An interventional study of Home-based near eye training program in Intermittent Exotropia, sponsored by The Hong Kong Polytechnic University. Recruiting at 1 site in Hong Kong. Open to participants aged 6 Years to 25 Years. Per ClinicalTrials.gov, last updated 2026-09-28.
Sponsored by The Hong Kong Polytechnic University · Not applicable, Interventional, and Treatment
Intermittent Exotropia (IXT) is a common type of eye misalignment where one eye periodically turns outward, and control is typically much worse when looking at objects far away than close up. However, most currently available training programme are focused on near-viewing tasks. The goal of this clinical trial is to investigate if a new, structured, home-based near eye training program works to improve distance eye alignment control in children and young adults with IXT.
The main questions the study aims to answer are:
This is a two- phase, single- masked (examiner masked), randomized clinical trial with crossover design. The entire study duration is about 24 weeks. A total sample size of 42 participants, aged 6 to 25 years with diagnosed Basic (distance deviation is within 10 prism diopters of the near deviation) or Divergence excess (distance deviation is at least 10 prism diopters greater than the near deviation) IXT, will be recruited.
In Phase I (Weeks 0 to 12), participants will be randomly allocated into one of three groups, with 14 individuals in each group:
In Phase II (Weeks 13 to 24), which is a crossover phase, groups 1 and 2 will stop training to see if the visual improvements last, while group 3 will be re-randomized into two subgroups (group 3A, with special plus-power reading glasses, and group 3B with regular glasses with distance correction) that will undertake daily eye training for 12 weeks to ensure ethical treatment access. All participants will have a final eye exam at 24 weeks.
During home training, participants will:
Preliminary test and binocular vision assessment with fixed and uniform sequence will be performed at baseline visit, 6th week interim visit, 12th and 24th week evaluation. All eye examinations will be carried out in The Optometry Centre (A034), the School of Optometry, The Hong Kong Polytechnic University.
The following data will be statistically analyzed. The primary outcome data is distance Office Control Score (OCS) at 12-week visit. Secondary outcomes data include change in deviation angle, near and distance stereopsis and patient- / parent- reported health-related quality-of-life questions at 12-week.
Refractive Correction Stability: Compliance with wearing a stable, appropriate spectacle correction for ≥ 4 months prior to formal baseline assessment if the participant meets any of the following refractive thresholds:
Exclusion Criteria
Receiving training in Phase I (Weeks 0 to 12), stop training in Phase II (Weeks 13 to 24) to study the effect persistence
Other: Home-based near eye training program
Receiving training in Phase I (Weeks 0 to 12), stop training in Phase II (Weeks 13 to 24) to study the effect persistence
Other: Home-based near eye training program
No training will be received in Phase I (Weeks 0 to 12); Will receive training in Phase II of the study (Weeks 13 to 24) to ensure ethical treatment access
Standardized home-based near vergence training platform with data visualization tools and communication platforms
Change of Distance Office Control Score
Objective and quantitative office control scale, based on the frequency of deviation and the recovery speed followed by occlusion. Ranged from 0 to 5, with score 0 represents the best control (phoria with excellent control), and score 5 represents the worst control (constant exotropia during the 30-second observation)
Time frame: Baseline, 6-week, 12-week and 24-week
Change of exodeviation magnitude angle
measured by Prism and Alternate Cover Test, ranged from 1 to 50 prism diopter. The higher the value, the worse is the magnitude angle of the exodeviation
Time frame: Baseline, 6-week, 12-week and 24-week
Change of Distance stereoacuity
measured by Distance Randot® stereotest, ranged from 400 seconds of arc (the worst measurable stereoacuity) to 60 seconds of arc (the best measurable stereoacuity )
Time frame: Baseline, 6-week, 12-week and 24-week
Change of Near stereoacuity
measured by Preschool Randot® stereoacuity test, ranged from 800 seconds of arc (the worst measurable stereoacuity) to 40 seconds of arc (the best measurable stereoacuity )
Time frame: Baseline, 6-week, 12-week and 24-week
Change of Quality of Life (QoL) measures - Chinese Intermittent Exotropia Questionnaire (CIXTQ) for children aged 5 to 17 and parents of children aged 2 to 17
Part a: Child CIXTQ - 12 items completed by children, simplified 3-point scale (0, 50 and 100); Part b: Proxy CIXTQ - 12 items completed by parents to evaluate their child's health-related quality-of-life (HRQoL) from a parental perspective, 5-point Likert-type (0, 25, 50, 75, and 100); Part c: Parent CIXTQ - 17 items to measure the parent's own HRQoL, 5-point Likert-type (0, 25, 50, 75 and 100). The higher the score, the better the outcome (QoL).
Time frame: Baseline, 12-week and 24-week
Change of Quality of Life (QoL) measures - The Chinese Adult Strabismus Quality of Life Questionnaire (CAS-20) for adult participants aged 18 or above
20 items to assess psychosocial impact and visual function, 5-point Likert-type (0, 25, 50, 75 and 100). Higher scores indicating better perceived QoL.
Time frame: Baseline, 12-week and 24-week
Plan to share: Undecided
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The Hong Kong Polytechnic University