So, if you don’t have a glasses prescription to start with, we recommend taking cm measurements and converting that to diopters, and ordering glasses to match.

We measure distance to blur from the eye.

Isn’t the resulting diopter calculation the strength of lens at the eye?

For higher prescriptions, wouldn’t vertex distance come into it and raise that value for a glasses prescription?

This doesn’t matter for anyone under around -4D, the math nets out to about the same and we’re aiming for normalized to be a bit weak anyway, but above that we’re getting into being a full quarter diopter off. Could we improve the accuracy of this measurement by compensating for vertex distance when ordering glasses? We still run into issues with accuracy of small measurements above -10D…