The main objective of this randomized trial comparing vision therapy to observation is to determine the short-term effectiveness of vision therapy on distance intermittent exotropia control. The results will help determine whether to proceed to a full-scale, long-term randomized trial.
Age 8 - 16 years
Distance exodeviation of 15∆ to 35∆ by prism alternating cover test (PACT)
IXT, exophoria, or orthophoria at near
Near exodeviation that does not exceed the distance exodeviation by more than 10∆
Treatment for IXT or amblyopia (other than refractive correction) within 3 months prior to enrollment
Office-based vision therapy for IXT within 6 months prior to enrollment
Prior office-based vision therapy for IXT of ≥10 sessions
Prior strabismus, intraocular, or refractive surgery (including BOTOX injection)
Parallel
Vision Therapy
Other intervention20 consecutive weeks of office-based vision therapy with home therapy that aim to improve the participant's vergence skills, accommodative skills, and sensory fusion.
Mean Distance Control Score
The primary analysis will be an intent-to-treat comparison of mean distance control score, determine by the intermittent exotropia office control scale, at outcome using an analysis of covariance model, which will adjust for baseline distance control. The intermittent exotropia office control scale grades the control on a scale of 0 (best control; phoria) to 5 (worst control; constant exotropia).
No Spontaneous Tropia
The proportion of participants with no spontaneous tropia at outcome will be compared between treatment groups.No spontaneous tropia is defined as control score of 2 or less on all three assessments of control at distance and near and no exotropia lasting more than 5 seconds throughout the examination.
Change in Distance Control
The proportion of participants with \>= 1 point change in control and \>= 2 points change in control will be compared between treatment groups.
Change in Vergence and Accommodative Measures
The near point of convergence, positive and negative fusional vergence ranges at distance and near, vergence facility, accommodative amplitude, and accommodative facility at outcome will be compared between treatment groups adjusting for the corresponding baseline value. The analysis will be completed separately for each vergence and accommodative measures.
Suppression Status
Suppression status will be compared at outcome between treatment groups, adjusting for baseline suppression status. Suppression status when the participant's eyes are in tropic position will be assessed using the suppression scale ranging from 0 (negligible suppression) to 4 (dense suppression).
Objective Eye Movement Recordings
Frequency of intermittent exotropia by objective eye movement recordings will be compared between treatment groups.
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Southern California College of Optometry at Marshall B. Ketchum University
Lead sponsor
Stanford University
Collaborator
Ohio State University
Collaborator
Salus University
Collaborator
University of Alabama at Birmingham
Collaborator
Southern College of Optometry
Collaborator
Case Western Reserve University
Collaborator
American Academy of Optometry
Collaborator
