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Optimizing home-based vision training for convergence insufficiency in young adults using automatic dual rotational
Ya-Yu Chen1, Po-Hao Ternence Chen, Shuan-Yu Huang
1Department of Optometry, Mackay Medical College, New Taipei, Taiwan College of Optometry, Pacific University, Forest Grove, Oregon Department of Optometry, Central Taiwan University of Science and Technology, Taichung, Taiwan Department of Ophthalmology, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
Significance:
Automatic dual rotational Risley prisms are a novel, mobile phone-operated device providing variable prism power for home-based visual therapy. Patients with symptomatic convergence insufficiency may experience improvements in visual symptoms, near exodeviation, near point of convergence, and positive fusional vergence after this therapy.
Purpose:
To investigate the effects of automatic dual rotational Risley prisms training on symptoms and visual function in individuals with convergence insufficiency.
Methods:
Prospective, interventional pilot study enrolling patients aged 19-30 years with convergence insufficiency. Eligibility criteria included a Convergence Insufficiency Symptom Survey (CISS) score ≥21, near point of convergence ≥6 cm, near exodeviation at least 4[INCREMENT] greater than distance, and positive fusional vergence ≤15[INCREMENT]. Participants (n = 14) were divided into visual training (n = 10) and control (n = 4) groups. The training group underwent visual training for 15 minutes/day, 3 times/week, for 12 weeks. Visual function and symptoms were assessed at baseline and during follow-up visits at weeks 4, 6, and 12.
Results:
Fourteen participants (mean age: 22.9 ± 3.8 years; 64% female) completed the study. After 12 weeks, the training group showed significant improvements in CISS scores (32.9 ± 10.1 to 14.9 ± 12.5, p=0.005), near positive fusional vergence (14.0 ± 7.7[INCREMENT] to 39.0 ± 22.6[INCREMENT], p=0.005), near exodeviation (10.9 ± 4.0[INCREMENT] to 6.4 ± 5.3[INCREMENT], p=0.01), and accommodative convergence/accommodation ratio (3.1 ± 1.6 to 4.7 ± 1.7, p=0.007). Statistically significant improvements were also observed in accommodative facility (right eye: p=0.02; left eye: p=0.008) and vergence facility (p=0.007), while near point of convergence showed a nonsignificant trend (p=0.06). No significant changes were found in the control group. Between-group comparisons from baseline to 12 weeks showed greater improvements in the training group for CISS scores (p=0.02), positive fusional vergence (p=0.004), near exodeviation (p=0.04), and accommodative convergence/accommodation ratio (p=0.02).
Conclusions:
Preliminary results suggest that home-based automatic dual rotational Risley prisms training may improve visual symptoms, near exodeviation, near point of convergence, and positive fusional vergence in individuals with convergence insufficiency over 12 weeks. Further studies are needed to assess its long-term effects.
