Hi MG_Kat33,

I have recently developed permanent ptosis in one eye but don't have an overarching diagnosis yet.

Since I've looked into this after wondering the same thing, I thought I'd mention that anything that compresses the related nerve(s) can cause it--tumor (eg, pancoast tumor), edema, etc. It can also be caused by respiratory problems, infection, nerve damage caused by diabetes. It also can be caused by muscle weakness rather than nerves.

Mine came on suddenly in occurrence with neurological and other symptoms, and now I look 10 years older than I did before. Sorry you have this too.