Thanks for this. I have just spent the last hour reading lots of useful stuff.

And as soon as Sabrina wakes up I have some eye tests to do on her.

I found that "There is some evidence of a familial tendency to the condition" and am wondering now if she doesn't have something similar, though less extreme. A confirmation of oculomotor nerve abnormalities in Sabrina would point towards this being a genetic inheritance.

Sinus inflammation is a possibility but I feel like this genetic connection is the more likely cause.