It's safe,just like sunglasses.It's very fashion and looks good. But you should also choose good quality eyeglasses and best fit your face. Otherwise you will feel pressured on your nose and even cause headache when wearing them for a long time.
I think it is safe to wear this kind of glasses. Many people who don't have any vision problems will wear plano sunglasses to protect their eyes from the harmful UV rays. Maybe this kind of glasses is similar to the sunglasses lenses that they are available for people who don't have any vision problems.