Thank you @Ursa and @BiancaK for the welcoming messages. It’s good to know others have taken that route.
About stereo vision, let me share my story as it may be useful to others. Sorry it’s a bit long, but the trick was autostereograms (you can skip to that part if you’re in a hurry). Disclaimer: I’ve done all of this without the supervision of an orthoptist (I have an appointment next week for an evaluation).
It all started after hearing of a study at McGill by Prof. Hess and his team (example of one of their publications) and reading Susan Barry’s book “How I fixed my gaze”. I felt comforted in the idea that amblyopia in adults is not a lost cause.
The McGill study made use of a modified Tetris game using blue/red 3D glasses (anaglyph) where one eye sees the falling blocks while the other sees the blocks that have already fallen.
I’ve reproduced this experiment for myself (for those who are interested, I can share my software).
I also made my custom exercises with text in which 1/3 of the words are seen by the left eye (blue), 1/3 by the right eye (red) and 1/3 by both eyes.
In both exercises (Tetris and text), what I noticed is that the image from the left (weak) eye was shifted slightly right and upwards compared to the right image. Practicing helped reduce the gap a bit, but it never locked in place, it was kind of floating. Also shapes are distorted: the left eye sees things a bit more squished vertically). I did these exercises for several weeks more than a year ago, then stopped for a while.
I also observed this offset in real life. Throughout my day, I often find myself closing my eyes in turn, and clearly see the shift taking place.
So… back to my breakthrough. As I was pondering where to start in my journey towards a better eyesight, I read again about amblyopia and ways to reduce it. I found some more advanced ways of helping both eyes to work together, including the use of 3D shutter glasses, but I haven’t tried that yet.
But then, exactly a week ago, when reading about stereo vision, I found a reference to autostereograms. You might remember the book “The Magic Eye” from the 90s. A 3D image pops out of a pseudo-random picture, when looked at in a certain way. Not everybody sees the 3D shapes, but I used to be able to do it as a teenager, and so I wondered if that was still the case (I found examples online).
And I was! But the interesting thing is: I felt something in my eyes, a discomfort at first, but I soon realized that my left (weak) eye was working hard. Some muscles were engaged in a way they usually aren’t. I focused on that feeling, and, after closing my eyes to go to sleep, I was able to reproduce it. That was Friday night.
The next day, my Tetris game with blue/red glasses was suddenly easy. Everything was aligned, not floating anymore. All I had to do was to actively engage my left eye, and I believe the Magic Eye pictures I had looked at the night before had allowed me to discover how to do it. To me it feels like how people describe how they discover active focus: you can’t explain how to raise and eyebrow, but once you know how to do it…
I spent a lot of time outdoors last weekend, and I was able to keep this focus (maybe I should call it “active coordination”) all the time. I even doubted I was able to turn it off. The images from both eyes were aligned ; sure, one of them was blurrier, because under-corrected, but at least there was not double vision. This was true for both near and far objects. I was able to read with both eyes engaged, and could appreciate a small improvement in depth perception.
Since then, I was able to improve my stereo vision further by using my newly acquired trial lens set (-1D in the left eye, and +1D in the right) for close-up reading. This is the highest quality of depth perception I remember experiencing!
Because I have an orthoptics appointment next week, I decided to not force it and let my left eye be lazy again for a few days, so I have a documented baseline before I resume my efforts.
I’ll report what comes out of the orthoptics appointment. Over the phone I got the feeling the doctor wasn’t too confident about the chances of reducing amblyopia in adults. Let’s see if I can change her mind.