There is an interesting story about the birth of Ray Ban sunglasses. In 1923,an Air Force Lieutenant of American met with the trouble brought by strong sunlight https://sunglasses.li when driving a small plane across the Atlantic. After going back to base, he suffered from nausea, headache, and dizziness. Therefore, in 1930, Bausch 2, the gentleman-type sunglasses; 3, lady -type sunglasses.
The users on SFYH.com have made a definition on these three types of sunglasses that the gentleman-type sunglasses represents conservative and noble; lady-type sunglasses represents elegant and chic; sports sunglasses represents energetic and responsive.