Eyewear glossary: frame and lens terms
Use this glossary to interpret common listing fields, spot missing information and know which terms need a retailer or optician to confirm.
Editorial notice: This guide is independent editorial research, not a product recommendation or ranking. The links on this page are not affiliate links, and PowderedPurple does not earn commission from them. Some PowderedPurple product profiles it links to carry clearly disclosed paid links to the retailer.
How this guide is built: Definitions describe common eyewear terminology and retailer fields. Listings use inconsistent labels and may omit measurements. This page does not provide a personal fitting or eye-care assessment.
Frame measurements
- Lens width or eye size
- The horizontal width of one lens opening, usually stated in millimetres. It is not the total width of the frame front.
- Bridge width
- The distance between the two lens openings at the bridge area. A number alone cannot show how a bridge will contact a particular nose.
- Temple length
- The stated length of one side arm. The curve and adjustment of the arm also affect how the frame sits.
- Lens height
- The vertical height of the lens opening. It can matter when comparing coverage and when an optician checks a prescription lens design.
- Frame-front width
- The overall horizontal width across the front of the frame. A listing may not supply it; do not calculate it from lens width and bridge width unless the manufacturer explicitly defines that method.
- Frame size code
- A sequence such as 50–20–140 commonly means lens width, bridge width and temple length in millimetres. Confirm the seller’s key and where the measurements were taken.
ABDO notes that frames with the same printed measurements can fit differently. Compare a pair you already wear, and use a dispensing optician for an individual fit check. Read the step-by-step measurement guide.
Fit and prescription terms
- Pupillary distance (PD)
- The distance between the pupils, measured for lens positioning. It is not the same as lens width or bridge width.
- Optical centre
- The lens point aligned with the wearer’s visual axis for the prescribed lens. Positioning and measurements should be checked by a qualified eye-care professional.
- Nose pads
- Separate supports, commonly adjustable on many metal frames, that contact the nose. Their position and contact can affect stability and pressure.
- Bridge fit
- How the bridge area rests on the nose. Frame material and bridge design affect contact; a product photo cannot establish an individual fit.
- Temple fit
- How the side arms run along the head and curve behind the ears. Pinching, slipping or pressure can require adjustment.
- Progressive or varifocal lens
- A lens design with zones for more than one viewing distance. The usable lens depth and fitting measurements should be confirmed with an optician.
Lens and feature terms
- Polarised
- A filter feature that reduces certain reflected glare. It does not state a UV-protection level; check the maker’s UV specification separately. See polarised vs non-polarised sunglasses.
- Lens tint
- The visible colour or darkness of a lens. Tint by itself does not confirm how much ultraviolet radiation the lens blocks.
- UV protection
- A product claim about blocking ultraviolet radiation. Look for a clearly stated, verifiable specification from the manufacturer or seller; do not infer protection from lens colour or a mirror coating. The American Optometric Association describes UV protection as separate from visible appearance.
- Lens material
- The material used for the lens. It is separate from the frame material and can affect properties such as weight and impact resistance.
- Frame material
- The material listed for the frame, such as acetate, metal or plastic. Broad labels do not identify the exact alloy, polymer blend or construction unless the source says so.
- Colourway
- A named or coded combination of frame and lens colours. Similar model names can refer to different colourways or lens features; verify the exact code.
Product feeds may contain an absent value rather than an explicit “no.” PowderedPurple marks unpublished fields as unknown and does not infer UV protection, bridge fit or frame shape from an image.
Related eyewear research
Editorial status
- Author
- PowderedPurple Editorial Team
- Responsible publisher
- PowderedPurple (Pty) Ltd
- Last reviewed
- Next scheduled review
- Hands-on testing
- None claimed. This guide uses public professional guidance and explains its limits.
- Monetisation
- Editorial only. This page carries no affiliate links.
- Corrections history
- Corrections are logged by PowderedPurple (Pty) Ltd. View the corrections record or email info@powderedpurple.com.
Sources
Public sources checked on 25 September 2026. Definitions are simplified for shopping research; use the manufacturer’s specification and an optician for individual lens or fit decisions.