Intraocular lenses having zone-by-zone step height control
A method and system provide an ophthalmic device. The ophthalmic device includes an ophthalmic lens having anterior surface, a posterior surface and at least one diffractive structure including a plurality of zones. The at least one diffractive structure is for at least one of the anterior surface and the posterior surface. Each zone includes at least one echelette having a least one step height. The step height(s) are individually optimized for each zone. To compensate chromatic aberration of eye from distance to a range of vision, a greater than 2π phase step height may be employed and the step height(s) folded by a phase, which is an integer multiple of two multiplied by π. Hence chromatic aberration of eye may be compensated to improve vision from distance to near.
1. A method for fabricating an intraocular lens (IOL) having at least one focal length, the method comprising:
designing at least one diffractive structure including a plurality of zones for incorporation into at least one of an anterior surface and a posterior surface of the intraocular lens, each of the plurality of zones including at least one echelette having at least one step height, the step of designing the at least one diffractive structure further comprising:
individually optimizing each zone of the plurality of zones to provide at least one optimized step height having at least one optimized phase in each zone of the plurality of zones; and
folding the at least one optimized step height in each zone of the plurality of zones by a phase to provide the at least one step height in each zone of the plurality of zones if the optimized step in each zone of the plurality of zones exceeds two multiplied by π, the phase being an integer multiple of two multiplied by π; and
fabricating the intraocular lens using the at least one step height of each zone of the plurality of zones for the at least one diffractive structures;
wherein, after folding the at least one optimized step height in each zone of the plurality of zones by a phase, the at least one step in each zone of the plurality of zones is not more than two multiplied by π to compensate for chromatic aberration for a range of vision;
wherein the at least one focal length is a plurality of focal lengths and wherein the step of individually optimizing each zone further includes individually optimizing each zone for at least a portion of the plurality of focal lengths.
2. The method of claim 1 wherein the at least one diffractive structure is incorporated into the anterior surface.
3. The method of claim 1 wherein the at least one diffractive structure is incorporated into the posterior surface.
4. The method of claim 1 wherein the step of individually optimizing each zone further includes individually optimizing each zone for a plurality of target positions.