Intraocular Lens with Fresnel Prism
First Claim
1. An intraocular lens having an optical axis, the lens comprising, as one face thereof, a Fresnel prism comprising an array of elongate prism elements which are parallel to one another along their length, each prism element having an elongate facet which is oriented such that a perpendicular to the facet is at an angle to the optical axis,wherein the array of prism elements is configured to deviate light incident thereon to an off-axis position lying in a plane defined by the optical axis and the perpendicular to any of the angled facets,and wherein one or more of the pitch and the size of prism elements is non-uniform across the array and is selected to reduce a diffraction grating effect associated with the array of prism elements, whereby light incident on the lens is preferentially directed into the zero order diffraction direction and chromatic angular dispersion is reduced.
1 Assignment
0 Petitions
Accused Products
Abstract
An intraocular lens is described which comprises, as one face thereof, a linear Fresnel prism array with facets angled relative to the optical axis of the lens so as to deviate light incident thereon to an off-axis position. The facets are modified so as to reduce at least one of diffraction effects and astigmatism associated with the Fresnel prism. In particular, by varying the pitch of the prism elements across the array, which may comprise varying their size, a diffraction grating effect can be reduced or negated, such that light is not diffracted into undesirable orders and multiple images can be avoided. Furthermore, chromatic angular dispersion associated with the diffraction grating effect may be reduced. The pitch variation can be random. By varying the angle of the facets across the array, astigmatism that would otherwise result from the presence of the Fresnel prism can also be compensated.
28 Citations
24 Claims
-
1. An intraocular lens having an optical axis, the lens comprising, as one face thereof, a Fresnel prism comprising an array of elongate prism elements which are parallel to one another along their length, each prism element having an elongate facet which is oriented such that a perpendicular to the facet is at an angle to the optical axis,
wherein the array of prism elements is configured to deviate light incident thereon to an off-axis position lying in a plane defined by the optical axis and the perpendicular to any of the angled facets, and wherein one or more of the pitch and the size of prism elements is non-uniform across the array and is selected to reduce a diffraction grating effect associated with the array of prism elements, whereby light incident on the lens is preferentially directed into the zero order diffraction direction and chromatic angular dispersion is reduced.
-
9. An intraocular lens having an optical axis, the lens comprising, as one face thereof, a Fresnel prism comprising an array of elongate prism elements which are parallel to one another along their length, each prism element having an elongate facet which is oriented such that a perpendicular to the facet is at an angle to the optical axis,
wherein the array of prism elements is configured to deviate light incident thereon to an off-axis position lying in a plane defined by the optical axis and the perpendicular to any of the angled facets, and wherein the angle of the prism element facets is non-uniform across the array and is selected to compensate for astigmatism that would otherwise result from the presence of the Fresnel prism.
Specification
-
- Resources
-
Current AssigneeRayner Intraocular Lenses Ltd. (Rayner Surgical Group Ltd.)
-
Original AssigneeRayner Intraocular Lenses Ltd. (Rayner Surgical Group Ltd.)
-
InventorsPurchase, Daniel, Toop, Peter
-
Application NumberUS13/511,529Publication NumberTime in Patent OfficeDaysField of SearchUS Class Current623/6.26CPC Class CodesA61F 2/1656 Fresnel lenses, prisms or p...
