Effect of vision therapy on fusional vergences in intermittent exotropia

Abstract

Significance: Intermittent exotropia is intermittently manifest squint at distance and latent exophoria at near. Most of the time, the eyes seems to be aligned with normal binocular single vision is maintained because its exodeviation is intermittently controlled by fusional mechanisms. Purpose: To evaluate the effect of vision therapy on fusional vergences in intermittent exotropia. Methods: This hospital-based, Quasi-Experimental study was carried out at the Orthoptics clinic of Al-Ibrahim Eye Hospital from August 2020 to July 2021. Non- probability, purposive sampling was used. This study involved the 40 subjects who were diagnosed with Intermittent Exotropia of age ranges 10 to 25 years, of both genders. A detailed history was evaluated. Orthoptics assessment included visual acuity, cover test, near the point of accommodation and convergence at a distance, and near and fusional vergences of positive and negative with prisms were measured. All subjects underwent vision therapies for 2 months. SPSS version 20.0 was used to analyze the data. Results: A total of 40 subjects with a mean age of 16.53±2.96 were included in this study. Out of 40 subjects, 22 subjects were females and 18 subjects were males. Subjects who received dot card therapy and executives bifocals therapy showed a significant change in the angle of deviation at distance and near (P=.001), followed by reduced the near point of convergence (P=.001), and increased the positive fusional vergences at distance and near (P=.001). There was no significant improvement seen in near point of accommodation (P=.16) with both therapies. Negative fusional vergences showed non-significant as (near: P=.14, distance: P=.05) with executives bifocals and (P=.26) with dot cards. Conclusions: This study showed that vision therapies with dot card and executive bifocals therapy have significantly improved the angle of deviation, positive fusional vergences, and near point of convergence in intermittent exotropia subjects.