Patent ID: 6923540

Claim:
A toric multifocal contact lens comprising a central axis, an anterior surface having a first central optical zone, and an opposite posterior surface having a second central optical zone, wherein one of the first central optical zone and the second central optical zone has a central circular area and an annular region surrrounding the central circular area, wherein the central circular area has a diameter of about 1.0 to about 3.0 mm and is a progressive power addition zone for near vision correction and optionally for intermediate vision correction, wherein the annular region has a spherical or aspheric surface having an optical power for distant vision correction, wherein the central circular area and the annular region are concentric with the central axis, wherein the other one of the first central optical zone and the second central optical zone is a toroidal surface or a biconic surface, wherein the progressive power addition zone has a surface that provides a power addition profile defined by two or more linear functions of equation (3) or by equation (4) or equation (5) { p ⁡ ( x ) = b 1 + k 1 ⁢ x 0 ≤ x < x 1 p ⁡ ( x ) = b 2 + k 2 ⁢ x x 1 ≤ x < x 2 ⋮ p ⁡ ( x ) = b i + k i ⁢ x x i - 1 ≤ x < x i ⋮ ( 3 ) p ⁡ ( x ) = A 2 · cos ( x D 2 · π ) + A 2 ( 4 ) p ⁡ ( x ) = A · [ 1 - ( x D 2 ) n ] ( 5 ) wherein p(x) is an added power at a distance of x from the center; b i is a coefficient which is the intercept of a linear line; and k i is the rate of change of the added power as function of the distance from the center; A is the maximum added power; D is the diameter of the progressive power addition zone; and n is any number which can be an integer or non-integer larger than 1 but smaller than or equal to 10, and wherein the first and second central optical zone combine to provide a cylindrical optical power to correct astigmatism vision errors and a multifocal optical power to compensate for presbyopia.