Ophthalmic lens shaping

Abstract

The present application relates to ophthalmic lens shaping. Apparatus and methods are described that include an add-on lens (24) made of a non-crystalline viscoelastic material and having an optical design. The curvature of the add-on lens (24) is changed to conform to the curvature of a base lens (22) without causing a loss of the optical design of the add-on lens (24) by heating the add-on lens (24) to a temperature at which the tangent of the loss angle of the non-crystalline viscoelastic material is between 0.2 and 0.8, and shaping the add-on lens (24). Subsequently, the add-on lens (24) is adhered to the base lens (22). The optical design of the add-on lens (24) is such that upon adhesion to the base lens (22), the adhered base lens (22) and add-on lens (24) provide a combined lens (20) having a desired optical prescription. Other applications are also described.

Description

[0001] This application is a divisional application of application number 202180019255.0, filed on March 16, 2021, having the title “Shaping an ophthalmic lens”.

[0002] Cross Reference to Related Applications

[0003] This application claims priority to the following applications:

[0004] U.S. Provisional Patent Application No. 63 / 002,388, filed on March 31, 2020, by Halahmi et al., entitled “Shaping an ophthalmic lens”, and

[0005] U.S. Provisional Patent Application No. 63 / 002,393, filed on March 31, 2020, by Halahmi et al., entitled “Stress-release procedure for an ophthalmic lens”.

[0006] Both of the above-cited U.S. Provisional Applications are incorporated herein by reference. TECHNICAL FIELD

[0007] Some applications of the present invention relate generally to ophthalmic lenses. In particular, some applications relate to shaping ophthalmic lenses. BACKGROUND

[0008] Ophthalmic lenses are typically made of amorphous viscoelastic polymers, which exhibit both elastic and plastic properties. In a theoretical material with purely elastic properties, the strain manifests itself immediately as a response to the stress. In a theoretical material with purely plastic properties, the strain caused by the stress manifests itself with a delay (from milliseconds to years) with respect to the stress applied to the material. Phenomena related to plasticity are creep (where the strain continuously changes as long as a stress is applied to the plastic material) and relaxation (where the stress decreases as long as the plastic material remains in a predetermined size and has an internal pre-loaded stress).

[0009] When a theoretical purely plastic material is loaded with a sinusoidally varying stress, the resulting strain is detected, but with a delay, which can be characterized as a phase shift. Materials in the real world are typically viscoelastic, exhibiting both plastic and elastic properties. Viscoelastic materials exhibit a phase shift, but a smaller one than the theoretical purely plastic material. Figure 1 This is illustrated by the following figure, Figure 1A sinusoidal stress-time curve and the resulting sinusoidal strain-time curve are shown, the strain-time curve being phase shifted with respect to the stress-time curve.

[0010] The response of a viscoelastic material to the application of mechanical energy to the material can be characterized by its storage modulus (E') and its loss modulus (E"), both of which are temperature dependent. The storage modulus of a material is a measure of its elastic behavior, i.e., the degree to which mechanical energy applied to the material is stored in the stretching of bonds along the polymer chains (for release during recovery). The loss modulus is a measure of the material's plastic behavior, i.e., the degree to which mechanical energy applied to the material is lost due to internal friction between the polymer chains (this energy is not stored and subsequently released). Another parameter, which is also temperature dependent and is referred to as the material's tan delta (Tan Delta), measures the ratio of the loss modulus to the storage modulus at any temperature. Thus, the tan delta of a material is a measure of the material's tendency to dissipate and dimensional instability. As noted, generally, all three of the above parameters (i.e., storage modulus, loss modulus, and tan delta) vary as a function of the temperature of the material. These parameters are determined by analyzing the material using dynamic mechanical analysis (also referred to as "DMA analysis").

[0011] Presbyopia is a disease that gradually affects most people over the age of 40. This disease causes the ability to clearly focus on near objects to gradually deteriorate. Presbyopia is usually treated with multifocal glasses, progressive glasses or contact lenses, as laser-assisted keratomileusis (i.e., LASIK) and other types of surgery are not suitable for treating this disease.

[0012] Corrective lenses are used in eyeglasses to correct presbyopia and other accommodation disorders. Many people with presbyopia also have myopia (i.e., nearsightedness). The basic solution for these people is to use multifocal eyeglass lenses. Multifocal eyeglass lenses contain two or more lens powers, where each power is suitable for objects at a respective distance. Bifocal eyeglasses contain two lens powers; trifocal eyeglasses contain three lens powers. Progressive eyeglass lenses are characterized by a gradient of increasing lens power. The gradient starts with the wearer's distance prescription and reaches a maximum add power or full reading add value at the lower part of the lens. The add value in the middle of the lens usually enables clear vision in the intermediate range, for example, to read text on a computer screen. The length of the progressive power gradient on the lens surface depends on the lens design, with the final add power typically being between 0.50 diopters and 3.50 diopters. The prescribed add value depends on the degree of presbyopia of the patient. SUMMARY

[0013] According to some applications of the present application, the one or more lenses are made of a base lens and an additional lens adhered to the base lens. For some applications, the additional lens is a progressive lens and the base lens is a single vision corrective lens (e.g., a distance vision corrective lens), wherein the optical design of the additional lens is such that, when adhered to the base lens, the combined lens becomes a progressive lens matching the desired prescription.

[0014] As mentioned in the background section above, the response of a viscoelastic material to the application of mechanical energy to the material can be characterized by its storage modulus (E’) and its loss modulus (E”). The storage modulus of a material is a measure of its elastic behavior, i.e., the extent to which mechanical energy applied to the material is stored (to be released during recovery) in the stretching of bonds along the polymer chains. The loss modulus is a measure of the material’s plastic behavior, i.e., the extent to which mechanical energy applied to the material is lost due to internal friction between the polymer chains (these energies are not stored and subsequently released). Another parameter, known as the loss tangent of the material, measures the ratio of the loss modulus to the storage modulus. Thus, the loss tangent of a material is a measure of the material’s tendency to dissipate and dimensional instability. Typically, all three of the above-mentioned parameters (i.e., the storage modulus, the loss modulus, and the loss tangent) vary as a function of the temperature of the material. These parameters are determined by analyzing the material using dynamic mechanical analysis (also referred to as “DMA analysis”).

[0015] Typically, the additional lens is made of an amorphous viscoelastic polymer and, depending on the need as described above, is initially formed to exhibit a given lens optical design (e.g., when adhered to a base lens, the combination of the base lens and the additional lens forms a progressive lens). For example, the additional lens can be initially formed using a forming process such as injection molding, injection compression molding, compression molding, stamping, 3D printing, and / or casting. In order to adhere the additional lens to the base lens, it is typically desirable for the additional lens to undergo a further shaping process to conform the curvature of the additional lens to the curvature of the base lens. In particular, the surface of the additional lens that is adhered to the base lens needs to be shaped to substantially conform to the surface of the base lens to which it is adhered. It should be noted that in some cases, the curvature of the additional lens is made slightly larger than the curvature of the base lens to facilitate the adhesion process described herein. Furthermore, it should be noted that in some cases, and particularly if the curvature of the additional lens and the curvature of the base lens are similar to each other, it is not necessary to shape the additional lens prior to the adhesion step. However, the inventors have found that a significant portion of the combination of the additional lens and the base lens typically requires the shaping technique as described herein to be applied to the additional lens permanently. This is particularly true when the ophthalmic prescription includes a cylinder with an associated cylinder axis value, the cylinder tending to have an impact on the concave curvature of the base lens.

[0016] Note that the alternative of reshaping the add-on lens so that its curvature conforms to that of the base lens is to initially shape the add-on lens so that it has the desired optical design and is also shaped to conform to the shape of the base lens. However, this would greatly increase the number of add-on lenses that a retailer or optical laboratory would need to stock, as it would be necessary to stock separate inventory units of add-on lenses having a given optical design but with different curvatures in order to conform to the respective differently shaped base lenses. (This is especially true when the ophthalmic prescription includes a cylinder with an associated cylinder axis value, as the cylinder tends to have an impact on the concave curvature of the base lens, as noted above.) Alternatively, this would mean that the add-on lens would have to be manufactured in a custom manner (based on the optical requirements of the patient and the selection of the base lens), in which case the many advantages of using the base lens and add-on lens rather than using conventional manufacturing techniques to manufacture progressive lenses would be lost.

