Aspherical Intraocular Lens

Synonyms

Aberration free intraocular lenses

Definition

Aspheric intraocular lenses are defined as lenses that try to modify the spherical aberration of the optical system of the eye to achieve improved quality of vision. This is done by the modification of the curvature of at least one surface in an aspherical manner.

Basic Characteristics

Asphericity in IOL Optics

In IOLs, asphericity usually describes a lens with at least one nonspherical surface of usually rotational symmetric shape and continuously changing radii from center to periphery. An exception is any kind of toric aspheric IOL, which is not rotationally symmetric but still keeps up the same asphericity in each meridian, even with changing radii in the meridians. Asphericity is described by the Q factor, which characterizes different types of spherical, elliptic, or nonelliptic shapes. Q = 0 characterizes a spherical shape, Q > 0 an oblate ellipse, Q <0 but > − 1 a prolate ellipse, Q = −1 parabolic, and Q < −1 a hyperbolic...