Ophthalmic lens with progressive addition of power and prism
View Patent ↗The lens presents horizontal prismatic refractive power that varies progressively along the main progression meridian (MM′) with the addition of horizontal prismatic power being greater than 2 prismatic diopters in absolute value, this addition of horizontal prismatic power being defined by the difference between the horizontal prismatic refractive power at the reference point (L) of the far vision zone and the horizontal prismatic refractive power at the projection point (P′) of the reference point (P) of the near vision zone (VP) on the vertical line passing through the reference point (L) of the far vision zone.
1. An ophthalmic lens with progressive addition of spherical power, the lens possessing a far vision zone (VL), a near vision zone (VP), and an intermediate vision zone (VI) situated between the two preceding zones, these three zones being crossed by a main progression meridian (MM′) along which the spherical refractive power (Pu) of the lens varies progressively, said lens having optical corrective power defined in particular by:
spherical power addition (ΔPu) equal to the variation in spherical refractive power between a reference point (L) of the far vision zone and a reference point (P) of the near vision zone (VP), these two points (P, L) being situated on the main progression meridian (MM′);
nominal spherical power (ΔPn) equal to the spherical refractive power at said reference point (L) of the far vision zone (VL); and
nominal astigmatism (An) equal to the cylindrical refractive power at said reference point (L) of the far vision zone (VL) of less than 1 diopter;
the lens presenting horizontal prismatic refractive power (Prh) that varies progressively along the main progression meridian (MM′) with an addition of horizontal prismatic power (ΔPrh) greater than 2 prismatic diopters in absolute value, said addition of horizontal prismatic power (ΔPrh) being defined as the difference between the horizontal prismatic refractive power (Prh(L)) at the reference point (L) of the far vision zone and the horizontal prismatic refractive power (Prh(P′)) at the projection point (P′) of the reference point (P) of the near vision zone (VP) onto the vertical line passing through the reference point (L) of the far vision zone.
2. A lens according to claim 1 , in which the addition of horizontal prismatic power (ΔPrh) is less than 5 prismatic diopters in absolute value.
3. A lens according to claim 2 , in which the addition of horizontal prismatic power (ΔPrh) lies in the range 2.5 to 3.5 prismatic diopters in absolute value.
4. A lens according to claim 1 , in which the horizontal prismatic power (Prh(L)) at the reference point (L) of the far vision zone (VL) is less than 1 prismatic diopter, and preferably less than 0.5 prismatic diopters, in absolute value, in the absence of any prescribed prismatic correction.
5. A lens according to claim 1 , in which the nominal power (Pn) lies in the range +0.75 diopters to −10 diopters.
6. A lens according to claim 1 , in which the function with which horizontal prism (Prh) varies along the meridian is continuous to the second order.
7. The use of a lens according to claim 1 for fabricating visual equipment for subjects with myopia or emmetropia.
8. The use of a lens according to claim 7 for fabricating visual equipment for children with myopia.
9. The use of a lens according to claim 1 for fabricating visual equipment for a subject with presbyopia.
10. A method of correcting and/or visually training a subject with presbyopia, comprising wearing visual equipment comprising at least one ophthalmic lens according to claim 1 .
11. A method according to claim 10 for correcting a subject with presbyopia presenting exophoria or esophoria in near vision, in which the addition of prism by the lens is respectively nasally based or temporally based.
12. A method according to claim 10 for visually training a subject with presbyopia presenting exophoria or esophoria in near vision, in which the addition of prism by the lens is respectively temporally based or nasally based.
13. A method of correcting and/or preventing ametropia, in particular of myopia, comprising wearing visual equipment comprising at least one corrective ophthalmic lens with progressive addition of power possessing a far vision zone (VL), a near vision zone (VP), and an intermediate vision zone (VI) situated between the two preceding zones, these three zones being crossed by a main progression meridian (MM′) along which the spherical power (Pu) and also the horizontal prismatic power (Prh) both vary progressively.
14. A method according to claim 13 , in which said lens is an ophthalmic lens with progressive addition of spherical power, the lens possessing a far vision zone (VL), a near vision zone (VP), and an intermediate vision zone (VI) situated between the two preceding zones, these three zones being crossed by a main progression meridian (MM′) along which the spherical refractive power (Pu) of the lens varies progressively, said lens having optical corrective power defined in particular by:
spherical power addition (ΔPu) equal to the variation in spherical refractive power between a reference point (L) of the far vision zone and a reference point (P) of the near vision zone (VP), these two points (P, L) being situated on the main progression meridian (MM′);
nominal spherical power (Pn) equal to the spherical refractive power at said reference point (L) of the far vision zone (VL); and
nominal astigmatism (An) equal to the cylindrical refractive power at said reference point (L) of the far vision zone (VL) of less than 1 diopter;
the lens presenting horizontal prismatic refractive power (Prh) that varies progressively along the main progression meridian (MM′) with an addition of horizontal prismatic power (ΔPrh) greater than 2 prismatic diopters in absolute value, said addition of horizontal prismatic power (ΔPrh) being defined as the difference between the horizontal prismatic refractive power (Prh(L)) at the reference point (L) of the far vision zone and the horizontal prismatic refractive power (Prh(P′)) at the projection point (P′) of the reference point (P) of the near vision zone (VP) onto the vertical line passing through the reference point (L) of the far vision zone.
15. A method according to claim 13 , applied to children with myopia.
16. A method according to claim 13 , applied to a subject with myopia presenting exophoria in near vision, in which the addition of prism by the lens is nasally based.
17. A method according to claim 13 , applied to a subject with myopia presenting esophoria in near vision, in which the addition of prism by the lens is temporally based.