What eye disease/condition is this?!

I know someone who's left eye looks very different from her right one. Her eyes are blue, but where the right one is just a normal shade of blue the left is a daker, deeper blue. The colors look normal, they just don't match. She also rubs it a lot, it seems irritating. There also a red vain next to her iris that looks puffy. Her eye doesn't look ugly or scary, but it does look uncomfortable. I think her eye has had problems her whole life, she once mentioned she got surgery to correct double vision. I have no clue if she can even see out of it anymore. It moves in sync with her right eye, but moves as though it's weaker. Sorry I can't be more descriptive, I don't know her well enough to ask. Just curious.