Base-in Prism Spectacles for Intermittent Exotropia

Study Overview
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Brief Summary
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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

Official Title
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Intermittent Exotropia Study 6: A Pilot Randomized Clinical Trial of Base-in Prism Spectacles for Intermittent Exotropia

Conditions
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Exotropia Intermittent

Intervention / Treatment
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* Device: Prism Glasses
* Device: Non-Prism Glasses


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 3 Years
Maximum Age: 13 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Prism Group<br>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<br>* 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<br>|
| Placebo Comparator: Non-Prism Group<br>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<br>* Spectacles with refractive correction (or plano spectacles if no significant refractive error) and no prism<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Exotropia Control Score at Distance, Continuous Score | 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. | 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Exotropia Control Score at Distance, % With Treatment Response | 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. | 8 weeks | 
| Exotropia Control Score at Distance and Near, % With No Spontaneous Tropia | 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. | 8 Weeks | 
| Exotropia Control Score at Distance, Continuous Change Between Baseline and 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. | 8 Weeks | 
| Exotropia Control Score at Near, Continuous Score | 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. | 8 Weeks | 
| Exodeviation by PACT at Distance, Continuous | The measure of ocular alignment at distance by PACT will be summarized at 8 weeks for each treatment group. A higher deviation is worse. | 8 Weeks | 
| Exodeviation by PACT at Near, Continuous | The measure of ocular alignment at near by PACT will be summarized at 8 weeks for each treatment group. A higher deviation is worse. | 8 Weeks | 
| Randot Preschool Stereoacuity at Near, Continuous | 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 Weeks | 
| Compliance of Spectacle Wear | 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. | 8 weeks | 
| Child Assessment of Symptoms - Do Your Eyes Hurt? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Do Your Eyes Feel Funny? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Do You Have Double Vision? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Is it Hard for You to Stare at Things? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Do You Have Problems With Your Eyes in the Sun? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Do Your Eyes go in and Out? | 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. | 8 Weeks | 
| Child Assessment of Symptoms - Is it Hard to Focus Your Eyes? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Had Headaches? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Had Eyestrain? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Avoided Reading or Doing Things up Close? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Reported Blurry Vision? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Looked Over His or Her Spectacles? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Taken His/Her Spectacles Off When he/She Should be Wearing Them? | 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. | 8 Weeks | 
| Parent Assessment of Symptoms and Spectacle Wear - Has Your Child Complained That the Spectacles Hurt His/Her Ears and/or Nose? | 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. | 8 Weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Prism