Remember back when you watched The Matrix for the first time and ran down to the store to buy sunglasses and a trench coat? There were so many sunglass brands to choose from: Oakley, Ray-Ban, Revo, Vogue, DKNY, and if you must have only the best, $500 designer glasses from Prada and BVLGARI (which has that V-instead-of-a-U thing, so you know it's classy like ancient Rome).
Which was famous for its sunglasses.
The thing is, all of those are made by one manufacturer -- Luxottica. Starting off as a tiny Italian glasses company, Luxottica caught the 1980s fever (see Wall Street) and started buying every glasses-related company it could get its hands on, as well as talking pretty much every fashion designer into letting them make their sunglasses line.