UV protection is only the primary reason for wearing them.
An editor of Golf Digest says he is among the many golfers who don’t like wearing sunglasses while playing because they interfere with the game. But, he says, he wears them because there are several reasons beyond UV-protection for doing so – among them the possibility of a better game. “Prolonged squinting can increase tension,” he writes. “Anytime a muscle group stays in a contracted state for long periods, it tends to have a contagious affect on other muscles. You’ll find yourself gripping the club tighter and possibly restricting your body turn.”