glasses have lenses with an off-center base: the axis of the focal
centre is aligned with the focal centre of the eye so your eyes don’t
get tired and the curvature, which provides essential protection from
sunlight and insects, won’t cause any image distortion.
visibility even when it’s raining or the lenses are wet. The lenses are
treated to make them perfectly smooth so any drops of water simply
slide off, leaving the surface dry and free from water prisms.