AnisometropiaNCT03610997
Photorefractive Keratectomy for Severe Anisometropia and Isoametropia Associated With Amblyopia
A study testing Photorefractive keratectomy in people with Anisometropia and Hyperopia, run by Baylor College of Medicine at 1 site in United States.
Trial summary
Photorefractive keratectomy (PRK) with excimer laser has been used successfully to treat myopia, hyperopia, and astigmatism in adults for over 35 years. Children with high refractive errors that go untreated will develop severe amblyopia. Read more about this study
- Who is it for?
- Ages 2 to 17 years
- Conditions the study is for
- Anisometropia, Hyperopia, High Myopia
- What is being tested?
- Photorefractive keratectomy
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 200 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Jan 2001to 1 Sep 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 2 to 17 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Children aged 2 to 17 with significant anisometropia or isoametropia and amblyopia that have failed traditional treatment for at least 6 months.
- Anisometropic group:
- The anisometropia must be at least 3.00 diopters.
- The amblyopic eye best corrected visual acuity must be at least 2 lines worse than the fellow eye in verbal children
- Isoametropic group
- Myopia must be at least -4.00 diopters in both eyes
- Hyperopia must be at least +4.00 diopters in both eyes
- Astigmatism must be at least +2.50 diopters in both eyes.
Who cannot join
- History of significant corneal abnormality that, in the investigator's opinion, may limit visual rehabilitation.
- History of known collagen disorder
- History of known corneal ectasia
- History of previous herpes simplex keratitis
- Corneal thickness of less than 450u
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Photorefractive Keratectomy for Anisometropic and Isoametropic Amblyopia in Children Refractory to Conventional Treatment
Photorefractive keratectomy (PRK) with excimer laser has been used successfully to treat myopia, hyperopia, and astigmatism in adults for over 35 years. Children with high refractive errors that go untreated will develop severe amblyopia. PRK can normalize high refractive errors and potentially improve the visual acuity in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity.
Read the detailed description
Anisometropia is a condition in which one eye has a significantly different refractive error from the other and commonly leads to the development of refractive amblyopia in the affected eye. High isoametropia is the condition in which both eyes have high refractive error and commonly leads to bilateral refractive amblyopia if untreated. Amblyopia is the condition in which vision does not develop fully in the brain due to disuse or misuse of one or both eyes. Typically, in high anisometropia, a contact lens in the eye with the stronger refractive error and/or glasses must be used to correct the refractive error. Commonly, infants and children with this condition refuse to wear the contact lens or glasses because the other eye sees normally. There are other problems in treating high anisometropia with glasses. One is aniseikonia, the condition of image size disparity between the two eyes. This causes difficulty for the brain of the affected person to fuse the images from the two eyes because the image from one eye is much larger than that from the other eye. This results in asthenopia (eye fatigue) and sometimes even diplopia. If the anisometropia is severe, significant amblyopia will result in the eye with the stronger refractive error and, if not treated at an early age, permanent and potentially severe vision loss will result.
In high isoametropia, contact lenses or glasses must likewise be used in order for normal vision to develop. Most children with isoametropia will wear glasses well because they cannot see well without them. By contrast, children with developmental delays, chromosomal abnormalities, autism, or attention deficit hyperactivity disorder and high isoametropia very commonly will not wear the needed refractive correction due to strong tactile aversion to anything touching their face or head. If the refractive error is high, significant bilateral (isoametropic) amblyopia will result and, if not treated at an early age, permanent and potentially severe vision loss will result.
PRK can normalize high refractive errors and potentially reduce or eliminate the amblyopia in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity. Secondary outcomes are stability of refractive correction, and corneal health.
- Conditions
- Anisometropia, Hyperopia, High Myopia, Amblyopia Isometropic, Amblyopia Bilateral, High Astigmatism
- Being tested
- Photorefractive keratectomy
- Medical subject headings
- Anisometropia, Hyperopia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Photorefractive keratectomyProcedure or surgery
| Study group | Role | What they receive |
|---|---|---|
| Photorefractive keratectomy | Other | The children will undergo PRK in the affected eye(s) using previously derived formulas for PRK. Receives: Procedure: Photorefractive keratectomy |
What is being measured
The primary outcome is the main question the study is designed to answer.
Visual acuity
Snellen equivalent
Measured: 10 years
Secondary outcomes (2)
Refractive error
cycloplegic refraction
Measured: 10 years
Corneal clarity
slit lamp exam
Measured: 10 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Aug 2018
- Study start1 Jan 2001
- Primary completion1 Sep 2024
- Study completion1 Sep 2024
Why it stopped: Participants no longer receiving intervention
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AnisometropiaStudies of the same condition, open and under way.
- More trials run by Baylor College of MedicineThe sponsor's other registered studies.
