Curved sunglasses lack optical power because their parallel surfaces do not create a significant difference in curvature, which is necessary for lens functionality. While they may slightly distort light, the effect is minimal, similar to looking through a window. Prescription sunglasses are an exception, as they are designed with varying curvature to correct vision. The discussion highlights that only extremely thick and curved glass can distort images, but they do not function like traditional lenses. Overall, the design of standard curved sunglasses does not provide the necessary optical properties to enhance vision.