[0017] As the predetermined sub-regions of the lens are very precise (at the level of thickness differences in microns), the shaping of the lens is very challenging. Shaping the progressive lens in an uncontrolled manner risks destroying the optical values of the lens. It is desirable that, after the add-on lens is shaped in the manner described above, the add-on lens not only maintains its optical design at the predetermined, clinically important sub-regions within the ISO standard after being reshaped and adhered to the base lens, but also maintains approximately the same residual cylinder quantities at the predetermined, clinically important sub-regions of the lens. Furthermore, in general, it is desirable to achieve that the lens retains its original optical design within the tolerances at the predetermined sub-regions of the lens, while the ophthalmic lens does not retain significant internal stresses (of the type that can cause the add-on lens to crack, or to experience stress cracking during the lifetime of the add-on lens). For some applications, the curvature of the add-on lens can change by more than plus / minus 1 diopter (e.g., more than plus / minus 2 diopters), and / or by up to plus / minus 4 diopters (e.g., up to plus / minus 3 diopters) while retaining the lens optical design and not introducing significant stresses to the lens, by applying the lens shaping process described herein, as noted above.

[0018] The inventors of the present application have discovered that if the add-on lens is shaped at a temperature where the tangent of the loss angle is greater than 0.8 (or in some cases greater than 0.5 or 0.3), this often causes irreversible damage to the lens optical design. This is because when the lens is shaped under stress at such temperatures, the deformation of the lens often induces plastic deformation, such that when the lens returns to ambient temperature, the components of the optical design with the lens are lost, and unwanted cylindrical power can appear. On the other hand, the inventors have discovered that if the add-on lens is shaped at a temperature where the tangent of the loss angle is less than 0.2 (and in some cases less than 0.5 or less than 0.3), this allows the add-on lens to retain its lens optical design, but leaves internal stresses in the lens that can later develop into cracks or regions of the lens that lose transparency due to the stresses. For example, the lens can form cracks due to the internal stresses in combination with thermal cycling, thermal shock, mechanical shock, or environmental stresses (e.g., due to fluids secreted by the body and / or chemical cleaning materials). The slow crack growth phenomenon of polymers (particularly amorphous polymers) is well known, and is further accelerated by the fact that fats (e.g., human fat or oil, from the hands or face), oils, cleaners, and soaps can come into contact with the add-on lens over the life of the add-on lens. An additional risk associated with shaping the add-on lens at a temperature where the tangent of the loss angle is less than 0.2 (and in some cases less than 0.5 or less than 0.3) is that the add-on lens will tend to revert to its original shape, which will cause the add-on lens to separate from the base lens.

[0019] According to some applications of the present application, therefore, the add-on lens is shaped at a temperature where the tangent of the loss angle of the material from which the add-on lens is made is greater than 0.2 and / or less than 0.8. For some applications, the add-on lens is shaped at a temperature where the tangent of the loss angle of the material from which the add-on lens is made is 0.2-0.5 or 0.2-0.3. Alternatively or additionally, the add-on lens is shaped at a temperature where the tangent of the loss angle of the material from which the add-on lens is made is 0.3-0.8 or 0.5-0.8. Furthermore, typically, the temperature at which the add-on lens is shaped is at least 5 degrees Celsius (e.g., at least 10 degrees Celsius) below the peak of the tangent of the loss angle / temperature curve. Typically, within the above-mentioned tangent of the loss angle ranges, the material retains its original lens optical design while only retaining low residual stresses.

[0020] According to some applications of the present application, therefore, a method for use with a base lens is provided, the method comprising:

[0021] forming the add-on lens from an amorphous viscoelastic material such that the add-on lens has an optical design;

[0022] changing the curvature of the add-on lens such that the curvature of the add-on lens conforms to the curvature of the base lens without causing a loss of the optical design of the add-on lens by:

[0023] heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8; and

[0024] shaping the additional lens so that the curvature of the additional lens conforms to the curvature of the base lens while the additional lens is at the temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8; and

[0025] subsequently adhering the additional lens to the base lens, the optical design of the additional lens being such that, upon adherence to the base lens, the adhered base lens and additional lens provide a combination lens having a desired optical prescription.

[0026] In some applications, heating the additional lens includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8, and to a temperature that is less than a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is at its peak.

[0027] In some applications, heating the additional lens includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8, and to a temperature that is at least 5 degrees Celsius less than a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is at its peak.

[0028] In some applications, forming the additional lens from an amorphous viscoelastic material includes forming the additional lens from an amorphous thermoplastic material.

[0029] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8 includes facilitating shaping of the additional lens without the additional lens retaining significant internal stress.

[0030] In some applications, the base lens includes a single-vision optical corrective lens, and adhering the additional lens to the base lens includes forming a combination progressive lens that provides a desired optical prescription.

[0031] In some applications, shaping the additional lens includes shaping the additional lens over a time period of 0.1 seconds to 1 hour while the additional lens is at the temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8.

[0032] In some applications, forming the additional lens from an amorphous viscoelastic material to have an optical design includes using a forming process to form the additional lens from the amorphous viscoelastic material, the forming process being selected from the group consisting of: injection molding, injection compression molding, compression molding, stamping, 3D printing, casting, and any combination thereof.

[0033] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8 includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.3 and 0.8.

[0034] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.3 and 0.8 includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.5 and 0.8.

[0035] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8 includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.5.

[0036] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.5 includes heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.3.

[0037] In some applications, the additional lens is coated with a functional coating, and changing the curvature of the additional lens so that the curvature of the additional lens conforms to the curvature of the base lens includes changing the curvature of the functional coating without causing a loss of functionality of the functional coating.

[0038] In some applications, changing the curvature of the functional coating without causing a loss of functionality of the functional coating includes changing the curvature of the functional coating without introducing significant stress to the additional lens.

[0039] In some applications, changing the curvature of the functional coating without causing a loss of functionality of the functional coating includes changing the curvature of the functional coating without introducing significant stress to the functional coating.

[0040] In some applications, heating the additional lens to a temperature at which the tangent of the loss angle of the amorphous viscoelastic material is between 0.2 and 0.8 includes heating the additional lens to a temperature at which the tangent of the loss angle of a material from which the functional coating is made is between 0.2 and 0.8.

[0041] In some applications, the additional lens is coated with a hard coating, and changing the curvature of the functional coating without causing a loss of functionality of the functional coating includes changing the curvature of the hard coating without introducing significant stress to the hard coating.

[0042] In some applications, the additional lens is coated with a hard coating, and changing the curvature of the functional coating without causing a loss of functionality of the functional coating includes changing the curvature of the hard coating without introducing significant stress to the additional lens.

[0043] In some applications, the additional lens is coated with a hard coating, and changing the curvature of the functional coating without causing a loss of functionality of the functional coating includes changing the curvature of the hard coating without causing the hard coating to crack.

[0044] In some applications, the additional lens is coated with a functional coating selected from the group consisting of: a hard coating, an anti-reflective coating, a super-hydrophobic coating, an anti-static coating, a cleaning coating, a blue light filter, a reflective coating, a UV-resistant coating, a photochromic coating, a polarizing coating, and any combination thereof.

[0045] In some applications, shaping the additional lens includes applying a pressure of 0.01-100 kg per square centimeter to the additional lens while the additional lens is at the temperature at which the loss tangent of the amorphous viscoelastic material is between 0.2 and 0.8.

[0046] In some applications, shaping the additional lens includes applying a pressure of 0.2-1 kg per square centimeter to the additional lens while the additional lens is at the temperature at which the loss tangent of the amorphous viscoelastic material is between 0.2 and 0.8.

[0047] In some applications, shaping the additional lens so that the curvature of the additional lens conforms to the curvature of the base lens includes changing the curvature of the additional lens by more than plus / minus 2 diopters.

[0048] In some applications, shaping the additional lens so that the curvature of the additional lens conforms to the curvature of the base lens includes changing the curvature of the additional lens by up to plus / minus 4 diopters.

[0049] In some applications, the method further includes, after adhering the additional lens to the base lens, applying a heat treatment to the additional lens to release stress from the additional lens.

[0050] In some applications, the method further includes, after adhering the additional lens to the base lens, applying a pressure treatment to the combined lens to remove any voids that can be located between the additional lens and the base lens.

[0051] In some applications, the method further includes, after adhering the additional lens to the base lens, applying a pressure treatment to the combined lens to remove any air bubbles that can be disposed between the additional lens and the base lens.

[0052] In some applications, shaping the additional lens includes pressing the additional lens into a mold using a pressure-applying surface made of a relatively soft material while the additional lens is at the temperature at which the loss tangent of the amorphous viscoelastic material is between 0.2 and 0.8.

