Multifocal contact lenses
The invention provides methods for correcting presbyopia and lenses for such correction in which production of a full range of multifocal lenses is accomplished using three rotationally symmetric, aspheric back surfaces, the design of which base curves is a function of refractive power.
1. A method for designing a contact lens, comprising the step of providing an aspheric, rotationally symmetric base curve that is a function of refractive error, wherein the base curve is selected from the group consisting of a first surface having a sphere power of about −12 to about −2 diopters, an apical curvature of about 7.8+/−0.2 mm and an asphericity constant of about −0.25+/−0.02, a second surface having a sphere power of about −2 to about +2 diopters, an apical curvature of about 8.0+/−0.2 mm and an asphericity constant of about −0.17+/−0.02 and a third surface having a sphere power of about +2 to about +12 diopters, an apical curvature of about 8.2+/−0.2 mm and an asphericity constant of about −0.10+/−0.02.
2. The method of claim 1 , further comprising the step of providing a front surface having a central optic zone comprising distance or near vision power and at least two concentric annular zones of power, each of the annular zones comprising distance or near vision power.
3. The method of claim 1 , further comprising the step of providing a front surface having an optical zone that is a progressive power zone.
4. A method for designing a contact lens, comprising the step of providing an aspheric, rotationally symmetric base curve that is a function of refractive error, wherein the base curve is selected from the group consisting of a first surface having a sphere power of about −12 to about 0 diopters, an apical curvature of about 7.8+/−0.2 mm and an asphericity constant of about −0.25+/−0.02 and a second surface having a sphere power of about 0 to about +12 diopters, an apical curvature of about 8.2+/−0.2 mm and an asphericity constant of about −0.10+/−0.02.
5. The method of claim 4 , further comprising the step of providing a front surface having a central optic zone comprising distance or near vision power and at least two concentric annular zones of power, each of the annular zones comprising distance or near vision power.
6. The method of claim 4 , further comprising the step of providing a front surface having an optical zone that is a progressive power zone.
7. A contact lens, comprising: a.) a first surface having a first optic zone comprising a multifocal region; and b.) a second surface that is an aspheric, rotationally symmetric base curve that is a function of refractive error, wherein the base curve is selected from the group consisting of a first surface having a sphere power of about −12 to about −2 diopters, an apical curvature of about 7.8+/−0.2 mm and an asphericity constant of about −0.25+/−0.02, a second surface having a sphere power of about −2 to about +2 diopters, an apical curvature of about 8.0+/−0.2 mm and an asphericity constant of about −0.17+/−0.02 and a third surface having a sphere power of about +2 to about +12 diopters, an apical curvature of about 8.2 +/−0.2 mm and an asphericity constant of about −0.10+/−0.02.
8. The lens of claim 7 , wherein the first surface comprises a central optic zone comprising distance or near vision power and at least two concentric annular zones of power, each of the annular zones comprising distance or near vision power.
9. The lens of claim 7 , wherein the first surface comprises an optical zone that is a progressive power zone.
10. A contact lens, comprising: a.) a first surface having a first optic zone comprising a multifocal region; and b.) a second surface that is an aspheric, rotationally symmetric base curve that is a function of refractive error, wherein the base curve is selected from the group consisting of a first surface having a sphere power of about −12 to about 0 diopters, an apical curvature of about 7.8+/−0.2 mm and an asphericity constant of about −0.25+/−0.02 and a second surface having a sphere power of about 0 to about +12 diopters, an apical curvature of about 8.2+/−0.2 mm and an asphericity constant of about −0.10+/−0.02.
11. The lens of claim 10 , wherein the first surface comprises a central optic zone comprising distance or near vision power and at least two concentric annular zones of power, each of the annular zones comprising distance or near vision power.
12. The lens of claim 10 , wherein the first surface comprises an optical zone that is a progressive power zone.