Acanthamoeba KeratitisPhase 3PUTTNCT06213649
Parasitic Ulcer Treatment Trial
A Phase 3 study testing Polyhexamethylene biguanide (PHMB) and Topical corticosteroid in people with Acanthamoeba Keratitis, run by Jeremy Keenan, MD, MPH at 22 sites in 4 countries.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 8 years and older
- Conditions the study is for
- Acanthamoeba Keratitis
- What is being tested?
- Polyhexamethylene biguanide (PHMB) and Topical corticosteroid
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 232 participants
- Where
- 22 sitesin 4 countries
- Study dates
- 1 Jul 2024to Jul 2029
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 8 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
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- No light perception in the affected eye
- Known hypertensive response to steroids
- Corticosteroid allergy
- Concurrent treatment with systemic corticosteroids
- Concurrent granulomatous amoebic encephalitis
Trial locations and contacts
22 sites in 4 countries. Contact the study team or a site near you to ask about taking part.
Krisi Aromin contact
22 sites in 4 countries
United States18 sites, 17 recruiting
- Recruiting
University of Colorado Anschutz
Aurora, Colorado, 80045
Travis Redd, 7208482020, travis.redd@cuanschutz.edu
- Recruiting
Johns Hopkins University
Baltimore, Maryland, 21287
Nakul Shekhawat
- Recruiting
University of Illinois, Chicago
Chicago, Illinois, 60612
Elmer Tu
- Recruiting
University of Florida
Gainesville, Florida, 32605
Sonal Tuli
- Recruiting
Baylor College of Medicine
Houston, Texas, 77030
Alejandro Arboleda, MD MS, 713-798-5143, alejandro.arboleda@bcm.edu
- Recruiting
University of Iowa
Iowa City, Iowa, 52242
Mark Greiner
- Recruiting
University of California Irvine
Irvine, California, 92617
Olivia Lee
- Not yet recruiting
University of California Los Angeles
Los Angeles, California, 90095
Anthony Aldave
- Recruiting
University of Miami
Miami, Florida, 33136
Guillermo Amescua
- Recruiting
New York Eye and Ear Infirmary
New York, New York, 10003
Sumayya Ahmad
- Recruiting
Columbia University
New York, New York, 10032
Leejee Suh
- Recruiting
University of South Florida
Orlando, Florida, 33612
Edgar Espana
- Recruiting
University of Pennsylvania
Philadelphia, Pennsylvania, 19104
Bennie Jeng
- Recruiting
University of Pittsburgh Medical Center
Pittsburgh, Pennsylvania, 15219
Gaurav Prakash, MD, 412-647-2200, prakashg@upmc.edu
- Recruiting
Devers Eye Institute
Portland, Oregon, 97210
Ashlin Joye
- Terminated
Oregon Health and Science University
Portland, Oregon, 97239
- Recruiting
University of California, San Francisco
San Francisco, California, 94158
Krisianne Aromin, krisianne.aromin@ucsf.edu
Jeremy Keenan, MD, MPH
- Recruiting
University of Washington
Seattle, Washington, 98104
Minh Nguyen, MD, 206-543-7250, minhng88@uw.edu
India2 sites, 2 recruiting
- Recruiting
Aravind Eye Hospital
Coimbatore, Tamil Nadu
Revathi Rajamaran
- Recruiting
Aravind Eye Hospital
Madurai, Tamil Nadu
NV Prajna
Brazil1 site, 1 recruiting
- Recruiting
Federal University of São Paulo
São Paulo
Denise de Freitas
United Kingdom1 site, 1 recruiting
- Recruiting
Moorfields Eye Hospital
London
Su-yin Koay
About this study
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
- Conditions
- Acanthamoeba Keratitis
- Being tested
- Polyhexamethylene biguanide (PHMB), Topical corticosteroid, Topical placebo
- Keywords
- corneal ulcer, steroids
- Medical subject headings
- Acanthamoeba Keratitis, Corneal Ulcer
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Polyhexamethylene biguanide (PHMB)Drug
Also called Polyhexanide
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.
Topical corticosteroidDrug
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.
