Vision Therapy for Intermittent Exotropia: A Case Series

In this blog post, we summarise the intermittent exotropia vision condition: what it is, its prevalence, and its symptoms. Furthermore, we discuss the treatment options and the case study evaluating vision therapy as an under-researched treatment for intermittent exotropia.

What is Exotropia?

Exotropia is a type of strabismus and an eye condition where one or both eyes turn outward, away from the nose, when a person is looking at an object. In other words, the affected eye(s) deviate outward, while the other eye maintains its normal focus.

What is Intermittent Exotropia?

Intermittent exotropia is a type of eye misalignment, also known as a strabismus, where one eye occasionally deviates outward or away from the nose while the other eye remains aligned properly. Individuals experience outward drift occasionally, such as when they are sleepy, feeling unwell, experiencing stress, and focusing on distant objects.

Prevalence of Intermittent Exotropia

The most prevalent type of exotropia is intermittent exotropia. For example, it affects around 3% of Chinese youths. In general, it is estimated that 1% of population has this vision condition.

Symptoms of Intermittent Exotropia

This condition primarily affects binocular vision, which is the ability of both eyes to work together to create a single, merged image. In individuals with strabismus, the misalignment of the eyes disrupts binocular vision. When the eyes are misaligned, each eye sends a different image to the brain. Thus, the brain receives conflicting information from the two eyes, which can lead to visual confusion and difficulties in perceiving depth and spatial relationships.

Treatment of Intermittent Exotropia

Intermittent exotropia is treated with a combination of approaches, depending on the severity and other factors. It’s important to consult with an optometrist/vision therapist/ophthalmologist or an eye care specialist who can assess the specific needs of an individual with intermittent exotropia and recommend the most appropriate treatment approach.

Patching

In some cases, covering the vision in the dominant eye with an eye patch can encourage the weaker eye to align properly.

Prism glasses

Prisms are optical devices that can bend or redirect light, and they are used in prism glasses to alter the path of light entering the eyes. The purpose of prism correction is to help align the eyes and allow for proper binocular vision.

Overminus lens

These are a type of eyeglass lenses that are intentionally prescribed with a greater amount of nearsightedness (myopia) correction than what is actually needed to provide clear distance vision. The purpose of using overminus lenses is to help alleviate symptoms of intermittent exotropia

Vision therapy

This involves a series of eye exercises and activities aimed at improving eye coordination and control. It can be beneficial for some individuals with intermittent exotropia.

Surgery

If other treatments are ineffective or the misalignment is persistent and causing significant visual impairment, surgical intervention may be considered.

Which Treatment is Best for Intermittent Exotropia?

Currently, there is no consensus on which therapy modality is the most effective for this condition. There have been a number of randomized clinical investigations of occlusion and over the minus lens that support their usage. Surgery is a common therapeutic option for patients with intermittent exotropia, although there is little evidence to back it up.

There is a scarcity of data from randomized clinical trials comparing the effects of surgical treatment versus observation alone. Furthermore, it is frequently noted that following surgery, the ailment has a high tendency to return, and a substantial percentage of patients require reoperation.

Unlike surgery, which tries to minimize the size of the deviation, vision therapy is primarily concerned with increasing exodeviation control. Visual skills that may aid in the regulation of exodeviation are developed by vision therapy. There have been a lot of studies that show vision therapy is effective for intermittent exotropia, but none of them used approved methods to assess exodeviation control.

”Vision therapy is primarily concerned with increasing exodeviation control, while the surgery tried to minimize the size of deviation.”

Read Ula’s Dtory about Intermittent Exotropia and AmblyoPlay

Ula’s daughter with intermittent exotropia condition

We’ve been using AmbloPlay for the last 6 months on a daily basis trying to improve our 4 years old daughter intermittent exotropia on both eyes. We can see a significant improvement and even a doctor said it must work even though he is skeptical about vision therapy. so we gonna keep up on using this great tool. Thank you to all who have invented this therapy!

Case Study: Vision Therapy for Intermittent Exotropia

Participants Overview

This was a chart review that was done in the past. From 2017/01 to 2018/12, all patients who received office-based vision therapy for intermittent exotropia in a private optometric clinic were evaluated.

Patients who got vision therapy were reevaluated every 5 therapy sessions, and only those who had had at least 5 sessions were studied. Visual acuity in each eye had to be correctable to 20/25 or better in all cases. Furthermore, intermittent exotropia patients with and without strabismus surgery were both included in the study.

Results of a study analysing vision therapy for intermittent exotropia

The results of this study suggest that in a private practice setting, office-based vergence/accommodative therapy was beneficial in improving the control of intermittent exotropia in both operated and unoperated patients. Furthermore, this study also indicates that the Office Control Score can be used in a private practice setting.

Several studies have found that vision therapy is useful in the treatment of intermittent exotropia. Previous research, on the other hand, typically included many criteria to assess the success of vision therapy. These criteria vary a lot between research, making it impossible to make meaningful comparisons.

What is more, it’s worth noting that there’s just one study of vision therapy in the literature that uses a stand-alone control ability outcome measure. Based on the frequency with which exodeviation was decompensated, the control capacity was graded as good, moderate, or poor in that study.

They argued that their treatment group, which received fusion exercises, improved in distance stereopsis, fusional vergence, and distant deviation control. However, it should be noted that their control ability assessment and grouping approach was not validated.

Conclusion

In conclusion, in a private practice setting, office-based vergence/accommodative therapy with home reinforcement significantly improved exodeviation control in both operated and un-operated intermittent exotropia patients. These cases highlight the potential benefits of vision therapy in managing intermittent exotropia. Therefore, when treating intermittent exotropia, eye care professionals should consider vision therapy.

Source: Ma, M. M. L., Kang, Y., Chen, C., Su, C., Tian, Z., & Le, M. (2020). Vision therapy for intermittent exotropia: A case series. Journal of Optometry. Published. https://doi.org/10.1016/j.optom.2020.05.006