I know what you're going through, because my father is a diabetic and the nerves in his eyes are damaged from his diabetes and he currently not open them without immense pain and seeing double/tripple vision
They said it is possible it will heal itself in weeks/months/years and it's possible that it won't heal at all
It's always difficult to see a loved one struggling
I do hope she can make it to your wedding, that would be a great memory to send her off on
I'll send a prayer!