There is no mention of sunglasses in the rulebook. The accepted ruling is that a pitcher is allowed to wear them if they are not reflective or distracting in any other way. Umpires are taught to be very careful about the pitcher conforming to the rules and regulations regarding uniforms and equipment. A pitcher cannot have any unessential and distracting thing on his body such as jewelry, adhesive tape, or a batting glove. So, if a team complained about a pair of sunglasses I would think the umpire would be compelled to ask the pitcher to remove them.