Toric intraocular lens with modified power characteristics
View Patent ↗An intraocular lens for correcting or reducing the astigmatism of a cornea includes an optical element that has optical properties and characteristics that make it tolerant of rotational misalignment, when compared to a comparable lens having a uniform astigmatism orientation across its entire optical element, leading to more relaxed tolerances for a surgeon that implants the lens. The optical element of the toric ophthalmic lens has meridians associated therewith, including a high power meridian and a low power meridian orthogonal to the high power meridian. The optical element has at least one radially modulated meridian along which power monotonically varies with increasing radial position.
1. A tonic ophthalmic lens comprising an optical element, the optical element having meridians associated therewith, including a high power meridian and a low power meridian orthogonal to the high power meridian, the optical element having at least one radially modulated meridian along which power monotonically and strictly varies in a continuous manner with increasing radial position along the entire radially modulated meridian.
2. The toric ophthalmic lens of claim 1 , wherein the power along the at least one radially modulated meridian decreases with increasing radial position.
3. The tonic ophthalmic lens of claim 1 , wherein the power along the at least one radially modulated meridian increases with increasing radial position.
4. The tonic ophthalmic lens of claim 1 , wherein the power along the at least one radially modulated meridian decreases, with increasing radial position, to zero.
5. The toric ophthalmic lens of claim 4 , wherein the power along the at least one radially modulated meridian reaches zero at a radial position inside a periphery of the optical element.
6. The toric ophthalmic lens of claim 1 , further comprising a diffraction grating, wherein the diffraction grating provides a first focus point and a second focus point.
7. The tonic ophthalmic lens of claim 1 , wherein along the high power meridian, the integral of power times radius squared is equal to the nominal power times the area of a clear aperture of the optical element.
8. A tonic ophthalmic lens comprising an optical element, the optical element having meridians associated therewith, including a high power meridian and a low power meridian orthogonal to the high power meridian, the power varying with increasing radial position,
wherein along the high power meridian:
between an originating position and a respective first radial position, power equals a respective nominal power;
between the respective first radial position and a respective second radial position, power is greater than the respective nominal power; and
between the respective second radial position and a respective third radial position, power is less than the respective nominal power;
wherein the power between the originating position and the respective third radial position monotonically varies in a continuous manner, such that the power monotonically and strictly varies with increasing radial position along an entire length of the high power meridian.
9. The tonic ophthalmic lens of claim 8 , wherein between the respective first radial position and the respective second radial position, the power equals an overcorrection power.
10. The tonic ophthalmic lens of claim 9 , wherein the overcorrection power exceeds the nominal power by no more than 1.5 diopters.
11. The toric ophthalmic lens of claim 10 , wherein between the respective second radial position and the respective third radial position, power equals an undercorrection power.
12. The tonic ophthalmic lens of claim 11 , wherein the nominal power exceeds the undercorrection power by no more than 1.5 diopters.
13. The toric ophthalmic lens of claim 8 , wherein along the high power meridian, the integral of power times radius squared is equal to the nominal power times the area of a clear aperture of the optical element.
14. The toric ophthalmic lens of claim 8 , wherein the optical element comprises a diffraction grating.