Outcome of Strabismus Surgery and Vision Therapy in a Case of Intermittent Exotropia

Background: Horizontal ocular deviations in which the visual axis deviates outward are called exodeviations. Children with exodeviations typically present during the first decade. The prevalence is approximately 1 percent in children younger than 11 years [1]. Intermittent exotropia is a common form of strabismus occurring in about 25% of all strabismic cases and in 1% of the general population. Its age of onset varies but is often between 6 months and 4 years [2,3] it is an ocular deviation that at times is completely controlled by positive fusional vergence and presents as an exophoria and at other times is not controlled by positive fusional vergence and presents as an exotropia [2]. In view of the intermittent nature of the problem and unclear course of the disease, very often the patients are reluctant to accept as first choice the surgical form of treatment which therefore is avoided or delayed. Intermittent exotropia is the most common exodeviation of childhood, affecting almost 1 percent of the general population. The usual onset occurs when the child is two to three years of age [4]. Strabismus surgery is performed for functional reasons, to create comfortable single binocular vision or, if this cannot be accomplished, to re-establish a normal facial configuration by aligning the eyes. As an alternative, various non-surgical approaches to the problem have been tried with varied results [5]. Regarding orthoptic management, a lot of controversy still exist [6]. Some authors deny the role of orthoptic treatment [7], while others found it to be effective in certain types of intermittent exotropia [8], while still others considered that combined therapy (surgery with orthoptic treatments) is a better approach to attain long term stability of results [9]. Case: Bilateral lateral rectus recession was done along with passive vision therapy by spectacles and active vision therapy by brock string exercise was given to a 19 years old male from Thankot, Kathmandu who presented to the OPD of B.P. Koirala Lions Center for Ophthalmic Studies having intermittent exotropia for both near and distance. He presented to the OPD for plan of strabismus management. He had been wearing his current prescription of glasses since one year and had deviation of eyes on and off since 2 years. His presenting visual acuity was 6/6-3 in right eye and 6/9+2 in left eye with prescription of -1.75 DS and -4.00DS in right and left eye respectively. Cover test revealed intermittent exotropia of 45∆ intermittent exotropia with 6∆ L/R for both near and distance. The full cycloplegic refraction was performed with best corrected visual acuity of 6/6 with -1.50 DS in OD and 6/6 with -4.00/-0.50 X 090 in OS. Bilateral 8.5mm Lateral rectus recession was performed and vision therapy was given. After one year of vision therapy and surgical correction he had only 4∆ esophoria for both near and distance. He had no symptom of aesthenopia and vision related complain at the completion of the therapy. Conclusion: Active and passive vision therapy along with strabismus surgery helps in the management of intermittent exotropia and helps in the restoration of binocular single vision with clear and comfortable vision and good cosmesis of the eyes.