On the back of spectacle frames, the figures such as 46 x 22 represent what?

The figures such as 46 x 22 on the back of spectacle frames typically represent the size of the lenses and the bridge width. The first number, which is 46 in this case, indicates the width of each lens in millimeters. The second number, which is 22, signifies the width of the bridge—the area that sits over the nose that connects the two lenses. This specification is crucial for ensuring the proper fit of the frames on the wearer's face, contributing to both comfort and optical performance. Understanding these measurements is essential for eyecare professionals when crafting or fitting prescription glasses, as they affect how the glasses sit and perform on the wearer’s face.