LW (Lens Width) is the length of the glass measured horizontally over the widest part of the lens, and DBL (Distance Between Lenses) is the distance between the glasses measured at the nose bridge. All measurements are in millimeters. We use these measurements to find the CD (Centre Distance) of the frame i.e. the size of the frame.
In our example the LW (width of the glass lens) is 55 mm and DBL (distance between lenses) is 15 mm, which together adds up to 70 mm. This means that we end up with a 70 CD, which is equivalent to a size Large.
Find all the sizes on the chart below.
TL stands for Temple Length and describes the length of the frame’s temple (the arms which sit to the sides of the head and rest on the ears).
The size of this frame is 55/15 – 140 which is always printed on the inside of the temple.