Sunglasses do not offer any bonus stats to your character. Like 护目镜, these do not cover the player's hair, allowing you to hide your helmet to show your hair. It can be noted that if you're inflicted with the 着火了！ or 诅咒地狱 减益, wearing the Sunglasses appears to lessen the particle effect on your character. This does not lower the amount of damage it does.
As an additional effect, while the player is wearing sunglasses, the sun will appear to be doing the same.