Frame size is determined by the three key measurements found inside the frame arm: lens width (from 31-60mm), bridge width (from 12-31mm), and arm length (from 115-155mm).
Your lens height (mm)
31
Lens height is essential for multifocal prescriptions, such as Progressives, which require a minimum measurement of 28-30mm. They are also recommended for Rx sunglasses.