- 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 N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Photorefractive Keratectomy
- Masking
- None (open label)
- Enrolment
- 200 participants (actual)
Sponsor and investigators
- Lead sponsor
- Baylor College of Medicine
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Evelyn Paysse, Baylor College of Medicine
- Investigators
- Evelyn Paysse, MD, Principal investigator, Baylor College of Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03610997
- Sponsor's protocol ID
- H-6604
- Status last verified
- Dec 2025
- First submitted
- 19 Jul 2018
- Last updated
- 8 Dec 2025
- Results posted
- No
- Data monitoring committee
- Yes
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 8 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Photorefractive Keratectomy for Anisometropic and Isoametropic Amblyopia in Children Refractory to Conventional Treatment
- ClinicalTrials.gov ID
- NCT03610997
- Acronym / sponsor ID
- H-6604
- Conditions
- Anisometropia, Hyperopia, High Myopia, Amblyopia Isometropic, Amblyopia Bilateral, High Astigmatism
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Participants no longer receiving intervention
- Enrolment
- 200 participants (actual)
- Lead sponsor
- Baylor College of MedicineUniversity, hospital or other
- Study start
- 1 Jan 2001 (actual)
- Primary completion
- 1 Sep 2024 (actual)
- Study completion
- 1 Sep 2024 (actual)
- First posted
- 2 Aug 2018 (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.
Photorefractive keratectomy (PRK) with excimer laser has been used successfully to treat myopia, hyperopia, and astigmatism in adults for over 35 years. Children with high refractive errors that go untreated will develop severe amblyopia. PRK can normalize high refractive errors and potentially improve the visual acuity in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity.
Detailed description
Anisometropia is a condition in which one eye has a significantly different refractive error from the other and commonly leads to the development of refractive amblyopia in the affected eye. High isoametropia is the condition in which both eyes have high refractive error and commonly leads to bilateral refractive amblyopia if untreated. Amblyopia is the condition in which vision does not develop fully in the brain due to disuse or misuse of one or both eyes. Typically, in high anisometropia, a contact lens in the eye with the stronger refractive error and/or glasses must be used to correct the refractive error. Commonly, infants and children with this condition refuse to wear the contact lens or glasses because the other eye sees normally. There are other problems in treating high anisometropia with glasses. One is aniseikonia, the condition of image size disparity between the two eyes. This causes difficulty for the brain of the affected person to fuse the images from the two eyes because the image from one eye is much larger than that from the other eye. This results in asthenopia (eye fatigue) and sometimes even diplopia. If the anisometropia is severe, significant amblyopia will result in the eye with the stronger refractive error and, if not treated at an early age, permanent and potentially severe vision loss will result.
In high isoametropia, contact lenses or glasses must likewise be used in order for normal vision to develop. Most children with isoametropia will wear glasses well because they cannot see well without them. By contrast, children with developmental delays, chromosomal abnormalities, autism, or attention deficit hyperactivity disorder and high isoametropia very commonly will not wear the needed refractive correction due to strong tactile aversion to anything touching their face or head. If the refractive error is high, significant bilateral (isoametropic) amblyopia will result and, if not treated at an early age, permanent and potentially severe vision loss will result.
PRK can normalize high refractive errors and potentially reduce or eliminate the amblyopia in affected children. The purpose of this study is to investigate whether children with high anisometropia or isoametropia with amblyopia that are nonresponsive to standard therapy and receive PRK develop better longterm visual acuity. Secondary outcomes are stability of refractive correction, and corneal health.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Photorefractive Keratectomy
| Arm | Type | Receives |
|---|---|---|
| Photorefractive keratectomy | Other | Procedure: Photorefractive keratectomyThe children will undergo PRK in the affected eye(s) using previously derived formulas for PRK. |
Who may qualify
- Ages
- 2 to 17 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
Key inclusion criteria (8 listed)
- Children aged 2 to 17 with significant anisometropia or isoametropia and amblyopia that have failed traditional treatment for at least 6 months.
- Anisometropic group:
- The anisometropia must be at least 3.00 diopters.
- The amblyopic eye best corrected visual acuity must be at least 2 lines worse than the fellow eye in verbal children
- Isoametropic group
Key exclusion criteria (5 listed)
- History of significant corneal abnormality that, in the investigator's opinion, may limit visual rehabilitation.
- History of known collagen disorder
- History of known corneal ectasia
- History of previous herpes simplex keratitis
- Corneal thickness of less than 450u
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 |
|---|---|---|
| Photorefractive keratectomy | Procedure or surgery | Photorefractive keratectomy |
Primary outcome
Visual acuity
Time frame: 10 years
Snellen equivalent
2 secondary outcomes
Refractive error
Time frame: 10 years
Corneal clarity
Time frame: 10 years
Results and safety
The study was stopped early (reason given: Participants no longer receiving intervention). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Dec 2025.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Evelyn Paysse, MD principal investigator
Baylor College of Medicine
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Photorefractive keratectomy in people with Anisometropia and Hyperopia, run by Baylor College of Medicine at 1 site in United States.
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 8 inclusion and 5 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: stopped early, as of the sponsor's last update on 8 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. 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. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was stopped early (reason given: Participants no longer receiving intervention). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Visual acuity (time frame: 10 years). 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 8 Dec 2025.