Sunglasses are more of a fashion statement than a shield against sunshine. Nowadays, people pay much attention to their fashion function. The shape of sunglasses has something to do with their appearance. Most of us want to make them looks chic, so they always would like to wear sunglasses to style themselves. Any place that you find a person wearing sunglasses, it is just as possible to find a person not wearing one, and just as comfortable under the conditions. So, while in some cases they might round up on your face and end up offering you more of a shield against sunglight or dust, there are no strict lines drawn. The curvature of sunglasses, just as their straight and squarish look, always has an aesthetic appeal attached to it.