Pang, Yi; Frantz, Kelly A.; Schlange, Darrell G.

Vision Therapy Management for Dissociated Horizontal Deviation

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Dissociated horizontal deviation (DHD), a rare subtype of strabismus, is a change in horizontal eye alignment that does not obey Hering’s law. The variation is unrelated to a change in accommodation and depends on which eye is fixating. Both esotropia (ET) and exotropia (XT) can manifest in the same patient with DHD. Surgery has been reported to manage DHD, but often a second or third surgery is necessary. We report two cases of DHD that were managed with vision therapy (VT).


Case Reports 

Case one: A 9-year-old girl presented for eye examination with her parents noting an eye drifting out. Cover test showed a DHD that varied from 15Δ left ET to 15Δ alternating XT. A 40Δ XT manifested when she was inattentive. Anti-suppression, vergence, accommodation, and oculomotility were addressed with VT. Upon completion of VT, binocular vision functions were normal except for appreciation of global stereopsis. No strabismus was observed during the examination. These findings were stable at a 7-month follow-up visit. Case two: A 40-year-old man presented for eye examination with the complaint of double vision and eye strain. Cover test revealed a DHD that varied from 5Δ ET to 15Δ XT, along with DVD. A 30 to 40Δ XT was observed during visual inattention. Antisuppression and vergence skills were addressed with VT. At the end of VT, most binocular vision functions were normal. No strabismus was observed on cover test. Follow-up examination 16 years later showed no strabismus by cover test, although XT manifested when he was inattentive.



In two DHD cases, control of eye alignment improved with VT. To the best of our knowledge, these are the first case reports to describe management of DHD with VT. Eye care practitioners should be aware that a long period of VT may be necessary to successfully manage DHD.


  • Vision therapy is well worth the response, time and effort. Our Son had a hard time focusing and writing neatly. After vision therapy Seth could complete a task in half the time if previously took. His abilities to focus improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.

    Amanda T.

  • Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

    Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.

    Alexa H.

  • Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

    He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

    It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

    Dr. McBryar , Kristen and John  are all marvelous and we would recommend them to anyone I only wish that we would have found them sooner!

    Charlotte M.

  • Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

    Thank you!

    Olivia C.

  • Seems much less frustrated with life

    Reads non-stop and fast

    Spelling abilities have been hugely improved

    Seems much more confident

    Thank You!!!

    Kelly O.



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