Ophthalmic lenses and methods relating thereto
An ophthalmic lens ( 101 ), methods of manufacturing such a lens ( 101 ), and methods of designing such a lens ( 101 ) are described. The lens ( 101 ) includes an optic zone ( 103 ) centred on an optical axis ( 102 ) and a peripheral zone ( 105 ) surrounding the optic zone ( 103 ). Within the optic zone ( 103 ), along a first meridian ( 107 a ), the lens ( 101 ) has a first radial power profile that varies continuously in a first radial direction from the optical axis ( 102 ) to the peripheral zone ( 105 ). Along a second, different meridian ( 107 b ), the lens has a second, different radial curvature power profile that varies continuously in a second radial direction from the optical axis ( 102 ) to the peripheral zone.
1. An ophthalmic lens, the lens including an optic zone centred on an optical axis, and a peripheral zone surrounding the optic zone, wherein within the optic zone, along each meridian in a first set of meridians, the lens has a first radial curvature power profile that varies continuously in a first radial direction from the optical axis to the peripheral zone, and along each meridian in a second, different set of meridians, the lens has a second, different radial curvature power profile that varies continuously in a second radial direction from the optical axis to the peripheral zone, wherein the first radial curvature power profile has an opposite shape to the second radial curvature power profile, wherein meridians from the first set of meridians and meridians from the second set of meridians form an alternating pattern around the lens, and wherein the angular spacing between each meridian in the first set of meridians is less than 5 degrees.
2. The ophthalmic lens according to claim 1 , wherein the first curvature power profile has a first average radial curvature power value measured along each meridian in the first set of meridians and the second radial curvature power profile has a second, different average radial curvature power value measured along each meridian in the second set of meridians.
3. The ophthalmic lens according to claim 1 , wherein the first curvature power profile has a first average radial curvature power value measured along each meridian in the first set of meridians and the second radial curvature power profile also has the first average radial curvature power value, measured along each meridian in the second set of meridians, and wherein the first radial curvature power profile has a different shape to the second radial curvature power profile.
4. The ophthalmic lens according to claim 1 , wherein at the optical axis, at least one of the first radial curvature power profile and the second radial curvature power profile provides a distance power of between +0.5 and −25.0 D.
5. The ophthalmic lens according to claim 1 , wherein at the optical axis, at least one of the first radial curvature power profile and the second radial curvature power profile provides a near power of between +0.5 and +25.0 D.
6. The ophthalmic lens according to claim 1 , wherein at the optical axis, the first radial curvature power profile or the second radial curvature power profile provides a distance power, and the other of the first curvature power profile and the second curvature power profile provides a near power.
7. The ophthalmic lens according to claim 1 , wherein at the optical axis, the first radial curvature power profile and the second radial curvature power profile have the same value, and at a boundary between the optic zone and the peripheral zone, the first radial curvature power profile and the second radial curvature power profile have different values.
8. The ophthalmic lens according to claim 1 , wherein one of the first curvature power profile and the second curvature power profile increases monotonically in radial curvature power with increasing radial distance from the optical axis, and the other of the first curvature power profile and the second curvature power profile decreases monotonically in radial curvature power with increasing radial distance from the optical axis.
9. The ophthalmic lens according to claim 1 , wherein one of the first curvature power profile and the second curvature power profile includes at least one peak at a first radial distance from the optical axis of the lens, and the other of the first curvature power profile and the second curvature power profile includes at least one trough at the first radial distance from the optical axis of the lens.
10. The ophthalmic lens according to claim 1 , wherein the first curvature power profile has a peak in radial curvature power at a first radial distance from the optical axis, and the second curvature power profile has a peak in radial curvature power at a second, different distance from the optical axis.
11. The ophthalmic lens according to claim 1 , wherein the first curvature power profile and/or the second curvature power profile span a power range of at least 5.0 D.
12. The ophthalmic lens according to claim 1 , wherein the angular spacing between a meridian from the first set of meridians and an adjacent meridian from the second set of meridians is less than 1°.
13. The ophthalmic lens according to claim 1 , wherein along at least one further meridian in the optic zone, the radial curvature power varies with a third radial power profile that is different to the second curvature power profile and the first curvature power profile.
14. The ophthalmic lens according to claim 1 , wherein the radial curvature power of the optic zone results from a curvature of an anterior surface of the lens.
15. The ophthalmic lens according to claim 1 , wherein the lens is a contact lens.
16. The ophthalmic lens according to claim 1 , wherein the lens is a spectacle lens.
17. A method of manufacturing an ophthalmic lens, wherein the method comprises forming a lens according to claim 1 .
18. A method of designing the ophthalmic lens according to claim 1 , the method comprising:
selecting a first average radial curvature power value;
selecting a second, different average radial curvature power value;
designing a first curvature power profile that gives rise to the first average radial curvature power value;
designing a second curvature power profile that gives rise to the second average radial curvature power value; and
designing an optic zone for the lens, wherein the optic zone comprises a first set of meridians having the first curvature power profile and a second set of meridians having the second curvature power profile, wherein the first radial curvature power profile has an opposite shape to the second radial curvature power profile, wherein meridians from the first set of meridians and meridians from the second set of meridians form an alternating pattern around the lens, and wherein the angular spacing between each meridian in the first set of meridians is less than 5 degrees.