Angelina Jolie underwent secret laser surgery because she's "very short-sighted" and "didn't want to wear glasses".

The 49-year-old Hollywood actress has admitted she had the operation because she wore spectacles when she was young and she was worried about it impacting her acting career because would have trouble seeing when she was on stage and reading her lines.

She told Vogue Mexico: "One thing that very few people know about me is that I'm short-sighted, so when I was young I wore glasses and then I had laser surgery.

"It wasn't out of vanity, I just didn't want to wear glasses ... On stage I would probably have trouble seeing the person across the stage or reading things."

Angelina added of her eyesight trouble: "I think it puts you in a place where you're a little bit more isolated. You're not sure of the expression of the person across the room, you're not sure of the world around you in the same way that someone who can see perfectly can."

It comes after Angelina opened up about how having a successful movie career had a negative impact on her social life revealing she only has a few close friendships.

She told The Hollywood Reporter: "I don't really have those kinds of relationships. Maybe it's losing your parent young. Maybe it's working. Maybe it's being somebody who's been betrayed a lot.

"I don't have a lot of those warm, close relationships as much that I lean on. But I have a few, and a few is enough."

The actress - who is mother to Maddox, 23, Zahara, 19, Shiloh, 18, Pax, 20, Knox, 16, and Vivienne, 16 - added: "If somebody wants to watch bad TV and order Thai food, I'm the first one to put the fuzzy socks on and sit next to them. I like to be with people I love.

"I'm not somebody begging to be alone. I'm not that person that feels like: 'Oh, I wish I could just be alone so I could have my guilty pleasures.'

"Because usually my guilty pleasure is being with somebody. I love doing something that makes them happy. That really does make me happy."