Why can plastic frames with the same bridge size feel different?

01 · BRIDGE NUMBER

The number does not describe the whole bridge shape

The bridge size in a conventional frame marking is generally based on the boxing-system DBL, or distance between lenses.

That one number does not tell you the actual internal width, height, curvature or contact depth where the nose meets the frame.

The same marked number can therefore produce a different nose fit.

DBL is useful for comparing frame dimensions, but it is not a measurement of the wearer’s nasal width. In the boxing system it describes the shortest distance between lenses, so bridge material thickness, inner curvature and contact depth still need separate evaluation.

02 · BRIDGE HEIGHT

Bridge height and position can differ even at the same marked size

One frame may place the internal bridge contact higher while another places it lower.

That changes where the frame sits on the nose and the position of the lenses in front of the eyes.

03 · INNER CURVE

The inner nose-contact surface can be completely different

Differences in roundness, flatness and side slope change the true contact area.

One frame may support broadly while another touches mainly at an edge.

Two frames can share the same DBL while one has a shallow inner curve and the other a deep one. That difference changes the real contact point, pressure distribution and wearing height, so the number is a screening dimension rather than a final fit verdict.

04 · FRAME THICKNESS

Bridge and front thickness also affect facial clearance

The thickness and projection of the inner bridge, along with front thickness and lens placement, can change the lens-to-face distance.

This is one reason lash or cheek interference can differ despite the same bridge number.

05 · FRAME POSITION

Temple geometry and front tilt change the result too

Even with similar bridge geometry, temple direction, pantoscopic tilt and overall front alignment can change the final wearing position.

The completed fit matters more than the bridge number alone.

Front tilt and the direction of the temples can place otherwise similar bridges differently on the face. Final selection should therefore combine nasal contact with eyelash and cheek clearance, vertex distance and the vertical position of the eyes within the lenses.

SOLUTION GUIDE

Solutions at a glance

GLANOS FITTING CHECK

GLANOS fitting check order

1. Front
   Check frame alignment.
2. Bridge
   Judge actual contact rather than the printed number.
3. Width
   Check side support.
4. Temple bend
   Finalize the wearing position.

CAUTION

Do not buy a different model online simply because the bridge number matches your old glasses

GLANOS EYEWEAR

There is a reason glasses feel uncomfortable.