Vision Therapy Research: Developing Stereopsis in Strabismus Through Perceptual Learning


I’m rushing to share with you an important study just published in the Proceedings of the National Academy of Sciences by optometric researchers Ding and Levi on the Recovery of Stereopsis Through Perceptual Learning in Adults with Abnormal Binocular Vision.

This research is noteworthy for many reasons, not the least of which is the framing of its hypotheses and conclusions in the context of Sue Barry’s trailblazing experiences and book, and her vision therapy under the guidance of the developmental optometrist Dr. Theresa Ruggiero.  I’ll have more to say about this landmark paper.

– Leonard J. Press, O.D., FCOVD, FAAO

16 thoughts on “Vision Therapy Research: Developing Stereopsis in Strabismus Through Perceptual Learning

  1. Thanks for the heads up-I see that Dennis Levi was one of the authors. Also good to get more research to go with the patient success stories!

  2. My pleasure, Dr. Scott. Levi has done excellent work in the field. In fact, he’s among – if not the leading – researcher in the world on amblyopia/strabismus. That insures this will be taken seriously in the vision science community. Dennis is Dean of UC Berkeley Optometry, so it should open an eye or two there. Nor would it hurt if this pried open the minds of ophthalmologists who continue to blather about critical periods and VT being a waste of time, thereby misinforming patients and depriving them the opportunity for quality of life improvements.

    • You’re welcome Robert. I suspect they’ll follow a path that will proceed from ignoring it, to qualifying it, to claiming they knew it all along, to “that’s why we need to do surgery as early as possible”. “Ha-le-vie” they should acknowledge we have something positive to contribute here.

    • I head back from the authors, and three of the four subjects with strabismus had prior surgery, Two of those three were congenital esotropes, with one having had two surgeries (at 6 mos. old and at 6 yrs old) and the other having had surgery at 18 mos.old. It’s worth noting that despite having relatively early surgery, neither developed stereopsis prior to receiving the therapy protocol associated with this research.

      • Thank you for additional info. Thats great news, but still I wonder if there is any hope (regarding stereopsis) for “late aligned” (lets say after 5yo) congenitial esotropes like me…

      • Apparently yes. If you look at the experiences of Sue Barry, which this research paper cites as the impetus for the study, even though her third and final surgery was at age 7, she experienced no binocular stereopsis until she undertook vision therapy at the age of 48. So the fact that someone is cosmetically aligned doesn’t insure that they will have any meaningful stereopsis any more than the fact that one isn’t cosmetically aligned negates the opportunity to develop stereopsis if one is “late aligned”.

    • Correct, Irwin, though his talk at the COVD meeting summarized his work on amblyopia in the context of perceptual learning/neuroplasticity in adulthood (rstb.royalsocietypublishing.org/content/364/1515/399.full.pdf), whereas this work centers on strabismus. Thanks as always for reading and commenting!

  3. Hello everyone!
    I want to ask something. I have had strabismus from early childhood, from as long as i remember. It was left untreated (no patching, co surgery, no glasses). I’m now 24 years old, and literally blind in my left eye (20/200 Snellen, even worse). I want to ask if there is a way to restore binocular vision in my case?
    I recently read about stereopsis recovery. Is that applicable to my case?
    Please respond.
    Thanks you

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