Improving Control of Alignment in Intermittent Exotropia

Aim 1: To determine whether use of dichoptic movies for 4 weeks may be helpful in improving control of alignment in children with intermittent exotropia (IXT), thus allowing IXT to be managed non-surgically Aim 2: To determine pre-IXT surgery use of dichoptic movies for 4 weeks post-operatively may be helpful in maintaining successful control of alignment in children who have surgical correction of IXT

Study Overview

• Status: Recruiting
• Conditions: Intermittent Exotropia
• Intervention / Treatment: Other: dichoptic 3D movies

Detailed Description

The most common childhood-onset exotropia is intermittent exotropia (IXT). IXT is an exotropia that is not constant and is mainly present at distance, but may also be present at near. Binocular single vision is typically present at near but may be subnormal. There is some debate in the literature about whether or not these children should be treated surgically to correct the misalignment. It can be argued that prompt surgical correction is necessary to prevent the development of suppression of the deviating eye, progression to constant exotropia, and permanent changes in sensory function that may compromise long-term post-operative outcomes. On the other hand, statistics on the natural history of IXT suggest that progression to constant XT occurs in less than 25% and up to 15% may improve spontaneously. These findings suggest a more conservative approach, using surgery only if deterioration of the IXT occurs. A recent randomized clinical trial of the two most common surgical techniques for IXT revealed a 3-year postoperative failure rate of approximately 40% (PEDIG 2019; Ophthalmology 126: 305-17). For the vast majority of children, surgical failure was due to recurrence of the exodeviation. Only about 30% of treated children had resolution of IXT at the 3-year visit. Similarly, a literature review of 28 surgical studies that included 2530 children with IXT reported a suboptimal surgical outcome at 1-year post-op in approximately 40% of children. (Coffey et al 1992; Optom Vis Sci 69: 386-404).

Poor surgical results for IXT are thought to occur due to poor sensory status (suppression) or inadequate motor alignment. There are few data on the effects of non-surgical interventions designed to improve sensory status of children undergoing surgery for IXT. Although several retrospective case reviews found evidence supporting a benefit of pre-op sensory and motor fusion training on IXT surgical outcomes, there have been no prospective studies or randomized clinical trials. One of the largest retrospective case series (Cooper & Leyman 1977; Am Orthoptic J 27:61-7) compared 216 patients with IXT who had sensory and motor fusion training prior to surgery with 264 who had surgery alone and found a higher rate of good surgical outcomes (52% vs 42%). There are no published data on post-op interventions to improved sensory status.

In this study, engaging movies will be presented on a handheld Nintendo to decrease suppression and engage stereoacuity. In previous research, use of dichoptic games and movies by children with amblyopia has been shown to reduce suppression and encourage sensory fusion (Birch et al 2015, JAAPOS 19:6-11; Birch et al 2019, JAAPOS [Epub ahead of print]; Kelly, Jost, et al 2016; JAMA Ophthalmol 134:1402-8.; Kelly et al Invest 2018 Ophthalmol Vis Sci 59:1221-8; Li et al 2014; Eye 28: 1246-53). This approach will be adapted by using dichoptic movies presented on a Nintendo for children with IXT to improve their stereoacuity and reduce their suppression in an effort improve control of alignment sufficiently without surgery (Aim 1) or to improve stability of post-operative alignment (Aim 2).

• Study Type: Interventional
• Enrollment (Estimated): 84
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Eileen E Birch, PhD; Phone Number: 2143633911; Email: ebirch@retinafoundation.org
• Study Contact Backup: Name: Reed M Jost, MS; Phone Number: 2143633911; Email: reedjost@retinafoundation.org

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75231
      • Recruiting
      • Eileen E Birch
      • Contact: Reed M Jost, MS; Phone Number: 2143633911; Email: reedjost@retinafoundation.org
      • Contact: Eileen E Birch, PhD; Phone Number: 113 214-363-3911; Email: ebirch@retinafoundation.org
      • Principal Investigator: Eileen E Birch, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 3 years to 12 years (Child)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• diagnosis of IXT
• IXT control assessment score at distance of 3 or 4 at baseline
• Ocular misalignment by PACT >10 pd at distance and near or PACT >15 at distance or near

Exclusion Criteria:

• Amblyopia
• Prior surgery
• Prior binocular treatment
• Coexisting ocular or systemic condition
• Developmental delay

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Group1; dichoptic 3D movies	Other: dichoptic 3D movies; dichoptic movies presented on a Nintendo 3DS; Other Names: dichoptic standard movies
Sham Comparator: Group 2; dichoptic standard movies	Other: dichoptic 3D movies; dichoptic movies presented on a Nintendo 3DS; Other Names: dichoptic standard movies

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Alignment Control Score	Classification system developed by PEDIG to quantify the degree of control of ocular alignment on a 0-5 scale at distance and near; 0 is best control [no exotropia unless dissociated, recovers in <1 second (phoria)] and 5 is worst control (constant exotropia)	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stereoacuity at distance	Randot Distance Stereoacuity Test	3 months
Binocular fixation stability	Stability of the vergence angle assessed by recording eye movements during 20 sec fixation	3 months
Stereoacuity at near	Randot Preschool Stereoacuity Test	3 months

Collaborators and Investigators

• Sponsor: Retina Foundation of the Southwest
• Investigators: Principal Investigator: Eileen E Birch, PhD, Retina Foundation of the Southwest

Study record dates

Study Major Dates

• Study Start (Actual): March 25, 2021
• Primary Completion (Estimated): December 1, 2024
• Study Completion (Estimated): December 1, 2024

Study Registration Dates

• First Submitted: December 11, 2019
• First Submitted That Met QC Criteria: December 13, 2019
• First Posted (Actual): December 16, 2019

Study Record Updates

• Last Update Posted (Actual): October 19, 2023
• Last Update Submitted That Met QC Criteria: October 18, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Eye Diseases; Cranial Nerve Diseases; Ocular Motility Disorders; Strabismus; Exotropia
• Other Study ID Numbers: STU-2019-1430

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No