They are regular or designer frames with lenses that carry no prescription so that they can be worn by anyone with normal vision, or by a person who is also wearing contacts.
"I've got a hot date tonight, I better go get myself a new pair of Fashion Goggles."
Actors and actresses often wear Fashion Goggles for movies, projects and photo shoots.
Clark Kent (Superman) always wears Fashion Goggles as to conceal his identity as a superhero.
"Those aren't the same glasses you had on yesterday."
"Yea, I don't actually need glasses, I just wear them."
"Ooooh, so you're just wearing Fashion Goggles"