Anna Wintour always wears sunglasses for several reasons. She has explained that the sunglasses are "incredibly useful because you avoid people knowing what you're thinking about" and that they help her when she's feeling tired or sleepy. Beyond practicality, she describes them as a "prop" that helps her see and not see, be seen and not be seen, serving as a kind of armor or shield. She has also mentioned that sunglasses provide privacy and a certain mystique, making them a signature and powerful part of her personal brand. Additionally, she once wore them due to illness and eye surgery, but they have since become a permanent part of her look and identity in the fashion world.
