Assembly consisting of a pair of multifocal ocular implants

Abstract

An assembly comprising a pair of multifocal ocular implants, wherein each implant has a TFMTF curve, for a pupil of diameter less than or equal to 4 mm, preferably less than 3 mm, having a peak corresponding to the distance vision of the wearer, as well as an asymmetrical peak which spreads between intermediate vision and near vision without discontinuity; for a first implant, the TFMTF value is greater in intermediate vision than that of near vision; for the second implant, the TFMTF value is greater in near vision than that of intermediate vision; the rising edge of the asymmetrical peak of the first implant has, as an absolute value, a mean slope greater than that of its falling edge, whereas the rising edge of the asymmetrical peak of the second implant has, as an absolute value, a mean slope less than that of its falling edge.

Claims

1. An assembly comprising a pair of multifocal ocular implants intended to be worn at the same time by the same person, wherein: each implant of this pair of multifocal ocular implants has a TFMTF (Modulation Transfer Function Through Focus) curve, for a pupil of diameter less than or equal to 4 mm and at a wavelength of 546 nm, which has a peak corresponding to distance vision, and an asymmetrical peak, which spreads between intermediate vision and near vision, without discontinuity between intermediate vision and near vision; for a first implant of this pair of multifocal ocular implants, the TFMTF value of said TFMTF curve is greater in intermediate vision than the TFMTF value of near vision; for a second implant of this pair of multifocal ocular implants, the TFMTF value of said TFMTF curve is greater in near vision than the TFMTF value that of intermediate vision; the rising edge of the asymmetrical peak of the first implant has, as an absolute value, a mean slope greater than that of the falling edge of said asymmetrical peak, whereas the rising edge of the asymmetrical peak of the second implant has, as an absolute value, a mean slope less than that of the falling edge of said asymmetrical peak.

2. The assembly according to claim 1, wherein the overlap of said asymmetrical peaks corresponds to a TFMTF value of at least 0.10.

3. The assembly according to claim 2, wherein the overlap of said asymmetrical peaks corresponds to a TFMTF value of at least 0.15.

4. The assembly according to claim 3, wherein the apex of each asymmetrical peak has a TFMTF value at least equal to 0.15.

5. The assembly according to claim 1, wherein the respective TFMTF values at the apices of the peaks corresponding to distance vision have a difference of less than 30%.

6. An assembly according to claim 1, wherein the TFMTF curve is considered for a pupil of diameter less than or equal to 3 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will become apparent on reading the following description of a preferred embodiment of the invention. This description is given with reference to the appended drawings wherein:

(2) FIGS. 1 to 3, as specified above, illustrate the state of the art in the field of the invention;

(3) FIG. 4 is a representation, on one and the same diagram of the TFMTF curves of two implants forming an assembly according to the invention, for a pupil of 3 mm in diameter and a wavelength of 546 nm (on the abscissa: addition expressed in Diopters/on the ordinate: TFMTF at 50 cycles/mm);

(4) FIG. 5 is an identical view to the preceding one to which is also added the estimate of the TFMTF in binocular vision;

(5) FIG. 6 is a TFMTF curve in binocular vision of implants of the prior art.

DETAILED DESCRIPTION OF THE INVENTION

(6) As has been specified above, the present invention results from the fact that the advantage of having the combination of two so-called “complementary” TFMTF is to make it possible to better merge the vision of both eyes of the wearer of the implants, while permitting a greater difference between the two apices of the VI (intermediate vision) and VP (near vision) peaks than with the prior devices mentioned above which apply the “Mix and Match” principle.

(7) The reader is referred to the appended FIGS. 4 and 5 for a description of the preferred TFMTF curves of the two implants forming the assembly according to the invention.

(8) In these figures, the respective TFMTF curves of each of the two implants are referenced A and B and correspond for example to the dominant eye and the non-dominant eye of the wearer respectively (or conversely).

