Traditional intraocular lenses have a spherical optical design, meaning the front surface is uniformly curved from the center of the lens to its periphery. This design does not mimic the shape of the natural lens inside the eye, which varies in curvature from center to periphery. In other words, the eye’s natural lens is aspheric (“not spherical”).
A spherical intraocular lens can induce minor optical imperfections called higher-order aberrations (HOAs), which can affect quality of vision, particularly in low-light conditions such as driving at night.
Premium aspheric IOLs, on the other hand, match more closely the shape and optical quality of the eye’s natural lens, and thereby can provide sharper vision — especially in low light conditions and for people with large pupil size.