Concerns of adult strabismics

I've been talking online with a lot of adults strabismics, and I've observed that there a few particular concerns and topics of discussion that come up quite often. They are:

• Are strabismics really able to gain stereovision through vision therapy? Or is it limited to very, very rare cases?
• Do alternating suppressors have an easier time gaining stereovision than constant, one-eye suppressors?
• Do strabismics undergoing vision therapy commonly develop permanent double vision?

In my limited experience observing other strabismics that come through the vision therapy office, I had my doubts about these questions. I've seen many strabby children start vision therapy, gain stereovision, graduate vision therapy, and leave. I've never noticed or heard of a difference between alternating suppressors and constant suppressors. And I've never seen anyone end up with permanent double vision. But again, my experience is very limited.

So yesterday I decided to ask my vision therapist for her thoughts. She's been doing vision therapy for 11 years (and also works 50+ hours per week), so I figure she has a lot of experience to draw upon.

Here are her responses to my questions. (Note: These responses are paraphrased and from my memory.)

• Are strabismics really able to gain stereovision through vision therapy? Or is it limited to very, very rare cases?

When I asked her this question, she pulled out her iPhone and showed me some before and after pictures of several young patients (and one adult). They were patients who came in with strabismus and eye turns, very clearly visible in the pictures. And in the "after" pictures, they had perfectly straight, lovely eyes. She told me that she could think of the names of 10 patients off the top of her head who had fixed their strabismus and gained stereovision.

She said that the majority of success stories were children with no history of eye surgery. She also said that she didn't measure the success of vision therapy only by stereovision. Even the people who don't gain full stereovision are helped greatly - they don't have double vision anymore, they can read and drive again, they can study again, they can get good grades again, they can see again.

• Do alternating suppressors have an easier time gaining stereovision than constant, one-eye suppressors?

She said that, from her perspective, she prefers to work with constant suppressors. Alternating suppressors are "professional switchers" - they focus on "getting the right answer" rather than using both eyes together to accomplish a vision therapy task. Basically, they cheat! She has to avoid certain vision therapy exercises with alternators, since they just switch their eyes back and forth until they figure out a way to cheat. She viewed alternating suppression as a hindrance to vision therapy. Alternating suppressors are always foiling her plans and thinking up smart ways to cheat on VT exercises.

She then remembered off the top of her head a recent constant suppressor / deep amblyope patient who had just gained stereovision.

•  Do strabismics undergoing vision therapy commonly develop permanent double vision?

She said that patients sometimes experience double vision during vision therapy when both of their eyes "turn on", but that's just part of the process and goes away later when both eyes are pointed in the same place. In 11 years of being a vision therapist, she has never seen anyone walk away from vision therapy with permanent double vision.