[0053] In some applications, shaping the additional lens when the loss tangent of the non-crystalline viscoelastic material is between 0.2 and 0.8 at said temperature comprises directly heating the additional lens via the pressure application surface.

[0054] In some applications, the pressure application surface comprises a pad, and directly heating the additional lens via the pressure application surface comprises directly heating the additional lens using a heating fluid disposed within the pad.

[0055] In some applications, directly heating the additional lens via the pressure application surface comprises directly heating the additional lens via a spiral heating element coupled to the pressure application surface.

[0056] In some applications, the gap between adjacent windings of the spiral heating element decreases from the center of the spiral to the outside of the spiral.

[0057] In some applications, the pressure application surface is made of a material having a hardness less than 90 Shore A.

[0058] In some applications, the pressure application surface is made of a material having a hardness between 20 Shore A and 85 Shore A.

[0059] According to some applications of the invention, there is also provided a method comprising:

[0060] adhering the first lens to the second lens to form a combined lens having a given optical design, the adhering comprising:

[0061] placing the first lens and the second lens in respective first and second pressure chambers, wherein an adhesive layer is disposed between the first lens and the second lens, the pressure within each of the first and second pressure chambers being independently controllable;

[0062] bringing the convex surface of the first lens into contact with the adhesive layer such that a central region of the convex surface of the first lens contacts the adhesive layer first, and the contact between the convex surface of the first lens and the adhesive layer subsequently radiates outwardly from the central region of the convex surface of the first lens until the convex surface of the first lens is covered by the adhesive layer; and

[0063] bringing the concave surface of the second lens into contact with the adhesive layer such that a central region of the concave surface of the second lens contacts the adhesive layer first, and the contact between the concave surface of the second lens and the adhesive layer subsequently radiates outwardly from the central region of the concave surface of the second lens until the concave surface of the second lens is covered by the adhesive layer.

[0064] In some applications, the adhering further comprises, when bringing the convex surface of the first lens into contact with the adhesive layer, reducing the pressure within the first pressure chamber to below ambient pressure.

[0065] In some applications, the adhering further comprises reducing the pressure within the second pressure chamber below ambient pressure when the concave surface of the second lens is brought into contact with the adhesive layer.

[0066] In some applications, bringing the convex surface of the first lens into contact with the adhesive layer such that a central region of the convex surface of the first lens contacts the adhesive layer first comprises forming a convex curve of the adhesive layer facing the convex surface of the first lens by applying a pressure differential between the first pressure chamber and the second pressure chamber.

[0067] In some applications, bringing the concave surface of the second lens into contact with the adhesive layer such that a central region of the concave surface of the second lens contacts the adhesive layer first comprises moving the first lens and the adhesive layer and the second lens towards each other after the convex surface of the first lens is covered by the adhesive layer such that a central region of the convex surface of the first lens on which the adhesive layer is disposed contacts a central region of the concave surface of the second lens and the curvature of the convex surface of the first lens is greater than the curvature of the concave surface of the second lens.

[0068] In some applications, the method further comprises removing any air bubbles trapped between the first lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, autoclaving, and any combination thereof.

[0069] In some applications, the method further comprises removing any air bubbles trapped between the second lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, autoclaving, and any combination thereof.

[0070] In some applications, the method further comprises removing any void volume located between the first lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, and any combination thereof.

[0071] In some applications, the method further comprises removing any void volume located between the second lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, and any combination thereof.

[0072] In some applications, the thickness of the adhesive layer is between 20 microns and 300 microns.

[0073] In some applications, the thickness of the adhesive layer is between 50 microns and 200 microns.

[0074] In some applications, the method further comprises heating at least one element selected from the group consisting of: the second lens, the first lens, the adhesive layer, the first pressure chamber, the second pressure chamber, and any combination thereof during one or more stages of the adhering.

[0075] In some applications, heating the at least one element comprises heating the at least one element to a temperature between 25 degrees Celsius and 75 degrees Celsius.

[0076] In some applications, heating the at least one element comprises heating the at least one element for a time period between 0.1 seconds and 1 hour.

[0077] According to some applications of the invention, there is also provided an apparatus for adhering a first lens having at least one convex surface to a second lens having at least one concave surface to form a combined lens having a given optical design, the apparatus comprising:

[0078] a first pressure chamber configured to accommodate the first lens and a second pressure chamber configured to accommodate the second lens, the pressure within each of the first and second pressure chambers being independently controllable;

[0079] a layer of adhesive disposed between the first and second pressure chambers;

[0080] one or more mechanical pushing elements; and

[0081] a computer processor configured to:

[0082] drive one of the mechanical pushing elements to bring the convex surface of the first lens into contact with the layer of adhesive such that a central region of the convex surface of the first lens is brought into contact with the layer of adhesive first and the contact between the convex surface of the first lens and the layer of adhesive is subsequently radiated outwardly from the central region of the convex surface of the first lens until the convex surface of the first lens is covered by the layer of adhesive; and

[0083] drive one of the mechanical pushing elements to bring the concave surface of the second lens into contact with the layer of adhesive such that a central region of the concave surface of the second lens is brought into contact with the layer of adhesive first and the contact between the concave surface of the second lens and the layer of adhesive is subsequently radiated outwardly from the central region of the concave surface of the second lens until the concave surface of the second lens is covered by the layer of adhesive.

[0084] In some applications, the computer processor is configured to decrease the pressure within the first pressure chamber below ambient pressure when driving one of the mechanical pushing elements to bring the convex surface of the first lens into contact with the layer of adhesive.

[0085] In some applications, the computer processor is configured to decrease the pressure within the second pressure chamber below ambient pressure when driving one of the mechanical pushing elements to bring the concave surface of the second lens into contact with the layer of adhesive.

[0086] In some applications, the computer processor is configured to form a convex curve of the convex face of the first lens facing the adhesive layer by applying a pressure difference between the first pressure chamber and the second pressure chamber.

[0087] In some applications, the device is used with a first lens and a second lens, the first lens and the second lens are shaped such that the curvature of the convex face of the first lens is greater than the curvature of the concave face of the second lens, and the computer processor is configured to, after the convex face of the first lens is covered by the adhesive layer, move the first lens and the adhesive layer and the second lens towards each other such that a central region of the convex face of the first lens on which the adhesive layer is disposed is in contact with a central region of the concave face of the second lens.

[0088] In some applications, the computer processor is configured to remove any air bubbles trapped between the first lens and the adhesive layer and any void volume disposed between the first lens and the adhesive layer by applying air pressure within the first pressure chamber.

[0089] In some applications, the computer processor is configured to remove any air bubbles trapped between the second lens and the adhesive layer and any void volume disposed between the second lens and the adhesive layer by applying air pressure within the second pressure chamber.

[0090] In some applications, the one or more mechanical pushing elements are configured to remove any air bubbles trapped between the first lens and the adhesive layer and any void volume disposed between the first lens and the adhesive layer by applying mechanical pressure.

[0091] In some applications, the one or more mechanical pushing elements are configured to remove any air bubbles trapped between the second lens and the adhesive layer and any void volume disposed between the second lens and the adhesive layer by applying mechanical pressure.

[0092] In some applications, the device further comprises a heating chamber and / or a pressure chamber configured to remove any air bubbles trapped between the first lens and the adhesive layer, any air bubbles trapped between the second lens and the adhesive layer, any void volume disposed between the first lens and the adhesive layer, and any void volume disposed between the second lens and the adhesive layer.

[0093] In some applications, the thickness of the adhesive layer is between 20 micrometers and 300 micrometers.

[0094] In some applications, the thickness of the adhesive layer is between 50 micrometers and 200 micrometers.

[0095] In some applications, the apparatus further comprises a heating component configured to heat at least one element selected from the group consisting of: the second lens, the first lens, the adhesive layer, the first pressure chamber, the second pressure chamber, and any combination thereof, during one or more stages of the adhering.

[0096] In some applications, the heating component is configured to heat the at least one element to a temperature comprised between 25 degrees Celsius and 75 degrees Celsius.

[0097] In some applications, the heating component is configured to heat the at least one element for a time period comprised between 0.1 seconds and 1 hour.

[0098] In some applications, at least one of the mechanical pushing elements is made of a material having a hardness less than 90 Shore A.

[0099] In some applications, at least one of the mechanical pushing elements is made of a material having a hardness comprised between 20 Shore A and 85 Shore A.

