Atoric design is currently most popular in the market. Whether the front surface of an atoric lens is spherical or aspheric, the lens back surface always provides the correction for astigmatism, a type of aspheric surface that is atoric, not topic. 

    A problem will appear while the spectacle lens used to correct the off-axis optics of a spherocylinder lens，only one base curve is available to correct field-of-view errors, yet there are two meridians of different power, and each meridian has its own sagittal and tangential errors. The lens designer must compromise, choosing a base curve that minimizes a blur value, a weighted average of the errors for each meridian. The atoric back surface has two principal meridians, as does a standard toric surface, but each principal meridian of an atoric surface has a noncircular cross-sectional shape.

    the finished atoric lens has a back surface that is a complex combination of two different aspheric curves. Atoric lenses are flatter, thinner, and lighter than spherical lenses of the same material and power, but the primary reason to use an atoric lens design is to improve off-axis image quality for sphero-cylinder lenses. The off-axis imagequality of an atoric lens can be better than that of a well-designed spherical or aspheric lens.