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1. A contact lens for an eye, the contact lens including an optical zone around an optical centre and covering a surface area, a first region within the optical zone covering a substantial portion of the surface area of the optical zone, a decentred second region within the optical zone and defined about a geometric centre that is decentred relative to the optical centre, wherein the decentred second region covers a different portion of the surface area of the optical zone to the first region and has a surface area of at least 5% of the surface area of the optical zone, and a non-optical peripheral carrier zone about the optical zone; wherein at least the first region is configured with a base prescription providing refractive correction for the eye, and the decentred second region is configured with an astigmatic, or toric, power distribution providing at least in part a regional conoid of Sturm on the retina of the eye; and wherein the non-optical peripheral carrier zone is configured with a thickness profile that is substantially rotationally symmetric about the optical centre to facilitate substantially free rotation of the contact lens over time when on the eye, wherein in one rotational position of the contact lens on the eye, the contact lens provides a first region of the retina of the eye with the refractive correction and not the regional conoid of Sturm, and in another rotational position the contact lens provides the first region of the retina with the regional conoid of Sturm.
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