[0100] The application will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0101] Figure 1 is a graph showing the stress-time curve and the strain-time curve of a viscoelastic material loaded by a sinusoidal load and responding with a delayed sinusoidal displacement, as known in the prior art and described above in the background section;

[0102] Figure 2 is a schematic view of a pair of glasses comprising one or more lenses consisting of a base lens and an additional lens adhered to the base lens, according to some applications of the present application;

[0103] Figure 3A and Figure 3B is a graph showing the storage modulus, the loss modulus and the tangent of the loss angle as a function of temperature of the respective typical material of which the additional lens is made, according to some applications of the present application;

[0104] Figure 4 is a flow chart summarizing the steps typically performed, according to some applications of the present application;

[0105] Figure 5 and Figure 6 is a schematic view of an apparatus for shaping a lens when the lens is heated to a given temperature, according to some applications of the present application;

[0106] Figure 7A , Figure 7B , Figure 7C and Figure 7Dis a schematic of the various steps of the adhesion process for adhering an additional lens to a base lens according to some applications of the invention;

[0107] Figure 8 is a schematic of a chamber for applying heat and / or pressure to the combined additional lens and base lens after the additional lens and the base lens are adhered to each other according to some applications of the invention; and

[0108] Figure 9A and Figure 9B is a graph demonstrating how a tolerance measurement is performed on a lens manufactured according to some applications of the invention. DETAILED DESCRIPTION

[0109] Reference is now made to Figure 2 , Figure 2 is a schematic of a pair of eyeglasses 18 according to some applications of the invention, the eyeglasses 18 including one or more combined lenses 20 within an eyeglass frame 21, the combined lenses being composed of a base lens 22 and an additional lens 24 adhered to the base lens. For some applications, the combined lens 20 is a progressive lens, where the base lens 22 is a single-vision corrective lens (e.g., a distance-vision corrective lens), and the optical design of the additional lens 24 is such that upon adhering to the base lens 22, the combined lens 20 becomes a progressive lens matching a desired prescription. Typically, the additional lens 24 is coupled to the inner surface of the base lens 22 (i.e., the surface of the base lens 22 that is closer to the user’s eye when the combined lens 20 is incorporated into eyeglasses worn by the user, and this surface is typically concave). Alternatively, the additional lens 24 is coupled to the outer surface of the base lens 22 (i.e., the surface of the base lens 22 that is further from the user’s eye when the combined lens 20 is incorporated into eyeglasses worn by the user, and this surface is typically convex). Note that in Figure 2 the magnified portion, a gap is shown between the outer edge of the additional lens and the eyeglass frame 21. Typically, such a gap does not actually exist, and such a gap is shown in Figure 2 for illustration purposes, in order to show the additional lens 24 and the base lens 22.

[0110] While some applications of the present application are described with reference to the above examples, in which the base lens 22 is a single-vision corrective lens (e.g., a distance-vision corrective lens), and the optical design of the add-on lens 24 is such that, when adhered to the base lens 22, the combination lens 20 becomes a progressive lens matching a desired prescription, the scope of the present application includes applying the lens shaping techniques described herein to other combinations of base lens 22 and add-on lens 24. For example, the lens shaping techniques described herein can be applied to an add-on lens that provides a particular optical function (e.g., polarization, single-vision add-on prescription, etc.), and that is configured to be adhered to a base lens having progressive characteristics. Alternatively, the lens shaping techniques described herein are applied to an add-on lens that is configured to be adhered to a base lens having non-optical corrective characteristics (e.g., a lens of a safety goggle or a swimming goggle). For some applications, the lens shaping techniques described herein are applied to a plano add-on lens that is coated with a functional coating (e.g., any of the functional coatings described below). Alternatively, the lens shaping techniques described herein are applied to an add-on lens that provides an optical function (e.g., a single-vision optical corrective function, a progressive optical corrective function, etc.), and that is configured to be adhered to a base lens that provides sun protection (e.g., UV protection and / or polarization). Moreover, while some applications of the lens shaping techniques are described herein with reference to add-on lenses, the scope of the present application includes applying the shaping processes described herein to any ophthalmic lens having a lens design. As described in further detail below, generally, the techniques described herein are configured to facilitate reshaping of an ophthalmic lens such that, after the lens is reshaped and adhered to a base lens 22, the lens maintains its optical design at predetermined, clinically important sub-regions within ISO standards, and maintains approximately the same residual cylinder at the predetermined, clinically important sub-regions of the lens. Moreover, generally, the lens maintains its original optical design within tolerances at the predetermined sub-regions of the lens without subjecting the ophthalmic lens to significant internal stresses of the type that can cause the add-on lens to crack, or to experience stress cracking during the life of the add-on lens. Further details regarding the lens maintaining its original optical design within tolerances at the predetermined sub-regions of the lens are described below with reference to Figure 3A and Figure 3B Further details regarding the lens maintaining its original optical design within tolerances at the predetermined sub-regions of the lens are described below with reference to

[0111] Reference is now made to Figure 3A and Figure 3B According to some applications of the present application, Figure 3A and Figure 3Bis a plot showing the storage modulus (curve 30), loss modulus (curve 32), and loss tangent (curve 34) of a typical material from which the add-on lens 24 is made as a function of temperature. Typically, the add-on lens 24 is made from an amorphous viscoelastic polymer (e.g., an amorphous thermoplastic polymer) that exhibits both elastic and plastic properties. Further, typically, the add-on lens is made from a polymethyl methacrylate (PMMA) group of polymers (e.g., an impact-modified PMMA polymer) of homopolymers and copolymers. Still further, typically, the material from which the add-on lens is made is selected so that the add-on lens retains its optical design throughout the range of ambient temperatures to which it can be exposed during use of the combination lens 20. Thus, typically, the material is one that does not change shape or crack at temperatures ranging from -10 degrees Celsius to 60 degrees Celsius.

[0112] Figure 3A The curve shown in FIG. 3 was measured on polymethyl methacrylate (PMMA) using dynamic mechanical analysis (also referred to as “DMA analysis”) according to ASTM Number D 5023 (Standard Test Methods for Plastics: Dynamic Mechanical Properties: Bending (Three-Point Bending)), where the analysis was performed using a TGA Q800 TA instrument over a temperature range of 0-200 °C. For some applications, the add-on lens is made from a polycarbonate polymer. Figure 3B The curve shown in FIG. 4 was also measured on a polycarbonate lens using dynamic mechanical analysis according to ASTM Number D 5023 (Standard Test Methods for Plastics: Dynamic Mechanical Properties: Bending (Three-Point Bending)), where the analysis was performed using a TGA Q800 TA instrument over a temperature range of 0-200 °C.

[0113] Figure 3A and Figure 3B The shape of the curve shown in FIG. 3 is a specific example of an amorphous viscoelastic polymer used for some applications according to the present application. However, the scope of the present application includes the use of any amorphous viscoelastic polymer (e.g., any amorphous thermoplastic polymer, and / or any PMMA polymer, polycarbonate polymer, polyurethane, and / or cyclic olefin polymer), and the application of the lens shaping techniques described herein. Other polymers used have different storage modulus curves, loss modulus curves, and loss tangent curves than those shown in FIG. 3. However, the general principles described with respect to FIG. 3 apply to other amorphous viscoelastic polymers. Figure 3A and Figure 3B The curve shown in FIG. 4 has different storage modulus curves, loss modulus curves, and loss tangent curves than those shown in FIG. 3. However, the general principles described with respect to FIG. 3 apply to other amorphous viscoelastic polymers. Figure 3A and Figure 3B The general principles described with respect to FIG. 3 apply to other amorphous viscoelastic polymers. Thus, the general principles of the lens shaping techniques described herein generally apply to other amorphous viscoelastic polymers, but with appropriate temperatures for those materials.

