Whoever said sunglasses needed to have obnoxiously colorful frames in order for them to be considered "retro" is dead wrong.
Yes, pink or red frames certainly are a trait of the "retro" style, but it is the shape of the frame that determines whether or not the sunglasses fit this category.
Sidenote: Neon green is not "retro," it's tacky and cheap looking. I don't care if it's Dior Limited Edition. Neon sunglasses are such a NO in my book.
You can go "retro" by sticking to black, and here are a few examples of how...