What is more important in practical terms…the actual diopter ratio between the right and left eyeglass lenses (e.g. 1 : 0.9375), or the diopter difference between them (e.g. 0.25D)?
The actual ratio will never be the same for both differentials and normalized, since only 0.25 D increments are used. You’d need custom free form lenses in order to get them equal.
The diopter difference though, can be made equal easily.
Which one are we referring to when we casually talk about equal diopter ratios? The diopter difference, right?