Hello,
This is question I've had for 30 years. Maybe someone here knows the
answer.

In the 1970's I worked at a 'free clinic' for a couple of years. Part
of my job required that I use a microscope with two eyepieces. I found
it a very uncomfortable experience, but never understood why, until...
One day, after about 10 months or a year, the two two-dimensional
fields that I had been looking at all that time spontaneouly popped
together to become one three-dimensional field.  I was astounded! I ran
around the office asking if one circle was what everyone else saw, and
found out it was. I had had no idea that I was seeing what everyone
else was seeing.

My question: Was my experience of seeing two circles for so long,
unusual? If so, does it mean anything?

Thank you for any illumination anyone can provide.