Ophthalmic lens with multiple phase plates

#1. Field of the Invention

#This invention relates generally to an ophthalmic lens, and more specifically to multifocal ophthalmic lenses that combine both refraction and diffraction to provide an ocular image.

#2. Description of the Related Art

#Embodiments of the present invention may be better understood from the following detailed description when read in conjunction with the accompanying drawings. Such embodiments, which are for illustrative purposes only, depict the novel and non-obvious aspects of the invention. The drawings include the following 19 figures, with like numerals indicating like parts:

#FIG. 1 is a side view of a prior art bifocal intraocular lens illustrating how light from a distant object is focused onto the retina of an eye.

#FIG. 2 is a side view of a prior art bifocal intraocular lens illustrating how light from a near point source object is focused onto the retina of an eye.

#Embodiments of the present inventions are directed to a multifocal ophthalmic lens (e.g., an intraocular lens (IOL), phallic IOL, and corneal implant) comprising a plurality of surface regions having both a refractive optical power and a diffractive optical power that together provide enhanced ocular vision. The terms “power” or “optical power”, as used herein, mean the ability of a lens, an optic, an optic surface, or at least a portion of an optic surface to redirect incident light for the purpose of forming a real or virtual focus or focal point. The optical power may result from reflection, refraction, diffraction, or some combination thereof and is generally expressed in units of Diopters. One of skill in the art will appreciate that the optical power of a surface, lens, or optic is generally equal to the reciprocal of the focal length of the surface, lens, or optic when the focal length is expressed in units of meters. As used herein, the term “refractive optical power” or “refractive power” means optical power produced by the refraction of light as it interacts with a surface, lens, or optic. As used herein, the term “diffractive optical power” or “diffractive power” means optical power resulting from the diffraction of light as it interacts with a surface, lens, or optic, for example as produced by a diffraction order of a phase plate. When used in reference to a phase plate, the term “diffractive optical power” or “diffractive power” means the substantially equivalent optical power attributed to a refractive lens that converges or diverges light at a design wavelength in substantially the same manner as the diffractive phase plate for which the term is used.

#FIG. 1 illustrates a prior art bifocal IOL 20 with an optical axis 21 disposed in an eye 22. The IOL 20 comprises phase plate 23 made, for example, in accordance with the teachings of Freeman in U.S. Pat. No. 4,642,112 or Cohen in U.S. Pat. No. 5,144,483. The phase plate 23 is disposed on an anterior surface 24 having a base curvature C and is illuminated by incident light 26 from a distant object that enters the eye 22 in the form of collimated light. A first portion 27 of the incident light 26 is substantially unaffected by the phase plate 23 and is focused by the anterior surface 24 and a posterior surface 28 through refraction to produce a first focus 29 approximately located on a retina 30 of the eye 22 for providing distant vision. A second portion 32 of the incident light 26 is diffracted by the phase plate 23 to form a second focus 34 for providing near or intermediate vision. The net optical power of the anterior surface 24 for forming the second focus 34 is generally considered to be a combination of (1) a refractive optical power of the anterior surface 24 due to the base curvature C and (2) a diffractive optical power of the phase plate 23. It will be appreciated that in an actual eye, the light forming the second focus 34 would continue propagating towards the retina 30; however, this light is illustrated as terminating at the second focus 34 for purposes of clarity.

#The term “near vision,” as used herein, refers to vision provided by at least a portion of a lens, such as the IOL 20, or an imaging system, wherein objects relatively close to the subject are substantially in focus on the retina of the eye of a subject. The term “near vision” generally corresponds to vision provided when objects are at a distance between about 25 cm to about 50 cm. Conversely, the term “distant vision,” as used herein, refers to vision provided by at least a portion of a lens or imaging system, wherein objects relatively far from the subject are substantially on the retina of the eye. The term “distant vision” generally corresponds to vision provided when objects are at a distance of at least about 1 meter to about 2 meters away from the subject, preferably at a distance of 5 to 6 meters or greater. The term “intermediate vision” generally refers to vision provided by at least a portion of a lens or imaging system, wherein objects at an intermediate distance from the subject are substantially in focus on the retina of the eye. Intermediate vision generally corresponds to vision provided when objects are at a distance of about 40 centimeters to about 1.5 meters.