(9) It should first of all be noted that each A and B curve has a peak, A/VL and B/VL respectively, corresponding to the distance vision of the wearer (with correction of the refractive errors if necessary.)

(10) These peaks are similar for both implants. Under all circumstances, the respective TFMTF values at the apices of the peaks A/VL and B/VL have a difference of less than 20% and preferably less than 10%.

(11) Moreover, the two curves A and B have an “asymmetrical widened peak”, A/PE and B/PE respectively (with respect to a conventional multifocal) which spreads between intermediate vision VI and near vision VP. In other words, there is no distinction of two distinct peaks, but on the contrary, there is continuity of the TFMTF between VI and VP while preserving a minimum level of 0.10, preferably 0.15.

(12) In addition, for a first implant of the assembly corresponding to curve A, the TFMTF value is greater in intermediate vision VI than that of near vision VP.

(13) And conversely, for the second implant of the assembly corresponding to curve B, the TFMTF value is greater in near vision VP than that of intermediate vision VI.

(14) Finally, the two curves complement one another in such a way that they have an asymmetrical profile with an “overall slope” that is gentler in their area of overlap.

(15) In other words, the rising edge FA of the asymmetrical peak A/PE of the first implant has, as an absolute value, a mean slope greater than that of its falling edge FD, whereas the rising edge FA of the asymmetrical peak B/PE of the second implant has, as an absolute value, a mean slope less than that of its falling edge FD.

(16) Advantageously, the TFMTF two curves A and B overlap at a threshold greater than or equal to 0.15.

(17) Thus, in binocular vision, the wearer of the pair of implants of the assembly according to the invention has a TFMTF greater than 0.15 over a much more extended range of distance or depth of field (EDOF), typically of 1D to 2.5D (which corresponds to a distance of vision of 40 cm to 1 m).

(18) Comparatively, “Mix and Match” (M&M) systems of the state of the art offer a clear vision of 40 cm to 66 cm—or even 75 cm—in M&M+2.5D/+3D and M&M+2.25D/+3D respectively.

(19) In addition, the combination of two so-called “complementary” TFMTF also provides a more advantageous binocular vision than that of a trifocal implant having a peak of distance vision VL, a peak of intermediate vision VI, and a peak of near vision VP, with cancellations of the TFMTF between each of these peaks, which translates into an absence of continuous vision between near vision VP and intermediate vision VI. This is illustrated in FIG. 6 where the area of cancellation of the TFMTF is marked by a circle.

(20) The depth of field PC of the binocular TFMTF allows a continuity between its near and intermediate vision without any drop in sharpness between the two, as appears on the curve in broken lines in FIG. 5.

(21) In a well-known manner, one of the main drawbacks associated with multifocal implants is the presence of halos.

(22) Thus, with a bifocal implant, in night vision, and mainly when driving (that is to say when the “useful” vision is distance vision), the wearer can be bothered by the halo created by the near vision VP peak.

(23) On the other hand, with a trifocal implant, the distance vision is associated with two halos corresponding to the near vision and intermediate vision peaks. However, since the height of these two peaks is smaller, the effect of these halos is less bothersome for the wearer than with a conventional bifocal implant.

(24) In other words, the wearer better tolerates several weaker halos rather than a strong and well-defined halo.

(25) Thus, the use of two “complementary” implants according to the invention makes it possible to create a continuous or diffuse halo which is less bothersome in conditions of distance vision and especially of night driving.

(26) Those skilled in the art will proceed with the fabrication of two intraocular implants (implants of the crystalline lens capsule, of the anterior chamber or intracorneal) with different multifocal optical surfaces (refractive or preferably diffractive), so that these have the features expressed above.

(27) As for implants of the prior art, these implants can be put in place on the eyes of a patient using an injector. And when this placement is performed in the crystalline lens capsule, they are introduced in the folded position through a slit of small dimensions provided for this purpose.

(28) Although the present description has been made in relation to intraocular implants, the present invention also applies to intracorneal implants and to “piggybacks”, i.e. implants placed in front of the crystalline lens capsule.