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Base-in Prism Spectacles for Intermittent Exotropia (IXT6)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT03998670
Recruitment Status : Completed
First Posted : June 26, 2019
Last Update Posted : November 3, 2020
Sponsor:
Collaborators:
Pediatric Eye Disease Investigator Group
National Eye Institute (NEI)
Information provided by (Responsible Party):
Jaeb Center for Health Research

Brief Summary:

The objective of this short-term, pilot randomized trial comparing spectacles with relieving prism to spectacles without prism is to determine whether to proceed to a full-scale, longer-term randomized trial. This decision will be based primarily on assessing the initial (8-week) response to prism by comparing treatment groups on the following outcomes:

  • Mean distance intermittent exotropia (IXT) control score (the mean of 3 control scores) (primary outcome)
  • The proportion of participants demonstrating a "treatment response," defined as ≥1 point improvement in the mean distance IXT control score without spontaneous exotropia during control testing (secondary outcome)
  • The proportion of participants reporting adverse effects and good/excellent spectacle wear compliance

Condition or disease Intervention/treatment Phase
Exotropia Intermittent Device: Prism Glasses Device: Non-Prism Glasses Not Applicable

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 57 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Intermittent Exotropia Study 6: A Pilot Randomized Clinical Trial of Base-in Prism Spectacles for Intermittent Exotropia
Actual Study Start Date : September 30, 2019
Actual Primary Completion Date : July 30, 2020
Actual Study Completion Date : July 30, 2020

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Eye Wear

Arm Intervention/treatment
Experimental: Prism Group
Spectacles with refractive correction and base-in relieving prism (40% of the greater of the exodeviation by prism and alternate cover test (PACT) at distance or near) equally divided between the 2 lenses will be prescribed to the participant
Device: Prism Glasses
Spectacles with refractive correction and base-in relieving prism (40% of the greater of the exodeviation by PACT at distance or near) equally divided between the 2 lenses

Placebo Comparator: Non-Prism Group
Spectacles with refractive correction (or plano spectacles if no significant refractive error) and no prism will be prescribed to the participant
Device: Non-Prism Glasses
Spectacles with refractive correction (or plano spectacles if no significant refractive error) and no prism




Primary Outcome Measures :
  1. Mean Distance Control Score [ Time Frame: 8 weeks ]
    The primary analysis will be an intent-to-treat comparison of mean 8-week control of the distance exodeviation (average of 3 measurements) between treatment groups using an analysis of covariance (ANCOVA) model, which adjusts for baseline distance control.


Secondary Outcome Measures :
  1. Distance Control [ Time Frame: 8 weeks ]
    The secondary analysis will calculate the proportion (and two-sided 95% confidence interval) of participants with a "treatment response," defined as ≥1 point improvement in control of their distance exodeviation (average of 3 measurements) between baseline and the 8-week outcome exam.

  2. No Spontaneous Tropia [ Time Frame: 8 Weeks ]

    The proportion of participants with no spontaneous tropia at 8 weeks will be compared between treatment groups using a two-sided Barnard's test with alpha of 0.05, with calculation of a two-sided 95% confidence interval on the difference in proportions.

    No spontaneous tropia at the 8-week primary outcome exam is defined as a score of ≤2 (0, 1, or 2) on all three assessments of control at distance and at near.


  3. Change in Distance Control [ Time Frame: 8 Weeks ]
    The distribution of change in distance control will be compared between treatment groups using the Wilcoxon rank sum test.

  4. Near Control [ Time Frame: 8 Weeks ]
    Near control will be evaluated similarly to the primary outcome and outcome measures 2-4.

  5. Ocular Alignment [ Time Frame: 8 Weeks ]
    The distribution of measures of ocular alignment at distance and near fixation by PACT will be described for the enrollment exam and the outcome exam for each treatment group

  6. Near Stereoacuity [ Time Frame: 8 Weeks ]
    The distribution of near stereoacuity will be described for the enrollment exam and the outcome exam for each treatment group.

  7. Suppression [ Time Frame: 8 Weeks ]
    As an exploratory analysis, the distribution of suppression level (none, mild, moderate, severe) will be described for the enrollment exam and the outcome exam for each treatment group.

  8. Fusional Convergence [ Time Frame: 8 Weeks ]
    As an exploratory analysis, the distribution of fusional convergence amplitude (break point, blur point, and recovery) will be described, and compared between treatment groups for the enrollment exam and the outcome exam for each treatment group

  9. Adverse Symptoms of Intermittent Exotropia and Prism Spectacle Wear [ Time Frame: 8 Weeks ]

    Adverse symptoms of IXT will be assessed at enrollment and at the 8-week outcome exam using a symptom survey that is administered to the child. Response options are based on frequency of observations: never, sometimes, and always.

    Similarly, adverse symptoms that may be associated with prism spectacle wear will be assessed at enrollment and at the 8-week outcome exam using a spectacle survey that is administered to the parent. Response options are based on frequency of observations: never, rarely, sometimes, often, always, and not applicable.

    For each survey separately, the distribution of scores on each survey item will be described for the enrollment exam and the outcome exam for each treatment group.


  10. Distance Visual Acuity [ Time Frame: 8 Weeks ]

    Distance visual acuity will be assessed at enrollment and at the 8-week outcome exam. Any optotype method can be used for testing; however, the same method must be used at both the enrollment and 8-week outcome exam.

    The distribution of distance visual acuity measures will be described for the enrollment exam and the outcome exam for each treatment group. The distribution of change in visual acuity will also be described for each treatment group.