[0114] As described in the Background section above, the response of a viscoelastic material to the application of mechanical energy to the material can be characterized by its storage modulus (E') and its loss modulus (E"). The storage modulus of a material is a measure of its elastic behavior, i.e., the degree to which mechanical energy applied to the material is stored (for release during recovery) in the stretching of bonds along the polymer chains. The loss modulus is a measure of the material's plastic behavior, i.e., the degree to which mechanical energy applied to the material is lost due to internal friction between the polymer chains (this energy is not stored and subsequently released). Another parameter, which is referred to as the material's loss tangent, measures the ratio of the loss modulus to the storage modulus at any temperature. Thus, the loss tangent of a material is a measure of the material's tendency to dissipate and dimensional instability. Typically, all three of the above-mentioned parameters (i.e., the storage modulus, the loss modulus, and the loss tangent) vary as a function of the temperature of the material, as shown by curve 30, curve 32, and curve 34 of FIG. 3. As noted above, these parameters are determined by analyzing the material using dynamic mechanical analysis (also referred to as "DMA analysis"). Figure 3A

[0115] Typically, in accordance with the needs described above, the add-on lens 24 is initially formed to exhibit a given lens optical design (e.g., such that, upon being adhered to the base lens 22, the combination of the base lens and the add-on lens forms a progressive lens). For example, the add-on lens can initially be formed using a forming process such as injection molding, injection compression molding, compression molding, stamping, 3D printing, and / or casting. In order to adhere the add-on lens 24 to the base lens 22, it is typically desirable for the add-on lens to undergo a further shaping process to conform its curvature to that of the base lens. In particular, the surface of the add-on lens that is adhered to the base lens needs to be shaped to conform to the surface of the base lens to which it is adhered. Note that, in some cases, the curvature of the add-on lens is made slightly larger than the curvature of the base lens in order to facilitate the adhesion process described below with reference to FIG. 4. Also, note that, in some cases, and particularly if the curvature of the add-on lens and the curvature of the base lens are similar to each other, it is not necessary to shape the add-on lens prior to the adhesion step. However, the inventors have found that a significant portion of the combination of the add-on lens and the base lens typically requires the shaping technique as described herein to be applied to the add-on lens permanently. This is particularly true when the ophthalmic prescription includes a cylinder with an associated cylinder axis value, the cylinder tending to have an impact on the concave curvature of the base lens. Figure 7A-7D

[0116] ​​An alternative to reshaping the add-on lens to conform its curvature to that of the base lens is to initially shape the add-on lens to have the desired optical design and also to conform to the shape of the base lens. However, this would greatly increase the number of add-on lenses that a retailer or optical lab would need to stock, as it would be necessary to stock separate inventory units of add-on lenses having a given optical design but having different curvatures in order to conform to the respective differently shaped base lenses. (This is particularly true when the ophthalmic prescription includes a cylinder with an associated cylinder axis value, as the cylinder tends to have an impact on the concave curvature of the base lens, as noted above.) Alternatively, this would mean that the add-on lens would have to be manufactured in a custom manner (based on the optical requirements of the patient and the selection of the base lens), in which case many of the advantages of using the base lens and add-on lens rather than using a conventionally manufactured progressive lens would be lost.

[0117] As the predetermined sub-regions of the lens are very precise (on the level of thickness differences in microns), lens shaping is very challenging. Shaping the progressive lens in an uncontrolled manner risks destroying the optical values of the lens. It is desirable that, after the add-on lens is shaped in the manner described above, the add-on lens not only maintains its optical design at the predetermined, clinically important sub-regions within the ISO standard after being reshaped and adhered to the base lens 22, but also maintains approximately the same residual cylinder amount at the predetermined, clinically important sub-regions of the lens. Furthermore, in general, it is desirable to achieve that the lens maintains its original optical design within the tolerances at the predetermined sub-regions of the lens, while the ophthalmic lens does not maintain significant internal stresses (of the type that can cause the add-on lens to crack, or to experience stress cracking during the lifetime of the add-on lens). (Details of the level of tolerance at which the add-on lens should maintain its original optical design at the predetermined sub-regions of the lens will be described in more detail below.) Based on the above considerations, the lens shaping process as described herein is typically applied to the add-on lens 24 after the initial formation of the add-on lens. Figure 9A-9B is described in more detail below.) Based on the above considerations, the lens shaping process as described herein is typically applied to the add-on lens 24 after the initial formation of the add-on lens.

[0118] For some applications, the curvature of the add-on lens can be changed by more than +1 / -1 diopter (e.g., more than +2 / -2 diopters), and / or up to +4 / -4 diopters (e.g., up to +3 / -3 diopters) while maintaining the optical design of the lens and not introducing significant stresses in the lens, by applying the lens shaping process described herein (as described above).

[0119] Referring again to Figure 3A and Figure 3B As noted above, curve 30 shows the storage modulus as a function of temperature, and curve 32 shows the loss modulus as a function of temperature. Again, note that, as Figure 3A and Figure 3BThe curves shown in the middle correspond to the storage modulus, loss modulus, and loss tangent of a particular example of a material that can be used to make an add-on lens. However, the general principles described with reference to Figure 3A and Figure 3B generally apply to any amorphous viscoelastic polymer that can be used to make an add-on lens.

[0120] As noted above, the loss tangent is the ratio between the loss modulus and the storage modulus. Referring first to Figure 3A , curve 34 shows the loss tangent as a function of temperature, which sharply rises before reaching a peak, and then sharply falls. Similarly, referring to Figure 3B , it can be observed that curve 34, which shows the loss tangent as a function of temperature, sharply rises before reaching a peak, and then sharply falls. As shown, the materials typically used for add-on lenses generally have only one peak in their loss tangent / temperature curves.

[0121] The inventors of the present application have discovered that if the add-on lens 24 is shaped at a temperature at which the loss tangent is greater than 0.8 (or in some cases greater than 0.5 or 0.3), this generally causes irreversible damage to the lens optical design. This is because when the lens is shaped under stress at such temperatures, the deformation of the lens generally causes plastic deformation, such that when the lens returns to ambient temperature, the components of the optical design with the lens are lost, and unwanted cylindrical power can appear. On the other hand, the inventors have discovered that if the add-on lens 24 is shaped at a temperature at which the loss tangent is less than 0.2 (and in some cases less than 0.3 or 0.5), this allows the add-on lens to retain its lens optical design, but leaves internal stresses in the lens that can later develop into cracks or regions of the lens that lose transparency due to stress. For example, the lens can form cracks due to the internal stresses in combination with thermal cycling, thermal shock, mechanical shock, or environmental stresses (e.g., due to chemical cleaning materials and / or bodily secreted fluids). The slow crack growth phenomenon of polymers, and in particular amorphous polymers, is well known, and is further accelerated by the fats (e.g., human fat or oil, from the hands or face), oils, cleaners, and soaps that can come into contact with the add-on lens over its lifetime. An additional risk associated with shaping the add-on lens at a temperature at which the loss tangent is less than 0.2 (and in some cases less than 0.5 or less than 0.3) is that the add-on lens will tend to revert to its original shape, which will cause the add-on lens to separate from the base lens.

[0122] According to some applications of the present application, therefore, the additional lens 24 is shaped at a temperature at which the material from which the additional lens is made has a loss tangent greater than 0.2 and / or less than 0.8. For some applications, the additional lens is shaped at a temperature at which the material from which the additional lens is made has a loss tangent of 0.2-0.5 or 0.2-0.3. Alternatively or additionally, the additional lens is shaped at a temperature at which the material from which the additional lens is made has a loss tangent of 0.3-0.8 or 0.5-0.8.

[0123] Note that the loss tangent of a material is typically within the above ranges within the steeply rising portion of the loss tangent / temperature curve and the steeply falling portion of the loss tangent / temperature curve. The material is typically heated to a temperature at which the loss tangent / temperature of the material is within the above ranges within the rising portion of the loss tangent / temperature curve, i.e., below the temperature at which the loss tangent / temperature curve first passes 0.8 (e.g., first passes 0.5 or first passes 0.3). In other words, the additional lens 24 is typically shaped at a temperature that is (a) below the temperature at which the peak of the loss tangent / temperature curve for the material from which the additional lens is made, and (b) at which the loss tangent of the material from which the additional lens is made is greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8). Typically, within the above loss tangent ranges, the material retains its original lens optical design while retaining only low residual stress.

[0124] For some applications, the additional lens is heated to a temperature within the above ranges that is additionally at least 5 degrees Celsius (e.g., at least 10 degrees Celsius) below the peak of the loss tangent / temperature curve for the material from which the additional lens is made. In other words, the additional lens 24 is typically shaped at a temperature that is (a) at least 5 degrees Celsius (e.g., at least 10 degrees Celsius) below the peak of the loss tangent / temperature curve for the material from which the additional lens is made, and (b) at which the loss tangent of the material from which the additional lens is made is greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8). Typically, within the above loss tangent ranges, the material retains its original lens optical design while retaining only low residual stress.

[0125] Note that while the temperature to which the additional lens is heated is constrained by the above limitations, the actual value of the loss tangent at the peak of the loss tangent / temperature curve is not a constraint. In other words, the additional lens is typically heated to a temperature at which the material from which the additional lens is made has a loss tangent greater than 0.2 and / or less than 0.8, regardless of the value of the loss tangent at the peak of the loss tangent / temperature curve.

