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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
Results First Posted : October 17, 2022
Last Update Posted : October 17, 2022
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 : 61 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Masking Description: At the 8-week outcome visit, a Masked Examiner, who is a pediatric ophthalmologist, pediatric optometrist, or certified orthoptist, will assess the control of the exodeviation and perform PACT testing. The Masked Examiner must be someone other than the investigator.
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 1, 2019
Actual Primary Completion Date : July 30, 2020
Actual Study Completion Date : July 30, 2020

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. Exotropia Control Score at Distance, Continuous 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. Distance control scores range from 0 to 5 with higher scores indicating a worse outcome.


Secondary Outcome Measures :
  1. Exotropia Control Score at Distance, % With Treatment Response [ Time Frame: 8 weeks ]
    The secondary analysis will calculate the percentage 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. Exotropia Control Score at Distance and Near, % With 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. Exotropia Control Score at Distance, Continuous Change Between Baseline and 8 Weeks [ Time Frame: 8 Weeks ]
    Control of the exodeviation was measured at distance using the IXT Office Control Score, (Mohney, 2006) which ranges from 0 (phoria) to 5 (constant exotropia). Control levels 3-5 were assigned based on the duration of manifest exotropia during a 30-second period before any dissociation. If no exotropia was observed, control levels 0-2 were assigned based on the longest time to reestablishing fusion after 3 consecutive 10-second periods of dissociation. Control was measured at the beginning, middle, and end (3 tests) of a 20- to 40-minute office examination, and the mean was used. The change in distance control from baseline to 8 weeks will be calculated. A negative value indicates improvement.

  4. Exotropia Control Score at Near, Continuous Score [ Time Frame: 8 Weeks ]
    Near control will be evaluated similarly to the primary outcome and outcome measures 2-4. Near control scores range from 0 to 5 with higher scores indicating a worse outcome.

  5. Exodeviation by PACT at Distance, Continuous [ Time Frame: 8 Weeks ]
    The measure of ocular alignment at distance by PACT will be summarized at 8 weeks for each treatment group. A higher deviation is worse.

  6. Exodeviation by PACT at Near, Continuous [ Time Frame: 8 Weeks ]
    The measure of ocular alignment at near by PACT will be summarized at 8 weeks for each treatment group. A higher deviation is worse.

  7. Randot Preschool Stereoacuity at Near, Continuous [ Time Frame: 8 Weeks ]
    Randot® Preschool Stereoacuity test (Stereo Optical Co., Inc., Chicago, IL). For analysis, stereoacuity was converted from seconds of arc scores to log arcsec values (in parentheses) as follows: 40 (1.60), 60 (1.78), 100 (2.00), 200 (2.30), 400 (2.60), 800 (2.90); participants with no detectable (nil) stereoacuity were assigned the value of 1600 (3.20). The measure of Randot Preschool Stereoacuity at near will be summarized at 8 weeks for each treatment group. A lower score is better.

  8. 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.


  9. Child Assessment of Symptoms - Do Your Eyes Hurt? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  10. Child Assessment of Symptoms - Do Your Eyes Feel Funny? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  11. Child Assessment of Symptoms - Do You Have Double Vision? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  12. Child Assessment of Symptoms - Is it Hard for You to Stare at Things? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  13. Child Assessment of Symptoms - Do You Have Problems With Your Eyes in the Sun? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  14. Child Assessment of Symptoms - Do Your Eyes go in and Out? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  15. Child Assessment of Symptoms - Is it Hard to Focus Your Eyes? [ Time Frame: 8 Weeks ]
    Adverse symptoms of intermittent exotropia will be summarized 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. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.

  16. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Had Headaches? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  17. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Had Eyestrain? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  18. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Avoided Reading or Doing Things up Close? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  19. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Reported Blurry Vision? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  20. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Looked Over His or Her Spectacles? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  21. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Taken His/Her Spectacles Off When he/She Should be Wearing Them? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.


  22. Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Complained That the Spectacles Hurt His/Her Ears and/or Nose? [ Time Frame: 8 Weeks ]

    Adverse symptoms of intermittent exotropia and spectacle wear will be summarized at the 8-week outcome exam using a symptom survey that is administered to the parent.

    Response options are based on frequency of observations: never, almost never, sometimes, often, and almost always. The distribution of scores on each survey item will be tabulated by treatment group after 8-weeks.



Other Outcome Measures:
  1. Distance Visual Acuity (Snellen Equivalent) [ Time Frame: 8 Weeks ]
    Distance visual acuity will be assessed at the 8-week outcome exam. Any optotype method can be used for testing. The distribution of distance visual acuity Snellen Equivalents will be tabulated for each treatment group. A lower Snellen Equivalent is best.

  2. Fusional Convergence - Continuous Break Point [ Time Frame: 8 Weeks ]
    As an exploratory analysis, the distribution of fusional convergence amplitude (break point, blur point, and recovery) at 8 weeks will be summarized for each treatment group. Fusional amplitudes are a measure of how well a participant can converge their eyes using fusional vergence. It is measured by increasing base-out prism to the point that the participant is no longer able to control the deviation. The total amount of fusion is the magnitude of the base-out prism the participant was able to overcome plus the magnitude of the deviation. A higher number of prism diopters for break point is better than a lower number. A lower number for recovery point is better than a higher number.

  3. Suppression [ Time Frame: 8 Weeks ]
    The suppression assessment is a standardized method of assessing the depth of suppression experienced while the participant is tropic (NOT aligned). Scoring is reported on an ordinal scale from 0 (no suppression) to 3 (dense suppression). "Missing" refers to cases in which participants were unable to understand the test and/or gave unreliable responses. As an exploratory analysis, the distribution of suppression level (none, mild, moderate, severe, missing) will be tabulated after 8 weeks by treatment group.

  4. Fusional Convergence - Continuous Recovery Point [ Time Frame: 8 Weeks ]
    As an exploratory analysis, the distribution of fusional convergence amplitude (break point, blur point, and recovery) at 8 weeks will be summarized for each treatment group. Fusional amplitudes are a measure of how well a participant can converge their eyes using fusional vergence. It is measured by increasing base-out prism to the point that the participant is no longer able to control the deviation. The total amount of fusion is the magnitude of the base-out prism the participant was able to overcome plus the magnitude of the deviation. A higher number of prism diopters for break point is better than a lower number. A lower number for recovery is better than a higher number.



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:
Study Protocol  [PDF] May 29, 2019
Statistical Analysis Plan  [PDF] April 15, 2020
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
Results First Posted: October 17, 2022
Last Update Posted: October 17, 2022
Last Verified: October 2022
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