  11. Compliance of Spectacle Wear [ Time Frame: 8 weeks ]

    Parents will be asked to complete a compliance calendar by recording the percentage of time their child has worn the study-prescribed spectacle correction each day. Proportion of time worn each day will be described as excellent (76% to 100%), good (51% to 75%), fair (26% to 50%), poor (1 to 25%), or none (0%). Based on review of the calendars and discussion with parents at the 8-week outcome exam, the investigator will record the total proportion of time worn as excellent (76% to 100%), good (51% to 75%), fair (26% to 50%), poor (1 to 25%), or none (0%: did not fill prescription or never picked up spectacles).

    The distribution of compliance will be assessed for each treatment group at the outcome exam.




Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


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Ages Eligible for Study:   3 Years to 13 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

Intermittent Exotropia meeting all of the following criteria:

  • Age 3 to 13 years
  • Mean distance control score of ≥2.00 points with at least 1 measure of 3, 4, or 5 points (i.e, spontaneous tropia) from the 3 assessments during the exam
  • A near control score ≤4 on at least 1 of 3 assessments (cannot have score of 5, 5, 5)
  • Distance exodeviation between 16 Prism Diopters (Δ) and 35 Δ (inclusive) by PACT
  • Near exodeviation between 10 Δ and 35 Δ (inclusive) by PACT
  • Near deviation does not exceed distance deviation by more than 10 Δ by PACT (i.e., convergence insufficiency-type IXT excluded)
  • Refractive error between -6.00 Diopters (D) spherical equivalent (SE) and +2.50 D SE (inclusive) (based on a cycloplegic refraction performed within 7 months but prior to the day of enrollment)
  • Refractive correction (must be worn for at least 1 week if refractive error meets any of the following (based on a cycloplegic refraction performed within 7 months but prior to the day of enrollment):

    • SE anisometropia ≥1.00 D
    • Astigmatism ≥1.00 D in either eye
    • SE myopia ≥-0.50 D in either eye
  • If spectacles have been prescribed and are worn, they must meet the following pre- enrollment criteria:

    • SE anisometropia corrected to within 1.00 D of full SE anisometropic difference
    • Astigmatism corrected to within 1.00 D of full magnitude; axis within 10 degrees if astigmatism ≤1.00 D and axis within 5 degrees if astigmatism >1.00 D

Exclusion Criteria:

  • Dissociated vertical deviation (DVD)
  • Vertical deviation >3 Δ in primary gaze at distance or near
  • Patterns (such as an "A" or "V" pattern) with a downgaze measurement of >10 Δ difference from straight ahead by PACT, measured per investigator's routine method
  • Treatment for IXT or amblyopia (other than refractive correction) within the past 4 weeks, including vision therapy, orthoptics, patching, atropine, or other penalization
  • Substantial overminus spectacles (spectacles overminused by more than 1.00 D SE than the most recent cycloplegic refraction and also results in minus SE power in the spectacles; underplussing is allowed) within the past 4 weeks
  • Prior strabismus, intraocular, or refractive surgery (including BOTOX injection)
  • Previous use of prism spectacles

Additional Eligibility Criteria for Randomization Based on Prism Adaptation Testing

  • Exodeviation by PACT while wearing "trial" relieving prism for 30 minutes is smaller at distance or near than measured during initial testing (e.g. not fully adapting to prism at both distances)
  • No new esotropia on cover test at near while wearing "trial" relieving prism for 30 minutes, compared with enrollment measurement taken without prism
  • No esodeviation >6 Δ on PACT at near while wearing "trial" relieving prism for 30 minutes

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03998670


Locations
Show Show 28 study locations
Sponsors and Collaborators
Jaeb Center for Health Research
Pediatric Eye Disease Investigator Group
National Eye Institute (NEI)
Investigators
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Study Chair: David G Morrison, MD Vanderbilt University Medical Center
Study Chair: Allison I Summers, OD, MCR Oregon Health and Science University
  Study Documents (Full-Text)

Documents provided by Jaeb Center for Health Research:
Informed Consent Form  [PDF] June 18, 2019

Additional Information:
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Responsible Party: Jaeb Center for Health Research
ClinicalTrials.gov Identifier: NCT03998670    
Other Study ID Numbers: IXT6
2UG1EY011751 ( U.S. NIH Grant/Contract )
First Posted: June 26, 2019    Key Record Dates
Last Update Posted: November 3, 2020
Last Verified: November 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Yes
Plan Description: In accordance with the NIH data sharing policy, a de-identified database is placed in the public domain on the Pediatric Eye Disease Investigator Group (PEDIG) public website after the completion of each protocol and publication of the primary manuscript.
Supporting Materials: Study Protocol
Statistical Analysis Plan (SAP)
Informed Consent Form (ICF)
Time Frame: Data will be made available after publication.
Access Criteria: Users accessing the data must enter an email address.
URL: http://pedig.jaeb.org

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Jaeb Center for Health Research:
Prism
Additional relevant MeSH terms:
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Exotropia
Strabismus
Ocular Motility Disorders
Cranial Nerve Diseases
Nervous System Diseases
Eye Diseases
Methamphetamine
Central Nervous System Stimulants
Physiological Effects of Drugs
Sympathomimetics
Autonomic Agents
Peripheral Nervous System Agents
Dopamine Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Adrenergic Agents
Adrenergic Uptake Inhibitors
Neurotransmitter Uptake Inhibitors
Membrane Transport Modulators
Dopamine Uptake Inhibitors