What it means and why
White light contains different wavelengths. A lens material may bend them by slightly different amounts; that separation is dispersion. The Abbe value describes this material property: a lower value generally indicates more dispersion. It is not a measurement of surface smoothness or prescription accuracy.
A wearer may notice coloured edges around a high-contrast object when looking away from the lens centre. Whether that is noticeable depends on power, gaze position, centration and the person, so the number alone cannot predict a complaint.
A worked example
Teaching scenario: lettering near the side of a computer display looks fringed, while central viewing is clearer. Mention the viewing direction and compare through the fitted lens centre. This is useful information for checking fit and material choice, not an online diagnosis of the cause.
What it does not tell you
A high Abbe value does not guarantee no glare, and an anti-reflective coating does not change the bulk material’s dispersion. They address different optical effects.
THINK IT THROUGHWill a different surface coating change the material’s Abbe value?
No. Compare dispersion as a material property and reflection reduction as a surface treatment.
Sources & reading notes
Page updated:
- ABDO · Single vision lens basics ↗ Professional body guidance
Explains terminology and dispensing practice; it is not a head-to-head product trial.
- ABDO · Lens materials and design (OA Corner 40) ↗ Professional body guidance
Explains terminology and dispensing practice; it is not a head-to-head product trial.