Office-based Vergence and Accommodative Therapy for the Treatment of Intermittent Exotropia: A Pilot Study

Abstract

SIGNIFICANCE This study will help to demonstrate the potential value of office-based vergence/accommodative therapy for the treatment of intermittent exotropia and provide data that can be used for planning future clinical trials. PURPOSE This study was designed to evaluate changes in the office control score after office-based vergence/accommodative therapy for intermittent exotropia. METHODS This was a prospective, unmasked pilot study. Fourteen Chinese participants aged 6 to 18 years with intermittent exotropia (excluding the convergence insufficiency type) were enrolled. All participants received 60 minutes of office-based vergence/accommodative therapy with home reinforcement once per week for 12 weeks. Therapy included vergence, accommodation, saccades and pursuits, antisuppression, and monocular fixation in binocular field techniques. The primary outcome measure was the change in the office control score from the baseline visit to the 13-week outcome visit. RESULTS All participants completed the study. The office control score at distance changed by −1.0 (95% confidence interval [CI] = −1.6 to −0.4; P = .005; Cohen's d effect size, 0.93). The distant Look And Cover, then Ten seconds Observation Scale for Exotropia score and distant Newcastle control score total score changed by −0.7 (95% CI, −1.2 to −0.2; P = .02; Cohen's d effect size, 0.55) and −1.9 (95% CI, −2.8 to −1.0; P < .001; Cohen's d effect size, 1.37), respectively. Although there was no significant change in the angle of distance exodeviation (−1.8 prism diopter [Δ] less exodeviation; 95% CI, −3.74 to 0.14Δ; P = .11), a significant change was observed in the near angle (−4.4Δ less exodeviation; 95% CI, −7.3 to −1.5Δ; P = .01; Cohen's d effect size, 0.79). There was no significant change in stereopsis or the Chinese Intermittent Exotropia Questionnaire score. CONCLUSIONS In this select group of children with intermittent exotropia, 12 weeks of office-based vergence/accommodative therapy with home reinforcement resulted in a statistically and clinically significant improvement in the distance control of exodeviation and the near exodeviation magnitude. These results suggest that there is a need for a randomized clinical trial designed to determine the effectiveness of vision therapy as a treatment modality for intermittent exotropia.

Study on Binocular Accommodative Function in Children With Different Types of Intermittent Exotropia

“…Therefore, the influence of refractive factors can be excluded. Accommodative problems increase the risk of myopia in young children with IXT ( 19 ), and myopia and IXT are considered important co-existing diseases ( 20 ). This is reflected in the overlapping and mutual promotion of the pathogenesis and progression of the two diseases.…”

Reliability of step vergence method for assessing fusional vergence in intermittent exotropia

“…7 Other parameters have also been proposed, and these include, but are not limited to the fusion maintenance score, 8 distance stereopsis, 9,10 vergence, [9][10][11][12][13][14][15] near point of convergence, 10,11 accommodative function 9,[12][13][14] and suppression. 10,11 Treatment of intermittent exotropia includes surgical and nonsurgical options (watchful observation, 16 patching, 16 prisms, 17 overminus lenses 18 and vision therapy/orthoptics 19,20 ).…”

“…Thus, fusional vergence appears to be an important outcome measure in studies investigating vision therapy, and this is supported by multiple previous studies of vision therapy as a treatment for intermittent exotropia. [9][10][11][12]20,25 Fusional vergence can be measured clinically by synoptophore or rotary prisms (smooth vergence method), but is most commonly assessed using a prism bar (step vergence method). 22,23,[26][27][28] The repeatability of the fusional vergence assessment has been reported in individals with normal binocular vision 29 and convergence insufficiency, 30 but not in those with intermittent exotropia.…”

A survey of clinical opinions and preferences on the non-surgical management of intermittent exotropia in China

“…In light of these concerns, non-surgical management, due to its noninvasive nature, has been recommended to defer or even avoid surgery 13, 14 . Current non-surgical options include observation 15 , part-time patching 16 , overminus lenses 17 , prisms 18 , and orthoptic exercises 19 . However, to date, there is not a clear understanding of which option benefits patients most.…”