Effectiveness of Office-Based Vergence and Anti-Suppression Therapy for the Treatment of Small-to-Moderate Angle Intermittent Exotropia
abstract
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Access this abstract nowPURPOSE
To evaluate the short-term (1 week after completion of treatment) effect of office-based vergence and anti-suppression therapy (OBVAT) on the Office Control Score when compared to observation alone in children with small-to-moderate angle intermittent exotropia (IXT).
METHODS
In this single-masked (examiner masked), two-arm, single-centre randomised clinical trial, 40 participants, 6 to <18 years of age with untreated IXT, were randomly assigned to OBVAT or observation alone. Participants assigned to therapy received 60 min of OBVAT with home reinforcement once per week for 16 weeks. Therapy included vergence, accommodation and anti-suppression techniques. The primary outcome measure was the comparison of the distance Office Control Score between the two groups at the primary outcome visit (i.e., 17-week follow-up visit).
RESULTS
At the primary outcome visit, the OBVAT group (n = 20) had a significantly better distance Office Control Score (adjusted mean difference: -0.9; 95% CI: -0.2 to -1.5; p = 0.008; partial eta squared: 0.19) than the observation group (n = 16). Participants from the OBVAT group were more likely than those from the observation group to have ≥1 point of improvement at the 17-week visit (OBVAT group: 75%; Observation group: 25%; p = 0.006).
CONCLUSIONS
In this randomised clinical trial of participants aged 6 to <18 years with IXT, we found that the OBVAT group had a significantly better distance Office Control Score than the observation group at the 17-week visit. This study provides the first data from a randomised clinical trial demonstrating the effectiveness of OBVAT for improving the control of IXT. Eye care practitioners should consider OBVAT as a viable, non-surgical treatment option for IXT. A full-scale randomised clinical trial investigating the long-term effectiveness of OBVAT in treating IXT is warranted.
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Additional Info
Office-based vergence and anti-suppression therapy for the treatment of small-to-moderate angle intermittent exotropia: A randomised clinical trial
Ophthalmic Physiol Opt 2023 Dec 26;[EPub Ahead of Print], MM Ma, Y Kang, M Scheiman, Q Chen, X Ye, L Pan, J Deng, G Su, G Zhang, X ChenFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Ma et al conducted a short-term randomized clinical trial (RCT) to compare the effect of office-based vergence and anti-suppression therapy (OBVAT) with that of observation alone in children aged 6 to <18 years who had a small-to-moderate angle intermittent exotropia (IXT). The OBVAT group received 60 minutes of in-office vision therapy in combination with supplemental home therapy once per week for 16 weeks. The therapy included vergence, accommodation, and anti-suppression techniques. The primary outcome was a comparison of the distance Office Control Score (OCS), which is designed to measure the outcomes of IXT treatment, between the two groups. The OBVAT group demonstrated a significantly better distance OCS than the observation group.
This is the first RCT to demonstrate that nonsurgical treatment can change the OCS. To date, other nonsurgical treatment methods, such as prism, occlusion, and minus lens therapies, have resulted in minimal or no improvement in the OCS over time.1–3
This article provides the first data from an RCT that demonstrated the effectiveness of OBVAT in improving the control of IXT. The authors concluded that "eye care practitioners should consider OBVAT as a viable, nonsurgical treatment option for IXT."
That being said, I believe that the treatment paradigm can be improved by initiating treatment with the development of diplopia awareness during deviation (pathological diplopia) and beginning divergence therapy.4 This might sound counterintuitive; however, one must remember that patients with IXT usually exhibit a distance deviation greater than the distance divergence fusional amplitudes, suppression upon deviation, and covariation of the angle of anomaly, resulting in harmonious anomalous retinal correspondence. Developing fusional amplitudes past the angle of deviation will result in normal retinal correspondence and elimination of suppression. Pathological diplopia is essential to achieve a cure, not just an improvement.
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