DISTANCE DOMINANT INTRAOCULAR LENS
An intraocular lens includes a base refractive structure having anterior and posterior surfaces that are shaped for producing a first optical power and a diffractive structure formed in one of the surfaces of the base refractive structure including overlapping first and second diffractive patterns over a common aperture for producing second and third optical powers. The second optical power is an uneven division of the third optical power. The first and second diffractive patterns have respective step heights that are separately varied as a function of radial distance from the optical axis over the common aperture.
1 . An intraocular lens comprising:
a base refractive structure having anterior and posterior surfaces that are shaped for producing a first optical power;
a diffractive structure formed in one of the surfaces of the base refractive structure including overlapping first and second diffractive patterns over a common aperture for producing second and third optical powers; and
the second optical power being an uneven division of the third optical power;
wherein the first and second diffractive patterns convey the first optical power through zero order diffraction for forming a distance focus;
the first and second diffractive patterns provide for producing the second and third optical powers through a first order diffraction for forming in combination with the first optical power respective intermediate and near foci; and
the diffractive structure is centered about an optical axis of the base refractive structure, and the first and second diffractive patterns have step heights configured to be separately varied such that the distance focus will receive an increasing portion of optical energy transmitted through the common aperture as a function of radial distance from the optical axis, and the increasing portion of the optical energy will be derived more from a corresponding decrease in the optical energy received by the near focus than a corresponding decrease in the optical energy received by the intermediate focus.
2 . The intraocular lens of claim 1 in which:
the first and second diffractive patterns have non-harmonic periodicities so that a second order diffraction through the first diffractive pattern produces a focus that is slightly offset from the near focus for extending an effective depth of the near focus.
3 . (canceled)
4 . The intraocular lens of claim 1 in which the step heights of the second diffractive pattern are varied more than the step heights of the first diffractive pattern as a function of the radial distance from the optical axis.
5 . (canceled)
6 . The intraocular lens of claim 1 in which the step heights are varied as functions of their radial distance from the optical axis, and the functions differ over different ranges of the radial distance.
7 . The intraocular lens of claim 6 in which the step heights of at least one of the diffraction patterns vary in a non-progressive manner with the radial distance.
8 . An intraocular lens comprising:
a base refractive structure having anterior and posterior surfaces that are shaped for producing a first optical power that directs incident light through a distance focus;
a diffractive structure formed in one of the surfaces of the base refractive structure over a common aperture for producing second and third optical powers that in combination with the first optical power direct incident light through respective intermediate and near foci;
the diffractive structure including a first diffractive pattern for producing the second optical power through a first order diffraction;
the diffractive structure including a second diffractive pattern for producing the third optical power through a first order diffraction; and
the first and second diffraction patterns being superimposed over the common aperture and having non-harmonic periodicities so that a second order diffraction through the first diffractive pattern extends the focal depth of the near focus;
wherein the diffractive structure is centered about an optical axis of the base refractive structure, and the first and second diffractive patterns have step heights configured to be separately varied such that the distance focus will receive an increasing portion of optical energy transmitted through the common aperture as a function of radial distance from the optical axis, and the increasing portion of the optical energy will be derived more from a corresponding decrease in the optical energy received by the near focus than a corresponding decrease in the optical energy received by the intermediate focus.
9 . (canceled)
10 . The intraocular lens of claim 8 in which:
the step heights of the second diffractive pattern are varied more than the step heights of the first diffractive pattern as a function of the radial distance from the optical axis.
11 . The intraocular lens of claim 10 in which the step heights are varied as functions of their radial distance from the optical axis, and the functions differ over different ranges of the radial distance.
12 . The intraocular lens of claim 11 in which the step heights of at least one of the diffraction patterns vary in a non-progressive manner with the radial distance.
13 . The intraocular lens of claim 8 in which the second optical power contributed by the first diffractive pattern is approximately 1.6 diopters and the third optical power contributed by the second diffractive pattern is approximately 3.1 diopters.
14 . The intraocular lens of claim 8 , wherein two different apodization functions are applied over different radial distances from the optical axis for varying the step heights of the first and second diffraction patterns as a function of radial distance.
15 . The intraocular lens of claim 1 , wherein two different apodization functions are applied over different radial distances from the optical axis for varying the step heights of the first and second diffraction patterns as a function of radial distance.