Which type of lenses do the traditional rules of base curve selection not accurately apply to?

The traditional rules of base curve selection primarily rely on the assumption that lenses have a spherical shape and that the curvature affects vision and fitting in predictable ways. Aspheric lenses, however, are designed with a more complex curvature than simple spherical lenses. This means their shape can vary across the surface, allowing for a thinner profile and improved optical performance, particularly in reducing spherical aberrations.

Because of this variability in curvature, the straightforward application of base curve rules does not hold true. The aspheric design aims to provide better visual quality and comfort, especially for those with higher prescriptions, which is why traditional fitting guidelines may not be applicable. The unique properties of aspheric lenses require a more individualized approach to base curve selection, taking into account not just the lens power but also the specific visual needs of the wearer.