Refractive index: why prescription power alone is not enough

Comparing options

Compare materials with the same prescription and frame. Changing shape, diameter or minimum thickness at the same time prevents attributing differences solely to index.

Example question

For a −9.00 D prescription, also gather cylinder, axis, monocular PD, fitting height and frame shape and size. Sphere power alone does not select the best option.

Limit

There is no universal recommendation of 1.60, 1.67 or 1.74 based only on power. Final selection depends on available options and professional assessment.

References

• ZEISS — High index lenses

Related topics

• Lens materials: compare more than index
• Lens thickness: inputs needed for an estimate