Intermediate vision with phakic multifocal optics utilizing residual accommodations
View Patent ↗In one aspect, the present invention provides a method of correcting vision, which comprises determining a residual accommodation exhibited by a natural, crystalline lens of an eye, and selecting a multifocal intraocular lens (IOL), which exhibits a far-focus optical power (e.g., in a range of about −15 to about +50 Diopters (D)) and an add power (e.g., in a range of about 1 D to about 4 D), for implantation in the eye while retaining the natural lens. The add power of the IOL is selected as a function of the residual accommodation such that a combination of the IOL and the natural lens provides a visual contrast greater than about 10% at a spatial frequency of about 20 cycles/degree for viewing objects at a distance greater than about 30 cm from the eye.
1. A multifocal, phakic intraocular lens (IOL) suitable for implantation in an eye while retaining the natural crystalline lens, comprising:
an optic providing a far focus and a near focus characterized by an optical power and an add power, the add power being in a range of about 1 D to about 4.5 D, wherein a depth-of-focus associated with at least one of the far or near focus is greater than about 1 D,
wherein the optic further comprises an anterior and a posterior optical surface configured to provide the far focus, and a diffractive structure disposed on one of the surfaces providing the add power,
wherein the add power of the IOL is selected as a function of a residual accommodation exhibited by the natural crystalline lens, such that a combination of the IOL and the natural crystalline lens provides a visual contrast greater than about 10% at a spatial frequency of about 20 cycles/degree for viewing objects at a distance greater than about 30 cm from the eye,
wherein the visual contrast is characterized by a through-focus modulation transfer function (MTF) at a selected radiation wavelength and for a given aperture size, and,
wherein the depth-of-focus associated with the far or near focus is selected such that a shift of the far or near focus of the eye caused by the residual accommodation of the natural crystalline lens results in an intermediate or a near vision, respectively, with a visual contrast greater than about 10% at a spatial frequency of about 20 cycles/degree.
2. The IOL of claim 1 , wherein the depth-of-focus is in a range of about 1 D to about 4.5 D.
3. The IOL of claim 1 , wherein the depth-of-focus is in a range of about 1 D to about 2.5 D for an add power in a range of about 1 to about 2.5 D.
4. The IOL of claim 1 , wherein the depth-of-focus is in a range of about 2.5 D to about 4.5 D for an add power in a range of about 2.5 D to about 4.5 D.
5. The IOL of claim 1 , wherein the optic provides a far-focusing power in a range of about −15 D to about +50 D Diopters.