Topical placeboOther
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.
| Study group | Role | What they receive |
|---|---|---|
| Topical steroids | Experimental | Participants in this arm will receive anti-amoebic therapy plus topical steroids. Receives: Drug: Polyhexamethylene biguanide (PHMB); Drug: Topical corticosteroid |
| Topical placebo | Placebo comparator | Participants in this arm will receive anti-amoebic therapy plus topical placebo. Receives: Drug: Polyhexamethylene biguanide (PHMB); Other: Topical placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Vision
Best corrected visual acuity
Measured: 6 Months
Secondary outcomes (3)
Self-reported eye pain
Pain scale (Likert 11-point ordinal scale from 0 to 10; 0=no pain, 10=worst pain)
Measured: 2 months
Clinical Resolution
Time until clinical resolution (i.e., healed ocular surface and absence of inflammation)
Measured: 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
Measured: 6 Months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Jan 2024
- Study start1 Jul 2024
- Primary completionJul 2029 (estimated)
- Study completionJul 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Acanthamoeba KeratitisStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 232 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Jeremy Keenan, MD, MPH
- Sponsor type
- University, hospital or other
- Collaborators
- Johns Hopkins University, Oregon Health and Science University, University of Illinois 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
- Responsible party
- Sponsor-investigator, Jeremy Keenan, MD, MPH, University of California, San Francisco
- Investigators
- Jeremy Keenan, MD, MPH, Principal investigator, Proctor Foundation, UCSFGerami Seitzman, MD, Principal investigator, Proctor Foundation, UCSF
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06213649
- Sponsor's protocol ID
- 23-39559
- Other IDs
- UG1EY033284
- Acronym
- PUTT
- Status last verified
- Apr 2026
- First submitted
- 9 Jan 2024
- Last updated
- 1 Oct 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: IPD available on request.
Study at a glance
From the registry record, last updated by the sponsor on 1 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Parasitic Ulcer Treatment Trial
- ClinicalTrials.gov ID
- NCT06213649
- Acronym / sponsor ID
- PUTT / 23-39559
- Conditions
- Acanthamoeba Keratitis
- Keywords
- corneal ulcer, steroids
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 232 participants (estimated)
- Lead sponsor
- Jeremy Keenan, MD, MPHUniversity, hospital or other
- Collaborators
- Johns Hopkins University, Oregon Health and Science University, University of Illinois 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
- Study start
- 1 Jul 2024 (actual)
- Primary completion
- Jul 2029 (estimated)
- Study completion
- Jul 2029 (estimated)
- First posted
- 19 Jan 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Topical steroids | Experimental | Drug: Polyhexamethylene biguanide (PHMB), Drug: Topical corticosteroidParticipants in this arm will receive anti-amoebic therapy plus topical steroids. |
| Topical placebo | Placebo comparator | Drug: Polyhexamethylene biguanide (PHMB), Other: Topical placeboParticipants in this arm will receive anti-amoebic therapy plus topical placebo. |
Who may qualify
- Ages
- 8 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (2 listed)
- 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
Key exclusion criteria (11 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Polyhexamethylene biguanide (PHMB)Also: PolyhexanidePHMB 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 placebo, Topical steroids |
| Topical corticosteroidDexamethasone 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. | Drug | Topical steroids |
| Topical placeboAn 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. | Other | Topical placebo |
Primary outcome
Vision
Time frame: 6 Months
Best corrected visual acuity
3 secondary outcomes
Self-reported eye pain
Time frame: 2 months
Clinical Resolution
Time frame: 12 months
Multivariate Analysis
Time frame: 6 Months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Oct 2026.
- Individual participant dataSharing planned: Yes. IPD available on request.
Related trials for Acanthamoeba Keratitis
Not yet recruitingObservational study
Evaluation of Resveratrol and Its Loaded Nanoparticles on Acanthamoeba
Corneal Ulcer Caused by Acanthamoeba
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Krisi Aromin contact
Jeremy Keenan, MD, MPH principal investigator
Proctor Foundation, UCSF
Gerami Seitzman, MD principal investigator
Proctor Foundation, UCSF
22 sites in 4 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Polyhexamethylene biguanide (PHMB) and Topical corticosteroid in people with Acanthamoeba Keratitis, run by Jeremy Keenan, MD, MPH at 22 sites in 4 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 1 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 22 sites in United States, India, Brazil, United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Jeremy Keenan, MD, MPH (415-476-6323, jeremy.keenan@ucsf.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Vision (time frame: 6 Months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Oct 2026.