spectacle frame markings

spectacle frame markings 

Numbers shown on a spectacle frame. They are usually the eyesize, the distance between lenses and the side length. Metal frames may also indicate the amount of gold (if any) found in the frame (e.g. 12 k meaning that the material is one-half gold and one-half of another metal). Example: 52/22 on the front of the frame means that the eyesize is 52 mm and the DBL is 22 mm, and 140 on the side means that the total length of the side is 140 mm. See distance between lenses; eyesize; side.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann