Glossary N–Z

Still fluent. Keep going.

By James Stone

Issue #1 · Published Oct 19, 2026

Nose pads: The adjustable cushions on metal frames that carry the weight on your nose.
OD / OS: Prescription shorthand: OD is your right eye, OS your left. Latin, obviously.
Pantoscopic tilt: The slight forward tilt of the frame front, tuned so lenses sit at the right angle.
PD: Pupillary distance: the millimeters between your pupils. Get it right or nothing else matters.
Photochromic: Lenses that darken in sunlight and clear indoors. Transitions GEN S is the famous one.
Polarized: A filter that kills horizontal glare off water, roads, and hoods. Non-negotiable for drivers.
Polycarbonate: Impact-resistant lens plastic. The default for kids and sport.
Progressive: A no-line multifocal: distance to reading in one smooth gradient.
Rimless: Lenses mounted directly to temples and bridge, no frame around them. Maximum disappearing act.
Rx: Shorthand for prescription. Your lenses, your numbers.
Saddle bridge: A wide bridge that distributes weight across the nose. Comfort-first design.
Temple: The arm that runs to your ear. Holds the hinge's other half.
Trivex: Light, strong lens material like polycarbonate, with sharper optics.
UV protection: Blocking ultraviolet light. Non-negotiable in any lens worth wearing.
Vertex distance: The gap between your lens and your eye. Small number, big optical consequences.