Intraocular lens
View Patent ↗A vision correction arrangement is described in which a lens system having variable optical power varies in dependence on the orientation of the user's eye. The vision correction arrangement may be embodied as an intraocular lens implant, or an extraocular device such as spectacles. The intraocular lens implant comprises a fixed lens element ( 11 ) and a movable lens ( 12 ) element sensitive to the orientation of the eye, so that the optical power of the intraocular lens implant is increased when the user looks downward, and returns to a reduced optical power condition when the user's eye returns to a horizontal gaze. The fixed lens element may have a convex rear surface and a concave front surface, and the second lens element may be pivotally mounted in front of the first lens element, so that downward inclination of the eye causes the second lens element to swing away from the fixed lens element.
1. An intraocular lens implant comprising:
an optical combination of a first lens element and a second lens element;
securing means to fix the first lens element relative to a lens capsule with a front surface directed towards the iris of the eye; and
mounting means to mount the second lens element for pivoting movement under gravity between a first position in which the second lens is adjacent the front surface of the first lens and the optical combination has a first optical power, and a second position in which the second lens is spaced from the first lens and the optical combination has a second optical power greater than the first optical power;
wherein the second lens element has an asymmetric “teardrop” or “pear” shape with a thinner region at its upper part, and the arrangement being such that directing the front surface of the first lens element downwardly causes the second lens element to move to the second position, and directing the front surface of the first lens element horizontally or upwardly causes the second lens element to move to the first position.
2. An intraocular implant according to claim 1 , wherein the second lens element is pivotally suspended adjacent the front surface of the first lens element.
3. An intraocular implant according to claim 1 , wherein the front surface of the second lens element is convex.
4. An intraocular implant according to claim 1 , wherein the second lens element is circular in cross-section in planes perpendicular to a major dimension of the teardrop.
5. An intraocular implant according to claim 1 , wherein the front surface of the first lens element comprises a concave surface portion, and the adjacent surface of the second lens element is convex and substantially corresponds in form to the concave surface portion of the first lens element.
6. An intraocular implant according to claim 1 , wherein the surfaces of the first and second lens elements are configured such that the optical power of the optical combination is increased as the lenses are moved apart.
7. An intraocular implant according to claim 1 , wherein the rear surface of the fixed lens is formed with a ridge substantially surrounding the central region of the rear surface.
8. An intraocular implant according to claim 7 , wherein the ridge is an annular ridge presenting a radially outer surface substantially perpendicular to the surface of the fixed lens.
9. An intraocular implant according to claim 7 , wherein the ridge includes one or more circumferential discontinuities or gaps.
10. An intraocular implant according to claim 7 , further comprising a drain passage penetrating through the fixed part of the implant from the front surface of the first lens element to the rear surface of the first lens element, and opening on the rear surface of the first lens element at a point within the area bounded by the annular ridge.
11. An intraocular implant according to claim 10 , wherein the ridge includes one or more circumferential discontinuities or gaps, and the opening of the drain passage is aligned with a gap in the ridge.
12. An intraocular implant according to claim 7 , further comprising a second ridge formed concentrically with the first.
13. An intraocular implant according to claim 12 , wherein the second ridge has one or more gaps.
14. An intraocular implant according to claim 13 , wherein the first ridge includes one or more circumferential discontinuities or gaps, and a gap in the second ridge is radially aligned with a gap in the first ridge.
15. An intraocular implant according to claim 12 , further comprising a drain passage penetrating through the fixed part of the implant and opening on the rear surface of the implant at a point within the area between the two ridges.
16. An intraocular implant according to claim 15 , wherein the drain passage opens on the rear surface of the implant in an area radially aligned with a gap in the first or second ridge.