
- Pittsburgh, Pennsylvania
- Houston, Texas
And 1 more location — see the full list below.
Collaborators
Johns Hopkins University, Oregon Health and Science University, University of Illinois at Chicago, University of Pittsburgh, University of Pennsylvania, Columbia University, University of Iowa, University of Florida, Aravind Eye Care System, Moorfields Eye Hospital NHS Foundation Trust, Federal University of São Paulo, National Eye Institute (NEI), University of Miami, Baylor College of Medicine, University of Colorado Denver - Anschutz Medical Campus (UCD-AMC)
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 1, 2026 · Source of record for eligibility and locations