What should you know first?
Numbers such as 52-18-140 usually indicate lens width, bridge width and temple length in millimeters. They help describe frame dimensions, but matching numbers alone do not guarantee that a replacement temple, lens or entire frame will fit.
Reading the three numbers
In a common 52-18-140 marking, 52 refers to nominal lens width, 18 to bridge width and 140 to temple length. Manufacturers may include other model or color codes.
Where to find markings
Look inside the temples or near the bridge. Older frames may have faded or missing markings; photograph what is legible.
Why equal sizes can fit differently
Lens shape, bridge contour, frame curvature, hinge position and temple design all affect fit. Two frames with identical printed numbers can feel different.
What size means for replacement parts
A temple length is not a universal part identifier. Hinge type, attachment geometry and manufacturer model remain important.
What to send for an assessment
Include brand, model, size and clear photographs of both temples and the full front. Avoid ordering parts from the size numbers alone.
Common questions
Does 52-18-140 mean medium size?
Not necessarily. Fit depends on design and the wearer, not just the three measurements.
Can I replace an arm with any 140 mm temple?
No. The hinge and attachment must be compatible.
About this guide
Published by EyeglassesRepair.com to explain its VintageOptika-connected services. This is general eyewear-service information, not an individual optical diagnosis or a guarantee of repair availability. For request-specific answers, contact VintageOptika.