Eye size The horizontal measurement of the  lens on any frame at its widest part. This measurement is measured  in millimeters.

Bridge size - The width  between the lenses on a eyeglass/sunglass frame. Manufacturers  typically measure this width at the widest point between the two  lenses. This measurement is measured in  millimeters.

Temple size - The length of the  arm of the frame running from the hinge to the end that wraps behind  your ear. This measurement is measured in  millimeters.

B Measurement - The vertical  measurement of the lens on any frame at its highest part. This  measurement is measured in  millimeters.