[0126] Reference is now made toFigure 4 , Figure 4 is a flowchart summarizing the steps typically performed to combine an additional lens 24 and a base lens 22 (e.g., both shown in Figure 2 ) in accordance with some applications of the present application.

[0127] In a first step 60, the additional lens 24 is formed to exhibit a given lens optical design (e.g., such that when adhered to the base lens 22, the combination of the base lens and the additional lens forms a progressive lens) in accordance with the needs described above. For example, the additional lens can initially be formed using a forming process such as injection molding, injection compression molding, compression molding, stamping, 3D printing, and / or casting.

[0128] In a second step 62, the additional lens is reshaped by applying pressure to the additional lens for a period of time (as described in more detail below) such that the curvature of the additional lens conforms to the curvature of the base lens 22. Typically, during this step, the additional lens is heated to a temperature as described above. That is, typically, during this step, the additional lens is heated to a temperature at which the material from which the additional lens is made has a loss tangent greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8). Further, typically, during this step, the additional lens is heated to a temperature at which (a) the loss tangent of the material from which the additional lens is made is less than the peak of the loss tangent / temperature curve of the material from which the additional lens is made, and (b) the loss tangent of the material from which the additional lens is made is greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8). Still further, typically, during this step, the additional lens is heated to a temperature at which (a) the loss tangent of the material from which the additional lens is made is at least 5 degrees Celsius (e.g., at least 10 degrees Celsius) less than the peak of the loss tangent / temperature curve of the material from which the additional lens is made, and (b) the loss tangent of the material from which the additional lens is made is greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8). As described above, within the above-described loss tangent ranges, the material from which the additional lens is made typically retains its original lens optical design while only retaining low residual stress.

[0129] Step 62 is described in further detail below with reference to Figure 5 and Figure 6 For some applications, when the additional lens is heated to the above-described temperature ranges, the additional lens is pressed into a mold 40 (e.g., a mold, as shown in Figure 5 and Figure 6 ) using a pressure applying element 42 (also as shown in Figure 5and Figure 6 The pressure applying element is typically made of a soft material. For some applications, the base lens 22 itself is used as the mold. For some applications, the mold and the pressure applying element are disposed within a furnace 44 (also shown in Figure 5 and Figure 6 shown in FIG. 3) in which the additional lens is heated to the above-mentioned temperature range. Note that, in some cases, the curvature of the additional lens is shaped to be slightly larger than the curvature of the base lens, to facilitate the adhesion process described below with reference to Figure 7A-7D In addition, note that, in some cases, and particularly if the curvature of the additional lens and the curvature of the base lens are similar to each other, it is not necessary to shape the additional lens prior to the adhesion step. However, the inventors have found that a significant portion of the combinations of additional lenses and base lenses typically require the shaping techniques as described herein to be applied to the additional lens.

[0130] At a third step 64, once the additional lens is reshaped, the additional lens is adhered to the base lens, for example using a pressure sensitive adhesive, a light-cured liquid adhesive, a light-cured pressure sensitive adhesive, and / or a different adhesive. Step 64 is described in further detail below with reference to Figure 7A-7D .

[0131] For some applications, an optional fourth step 66 is applied. For such applications, after the additional lens is adhered to the base lens, the combined lens is subjected to additional heat treatment, in order to further remove any residual stress that can be present in the additional lens and / or the entire combined structure. Alternatively or additionally, pressure is applied to the combined structure, to ensure that the additional lens and the base lens are in full contact with each other, without any space or air bubbles between the two. Step 66 is described in further detail below with reference to Figure 8 .

[0132] Reference is now made to Figure 5 , Figure 5 is a schematic illustration of an additional lens 24 being shaped according to some applications of the present application, while the additional lens 24 is heated to a temperature at which the material from which the additional lens is made has a loss tangent greater than 0.2 and / or less than 0.8. As described above, typically, the additional lens 24 is initially formed to exhibit a given lens optical design (e.g., such that the combination of the base lens and the additional lens forms a progressive lens, as shown in Figure 2 For example, the additional lens can be initially formed using a forming process such as injection molding, injection compression molding, compression molding, stamping, 3D printing, and / or casting. In order to adhere the additional lens 24 to the base lens 22, the additional lens typically needs to undergo a further shaping process, to conform its curvature to the curvature of the base lens.

[0133] For some applications, when the additional lens 24 is heated to a temperature falling within the above-mentioned temperature range, a further shaping process is applied to the additional lens such that the curvature of the additional lens conforms to the curvature of the base lens 22 (which can be an aspheric lens). For some applications, the further shaping process comprises pressing the additional lens into a mold 40 (e.g., a mold) using a pressure-applying element 42, which is typically made of a soft material. Typically, the soft material is an elastomer having a hardness less than 90 Shore A (e.g., between 20 Shore A and 85 Shore A). Alternatively or additionally, the soft material is a plastic, an elastomer foam, a porous plastic, a porous elastomer, a liquid-filled bag, an air-filled bag, a multi-layer or single-layer, and / or a gel. For some applications, the soft material is one or more of a silicone elastomer, a polyurethane elastomer, a thermoplastic elastomer, a vulcanized elastomer, and / or a thermoplastic vulcanizate (TPV). For some applications, the pressure-applying element is a dome-shaped pad comprising one or more of the above-mentioned materials. For some applications, the pad has an alternative shape. For some applications (not shown), the base lens 22 itself (shown in Figure 2 ) is used as the mold.

[0134] For some applications, the mold and pressure-applying element are disposed within an oven 44, within which the additional lens is heated to a temperature falling within the above-mentioned temperature range. For some applications, the curvature of the additional lens is made slightly larger than the curvature of the base lens to facilitate the adhesion process described below with reference to Figure 7A-7D As mentioned above, in some cases, and particularly if the curvature of the additional lens and the curvature of the base lens are similar to each other, it is not necessary to shape the additional lens prior to the adhesion step. However, the inventors have found that a significant portion of combinations of additional lenses and base lenses typically require the shaping technique as described herein to be applied to the additional lens.

[0135] Typically, the pressure applied to the additional lens in the shaping process is greater than 0.01 kg per square centimeter (e.g., greater than 0.2 kg per square centimeter) and / or less than 100 kg per square centimeter (e.g., less than 1 kg per square centimeter), e.g., 0.01-100 kg per square centimeter, or 0.2-1 kg per square centimeter. Typically, applying less pressure than the foregoing range is insufficient to cause shaping of the lens, while applying more pressure than the foregoing range can cause damage to the lens (and / or coatings on the lens, such as those described below). For some applications, the duration of time during which the additional lens is heated and pressure is applied to the additional lens is more than 0.1 seconds and / or less than 1 hour, e.g., 0.1 seconds-1 hour. Typically, applying pressure for less than the foregoing range of time will be insufficient to cause reshaping of the lens, while applying pressure for more than the foregoing range of time can cause loss of the optical design of the lens (e.g., due to creep).

[0136] It is noted that due to the reshaping of the lens being performed at a temperature below the peak of the tangent loss curve, in some cases, even after the above-described process is performed, the shape of the additional lens slightly returns to its original shape. Typically, even in such cases, the subsequent steps of the process described below (e.g., the adhesion process described with reference to Figure 7A-7D ensure that the additional lens conforms to the shape of the base lens in a permanent manner.

[0137] Typically, after the shaping process, the lens is cooled before it is removed from the mold (e.g., the mold) in which the lens was placed during the shaping process. Once the additional lens is shaped, the additional lens is adhered to the base lens, for example, using a pressure sensitive adhesive, a light-cured liquid adhesive, a light-cured pressure sensitive adhesive, and / or a different adhesive. For some applications, the additional lens is adhered to the base lens using the adhesion process described below with reference to Figure 7A-7D It is noted that due to the reshaping of the additional lens prior to adhering the additional lens to the base lens, the properties of the reshaped additional lens can be tested prior to the additional lens being adhered to the base lens. In such cases, if it is found that the reshaping process has reduced the fidelity of the optical design of a particular additional lens to a level that is beyond the necessary tolerance, the additional lens can be rejected without causing the base lens to also be rejected.

