Disclosed is a method of designing a soft
contact lens, the method comprising the steps of: (a) measuring or defining a
wavefront generated by passage of light through a selected eye and using the
wavefront to generate a computer model of the optical characteristics of the selected eye; (b) measuring or defining the
topography of the
cornea of the selected eye; (c) incorporating into the computer model a soft
contact lens, the posterior surface
topography of which is defined by the
topography of the
cornea, offset by an arbitrary amount intended to represent the tear
layer thickness of the selected eye, said lens having a defined thickness at a selected locus on the
anterior surface; (d) calculating a desired topography for the
anterior surface of the lens such that the
wavefront will be corrected to assume a desired pattern (for example, preferably planar, the plane of which is perpendicular to the
optical axis of the lens) when passing through the computer model eye / lens combination; (e) remodelling the lens off-eye by adapting the posterior topography of the lens to a desired posterior topography to be manufactured; and (f) recalculating a modified anterior topography required as a result of adapting the posterior topography, the modified anterior topography being intended to preserve the desired wavefront pattern defined in (d) when the lens is in situ on the selected eye.