Spherical and aspheric refer to the design of the
contact lenses’ surface. Spherical lenses are uniformly curved, while
aspheric lenses provide a gradient change of curvature across the
surface. Spherical lenses are generally used to correct basic cases of near and
farsightedness, and toric and multifocal lenses usually feature an aspheric
surface. Both of these lenses are made of silicone or silicone hydrogel to
provide optimum comfort and visual sharpness.
