Multifocal ophthalmic lenses and related methods
A multifocal ophthalmic lens wherein a first surface of the lens is shaped to form a surface power map and a second surface of the lens is shaped to form a second surface power map. The first surface power map and the second surface power map together form a lens power map. The first surface power map, the second surface power map, or the lens power map comprises a spiral. The spiral has a variation across at least a portion of the lens. Methods of making and using such lenses are also provided.
1. A multifocal ophthalmic lens, wherein:
a first surface of the lens is shaped to form a first surface power map;
a second surface of the lens is shaped to form a second surface power map;
the first and second surface power maps together form a lens power map;
the first surface power map, the second surface power map, or the lens power map comprises a spiral, the spiral having a variation across at least a portion of the lens, wherein the spiral has a first periodic component, in a radial direction extending outwards from the centre of the portion, wherein the period of the first periodic component changes according to radial distance from the centre of the portion of the lens, and wherein the spiral has a second periodic component, with a constant period, in an azimuthal direction about the centre of the portion.
2. The multifocal ophthalmic lens according to claim 1 , wherein the spiral has two arms.
3. The multifocal ophthalmic lens according to claim 2 , wherein the spiral has more than two arms.
4. The multifocal ophthalmic lens according to claim 1 , wherein one or both of the first and second periodic components are of constant magnitude across the portion.
5. The multifocal ophthalmic lens according to claim 1 , wherein:
a peak power of each arm of the spiral does not vary with radial distance from the centre of the portion.
6. The multifocal ophthalmic lens according to claim 1 , wherein a magnitude of the periodic components changes according to one or both of: a radial distance from the centre of the portion and an azimuthal position about the centre of the portion.
7. The multifocal ophthalmic lens according to claim 6 , wherein a peak power of one or more arms of the spiral varies according to one or both of: a radial distance from the centre of the portion and an azimuthal position about the centre of the portion.
8. The multifocal ophthalmic lens according to claim 1 , wherein the power across the first surface power map and/or the power across the second surface power map varies smoothly across the portion.
9. The multifocal ophthalmic lens according to claim 1 , wherein the first and second periodic components vary as one of: a square wave, a sinusoid, and a rounded square wave.
10. The multifocal ophthalmic lens according to claim 1 , wherein the spiral is formed entirely on the first surface.
11. The multifocal ophthalmic lens according to claim 10 , wherein the lens is a contact lens, wherein the first surface comprises an outer surface of the contact lens and the second surface comprises an inner surface of the contact lens.
12. The multifocal ophthalmic lens according to claim 1 , wherein the portion of the lens corresponds to the optic zone of the lens, wherein the lens is a contact lens or an intraocular lens, and wherein the lens comprises a peripheral zone surrounding the optics zone, the peripheral zone providing no additional focusing or vision correction.
13. The multifocal ophthalmic lens according to claim 1 , wherein the lens is a spectacle lens, and wherein the first surface is shaped across the whole of the lens to form the first surface power map.
14. The multifocal ophthalmic lens according to claim 1 , wherein:
the portion of the lens comprises a central region and an outer region, the outer region surrounding the central region;
the lens power map within the outer region comprises the spiral; and
the lens power map does not vary periodically within the central region.
15. The multifocal ophthalmic lens according to claim 1 , wherein each arm of the spiral extends from the centre of the portion of the lens to the periphery of the portion.
16. The multifocal ophthalmic lens according to claim 1 , wherein the first periodic component has a period of greater than 100 microns.
17. A method of manufacturing a multifocal ophthalmic lens, the method comprising:
operating a lathe to shape a first surface of one of: a lens, a mould for a lens, or an insert for manufacturing a mould for a lens to form a first surface power map;
operating a lathe to shape a second surface of the lens, mould, or insert to form a second surface power map;
wherein:
the combination of the first and second surface power maps forms a lens power map;
the first surface power map, the second surface power map, or the lens power map comprises a spiral, the spiral having a variation across at least a portion of the lens, mould or insert, wherein the spiral has a first periodic component, in a radial direction extending outwards from the centre of the portion, wherein the period of the first periodic component changes according to radial distance from the centre of the portion of the lens, and wherein the spiral has a second periodic component, with a constant period, in an azimuthal direction about the centre of the portion.
18. A method of improving vision of a person, the method comprising:
providing a multifocal ophthalmic lens according to claim 1 to a person in need of improved vision.