Related Experiment Video
Updated: Jun 18, 2026

Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter
Published on: September 16, 2025
A method of determining the refractive index of a prismatic lens
1jgb@netspace.net.au
Purpose:
A new method of measuring lens refractive index requiring immersion in solution and measuring lens power in air and in solution is extended. Prompted by a clinical need, the new method using lens power can be extended by applying it to prismatic power as well. This article provides a theoretical basis explaining why this can be done.
Methods:
The prismatic power of a prism is derived from first principles. Snell's Law and geometrical optics provide the framework for demonstrating the validity of the resulting formula.
Results:
The sameness in formula derived using lens power or prism is shown, both from a paraxial and non-paraxial optics perspective. The effect of varying lens material and amount of prism is considered.
Conclusions:
The prismatic method described provides a useful alternative method of determining the refractive index of any lens. In some cases, it may be the only method available. Practitioners should consider when each method will provide optimal results.
More Related Videos
Related Concept Videos
Focusing of Light in the Eye
Law of Rational Indices
Determination of Crystal Structures
Properties of Enantiomers and Optical Activity
Influence of Earth's Curvature and Atmospheric Refraction on Leveling
Deformations in a Transverse Cross Section
As the material stretches, it expands or contracts in orthogonal directions to the load. This phenomenon varies...