[0138] For some applications, the additional lens is coated with a functional coating, for example, a hard coating, an anti-reflective coating, a super-hydrophobic coating, an anti-static coating, a cleaning coating (i.e., a coating configured to repel liquids, dust, etc.), a blue light filter, a reflective coating, an anti-UV coating, a photochromic coating, a polarizing coating, and / or any combination thereof. Depending on the respective application, the coating is typically applied to the additional lens in a liquid, a gas, and / or a solid form using techniques known in the art. Typically, the coating is applied to the additional lens prior to the shaping process being applied to the additional lens, and the material from which the coating is made is selected such that when the additional lens is heated to the above-described temperature range and the shaping process is applied to the additional lens, the coating also becomes deformable in a manner that does not cause a loss of functionality of the functional coating, does not introduce significant stress to the coating (the type of stress that can cause the coating to crack or experience stress cracking during the lifetime of the coating), or does not introduce significant stress to the additional lens itself (the type of stress that can cause the additional lens to crack or experience stress cracking during the lifetime of the additional lens). Thus, the curvature of the functional coating can also be changed without causing a loss of functionality of the functional coating. For some applications, the temperature to which the additional lens is heated is such that at that temperature, the tangent loss of the material from which the functional coating is made is greater than 0.2 and / or less than 0.8 (e.g., 0.2-0.8, 0.2-0.5, 0.2-0.3, 0.3-0.8, or 0.5-0.8).

[0139] For some applications, the functional coating is a hard coating, and the selection of the material from which the hard coating is made and the shaping process are such that the hard coating is reshaped without cracking the hard coating, without introducing significant stresses into the hard coating (the type of stress that can cause the hard coating to break or experience stress cracking during the hard coating's lifetime), and without introducing significant stresses into the additional lens itself (the type of stress that can cause the additional lens to break or experience stress cracking during the additional lens's lifetime).

[0140] In general, the coating is selected so that it does not change shape or crack over the temperature range that the lens of the eyeglasses can typically be subjected to during use (e.g., from -10 degrees Celsius to 60 degrees Celsius).

[0141] By selecting the material from which the coating is made in the manner described above, the coating can be applied to the additional lens at a first point in the manufacture of the combination lens 20, and then the shaping process can be applied to the lens and the coating at a different point in the manufacture of the combination lens 20. For example, the coating can be applied to the additional lens 24 at one manufacturing point in the mass production of additional lenses, and then the shaping process can be applied to the lens and the coating at a point of sale. For some such applications, the combination lens 20 is a progressive lens that is manufactured at the point of sale by combining a base lens 22 (which is a single-vision optical corrective lens) with an additional lens 24 (which provides additional optical corrective functionality to the base lens) in accordance with a patient's prescription. For example, the base lens can be a single-vision optical corrective lens, and the additional lens can provide additional optical corrective functionality to the base lens such that the combination of the base lens and the additional lens provides a progressive lens that matches the patient's prescription (e.g., as generally described in Arieli, U.S. 9,995,948, which is incorporated by reference herein).

[0142] For some applications, the additional lens 24 is a planar lens that is coated with one or more functional coatings. For some such applications, the coated planar lens is applied to the base lens 22 that is a progressive lens. For example, the base lens 22 can be a progressive lens that is manufactured using a direct-to-lens surfacing manufacturing process (e.g., a freeform mold manufacturing process). Typically, such progressive lenses are manufactured in a customized manner to match a given patient’s prescription. When a progressive lens is manufactured using a direct-to-lens surfacing manufacturing process, the surface (typically the back surface) of the progressive lens is cut during the manufacturing process. Typically, a functional coating can only be applied to this surface after the cutting is complete, because if the functional coating is to be applied to this surface before the cutting is complete, the coating will be destroyed by the cutting. Applying a functional coating to a cut surface using conventional techniques typically delays the manufacturing process for such lenses, since a time-consuming chemical process is used (and can only be applied after the lens is cut to match the patient’s prescription). This creates a bottleneck in the manufacturing of progressive lenses, which in turn means that such lenses are typically manufactured off-site in a laboratory, rather than on-site at an eyewear factory. For some applications of the present invention, using the techniques described above, a planar additional lens that is pre-coated with one or more functional coatings is shaped to precisely conform to the curvature of the cut surface of a base progressive lens. Typically, the techniques described below with reference to Figure 7A-7D are then used to adhere the planar additional lens to the cut surface of the base progressive lens.

[0143] Note that, typically, the surface of a progressive lens (in particular, the cut surface of a progressive lens that is manufactured using a direct-to-lens surfacing manufacturing process) has a highly complex curvature. However, using the techniques described herein, the additional lens can be reshaped so as to substantially conform to the curvature of the cut surface, without introducing substantial stresses (and any resulting optical distortions) to the additional lens or the functional coatings. For some applications, techniques similar to those described in the paragraph above are applied to base progressive lenses that are manufactured using manufacturing processes other than a direct-to-lens surfacing manufacturing process.

[0144] Reference is now made to Figure 6 , Figure 6 is a schematic illustration of an additional lens 24 being shaped in accordance with some alternative applications of the present invention, while the additional lens 24 is heated to a temperature at which the material from which the additional lens is made has a loss tangent greater than 0.2 and / or less than 0.8. The apparatus and methods used in conjunction with the apparatus shown in Figure 6 are generally similar to the apparatus and methods described above with reference to Figure 5 .

[0145] Although Figure 5A pressure applying element 42 is shown disposed above the mold 40 such that the pressure applying element pushes the additional lens toward the mold in a downward direction, but for some applications, the pressure applying element 42 is disposed below the mold 40 such that the pressure applying element pushes the additional lens toward the mold in an upward direction, as shown in Figure 6

[0146] For some applications, the curvature of the mold 40 is greater than the curvature that the additional lens is to be formed into. Thus, the degree to which the additional lens is reshaped is generally controlled by the amount of pressure that the pressure applying element applies to the additional lens, rather than being limited to the particular curvature of the mold. This is shown schematically in Figure 6 Figure 6 A gap between the additional lens 24 and the mold 40 is shown, at the center of the additional lens, even after the additional lens has been reshaped. Generally, this reduces contact between the additional lens and the mold, and thus potential damage that can result from contact between the additional lens and the mold, relative to if the additional lens were to be formed by pushing the additional lens such that the additional lens is in full contact with the mold. In addition, a single mold can thus be used to produce a wide range of additional lens curvatures.

[0147] As mentioned above, typically, during the forming step, the additional lens is disposed within an oven 44 in order to maintain the temperature of the additional lens at a temperature falling within the above-mentioned temperature range. For some applications, in addition to or in place of the oven that heats the additional lens during the forming process, the additional lens is directly heated in order to maintain precise control over the temperature to which the additional lens is to be heated. For some applications, the additional lens is directly heated via the pressure applying element 42. For example, as shown, an electric heating element 45 can be embedded within the pressure applying element. Alternatively or additionally, a heated fluid can be disposed within the pressure applying element. For some applications, the additional lens is directly heated by the heated mold 40, which is typically made of glass. Alternatively or additionally, the additional lens is directly heated using infrared radiation.

[0148] As mentioned in the paragraph above, for some applications, an electric heating element 45 is embedded within the pressure applying element and is configured to directly heat the additional lens during the forming step. For some applications, the heating element is shaped in a spiral, as shown. In addition, for some applications, the spiral is shaped such that the gap between adjacent windings of the spiral decreases from the center of the spiral toward the outside of the spiral. Generally, this shape of the heating element provides relatively uniform heating across the surface of the additional lens. For some applications, different techniques are used to directly heat the additional lens in a relatively uniform manner (e.g., using a heated fluid disposed inside the pressure applying element, as mentioned above).

[0149] ​​With the above features in mind, such as the direct heating of the additional lens using the pressure application element, and the materials, shapes, and designs described with reference to the pressure application element 42, can be incorporated into other components described herein, such as, for example, Figure 5 the pressure application element 42 and / or Figure 7A-7D the push element 80 as shown.

[0150] Reference is now made to Figure 7A , Figure 7B , Figure 7C and Figure 7D which are schematic illustrations of various steps of an adhering process for adhering the additional lens 24 to the base lens 22 in accordance with some applications of the present application. Generally, the steps shown in Figure 7A-7D are performed after the additional lens has been reshaped so that its curvature conforms to that of the base lens. Generally, the additional lens defines at least one convex surface, and the base lens defines at least one concave surface, and the convex surface of the additional lens is adhered to the concave surface of the base lens. For some applications, when reshaping the additional lens (e.g., using the techniques described above), the convex surface of the additional lens is made to have a curvature that is slightly greater than the curvature of the concave surface of the base lens, so as to facilitate the techniques described with reference to Figure 7A-7D (especially the steps described with reference to Figure 7C ).

[0151] For some applications, as shown in Figure 7A the additional lens 24 is held in a first chamber 71, while the base lens 22 is held in a second chamber 72. For some applications, each of the chambers 71 and 72 functions as an oven, as the temperature of each chamber can be controlled. Alternatively, the chambers are not heated. Generally, the chamber 71 is coupled to a vacuum pressure source via a first tube 70, and the chamber 72 is coupled to the same or an alternative vacuum pressure source via a second tube 75, such that the pressure within each chamber can be controlled independently of one another.

[0152] Generally, a thin flexible adhesive layer 73 (which is generally a pressure sensitive adhesive, with adhesive on both sides thereof) is held between the two chambers. For example, as shown in a cross-sectional view of the chambers, the adhesive layer 73 can be held between the first and second chambers by a solid plate 79. Generally, the adhesive layer has a uniform thickness, which is generally greater than 20 microns (e.g., greater than 50 microns) and / or less than 300 microns (e.g., less than 200 microns) (e.g., 20-300 microns, or 50-200 microns). For some applications, the adhesive layer is adhered to the chambers (e.g., the solid plate 79) on both sides thereof, such that the adhesive layer is held in place by the chambers. Figure 7A-7DThe steps shown involve controlling the pressure within the chambers and moving the lens toward the adhesive layer, allowing the additional lens to adhere to the base lens via adhesive layer 73 without leaving noticeable air bubbles or other spaces between either lens and the adhesive layer. Typically, a vacuum pressure (e.g., a negative pressure between 1 mbar and 1 bar) is generated in each chamber for most of the process to reduce the pressure below ambient pressure. At certain stages of the process, the pressure in one or both chambers may be increased or decreased, as described below. For some applications, one or both lenses, and / or the adhesive layer, and / or one or both pressure chambers are heated during one or more stages of the adhesion process.

[0153] The convex surface of the additional lens has a central region 76. For example... Figure 7B As shown, for some applications, a pressure difference is created between chambers 71 and 72, causing the adhesive layer to form a convex curve facing the convex surface of the additional lens, such that the central region 74 of the adhesive layer is closer to the central region 76 of the convex surface of the additional lens than any other two points on the convex surface of the adhesive layer and the additional lens. As mentioned above, the pressures within chambers 71 and 72 are typically controlled independently. For some applications, at this stage, the pressure in chamber 71 is lower than the pressure in chamber 72 so that the adhesive layer bends in the manner described above.

[0154] When the adhesive layer bends toward the additional lens, a mechanical actuating element 80 is used, for example, to orient the additional lens and the adhesive layer toward each other. For some applications, the mechanical actuating element 80 has the same characteristics as described above. Figure 5-6 The pressure application element 42 shown has a substantially similar shape, size, and / or function to those described. For some applications, as shown, the actuating element is a dome-shaped actuating element hydraulically controlled using piston 81. Typically, the adhesive layer 73 and the additional lens 24 initially contact each other at their respective central regions 74 and 76. As the additional lens continues to be brought toward the adhesive layer, the contact between the additional lens and the adhesive layer radiates outward from the central region 76 of the convex surface of the additional lens until the convex surface of the additional lens is completely covered by the adhesive layer. Note that for some applications, the adhesive layer is not formed to bend toward the additional lens. However, due to the convex curvature of the convex surface of the additional lens, the first point of contact between the additional lens and the adhesive layer is typically at the center of the additional lens. Typically, by having the additional lens first contact the adhesive layer at its center and then having the contact between the additional lens and the adhesive layer radiate outward, air bubbles are expelled from between the additional lens and the adhesive layer, thereby substantially preventing air bubbles from becoming trapped between the additional lens and the adhesive layer.

[0155] For some applications, a vacuum pressure is established in at least the first chamber 71 (i.e., the pressure within the first chamber is made less than the ambient pressure) prior to bringing the additional lens and the adhesive layer toward one another, so as to remove air bubbles from between the adhesive layer and the additional lens. The establishment of the vacuum pressure within the first chamber is typically performed regardless of whether a pressure differential is established between the first and second chambers at this stage (i.e., in order to bend the adhesive layer, as described above). For some applications, after the adhesive layer is adhered to the additional lens, the pressure within the chambers 71 and / or 72 is increased (e.g., to the ambient pressure) in order to remove any small air bubbles that can still have become trapped between the additional lens and the adhesive layer, and / or any voids that can be located between the additional lens and the adhesive layer. The increase in pressure typically causes any small air bubbles that can have become trapped between the additional lens and the adhesive layer to seep out from between the additional lens and the adhesive layer, and causes any voids that can be located between the additional lens and the adhesive layer to be removed by applying pressure to the adhesive layer.

[0156] With reference to Figure 7C and Figure 7D After the adhesive layer 73 is adhered to the additional lens 24, the additional lens and the adhesive layer are brought toward the base lens 22 (e.g., using the mechanical pushing element 80). For some applications, a vacuum pressure is established in at least the second chamber 72 (i.e., the pressure within the second chamber is made less than the ambient pressure) prior to bringing the additional lens and the adhesive layer toward the base lens, so as to remove air bubbles from between the adhesive layer and the base lens. As described above, typically, during the reshaping of the additional lens, the convex curvature of the surface of the additional lens that is to be adhered to the adhesive layer is made greater than the concave curvature of the surface of the base lens that is to be adhered to the adhesive layer. Thus, the respective shapes of the additional lens and the base lens are typically such that the first point of contact between the adhesive layer (which at this stage conforms to the shape of the additional lens) and the base lens is at the central region 77 of the concave surface of the base lens 22 (as shown in FIG. 8A). As the additional lens continues to be pushed toward the base lens, the contact between the adhesive layer and the base lens radiates outward from the center of the concave surface of the base lens, until the concave surface of the base lens is completely covered by the adhesive layer (as shown in FIG. 8B). Typically, by having the base lens first contact the adhesive layer at its center, and then having the contact between the base lens and the adhesive layer radiate outward, air bubbles are squeezed out from between the base lens and the adhesive layer, thereby substantially preventing air bubbles from becoming trapped between the base lens and the adhesive layer. Figure 7C Figure 7D

[0157] ​​For some applications, to remove any small air bubbles that can still have become trapped between the base lens and the adhesive layer, and / or any voids that can be located between the additional lens and the adhesive layer, the pressure within the chamber 71 and / or 72 is increased (e.g., to ambient pressure). The increase in pressure typically causes any small air bubbles that can have become trapped between the base lens and the adhesive layer to escape, and causes any voids that can be located between the additional lens and the adhesive layer to be removed. Alternatively or additionally, a mechanical pressure is applied to one or both sides of the combined lens (e.g., using the mechanical pushing element 80 and / or an additional pushing element configured to push the outer surface of the base lens 22), so as to cause any small air bubbles that can have become trapped between the additional lens and the adhesive layer and / or between the base lens and the adhesive layer to escape, and / or so as to remove any voids that can be located between the additional lens and the adhesive layer and / or between the base lens and the adhesive layer. Additionally, alternatively or additionally, the combined lens is transferred to a separate chamber for applying heat and pressure to one or both sides of the combined lens (e.g., as shown in FIG. 8). Figure 8

[0158] As described above, for some applications, each of the chamber 71 and the chamber 72 functions as an oven, as the temperature of each chamber can be controlled. For some applications, additional elements within the chamber, such as the pushing element 80, can be temperature controllable. For some applications, during one or more of the steps described with reference to FIGS. 6-7, the base lens, the additional lens, the adhesive layer, the first pressure chamber, and / or the second pressure chamber are heated. For example, one or more of the above-described elements can be heated to a temperature between 25 degrees Celsius and 75 degrees Celsius. Figure 7A-7D

[0159] Note that, although Figure 7A-7D the arrangement shown in FIG. 6 is shown as applying the adhesive layer to the additional lens first and then applying the adhesive layer to the base lens, the scope of the present application includes applying the adhesive layer to the base lens first and then applying the adhesive layer to the additional lens. Similarly, although Figure 7A-7D the arrangement shown schematically in FIG. 7 shows the additional lens disposed under the adhesive layer and the base lens, the scope of the present application includes performing a substantially similar technique, but using the base lens disposed under the adhesive layer and the additional lens, and / or using the base lens, the adhesive layer, and the additional lens disposed side-by-side with each other, and / or a different arrangement.

[0160] For some applications, the computer processor 82 is configured to perform the steps described with reference to FIGS. 6-7. Figure 7A-7D ​​One or more of the steps described, the computer processor 82 is configured to control the pressure in the pressure chamber, and / or control the movement of a mechanical element (e.g., a mechanical pushing element). Generally, the operations described herein as being performed by the computer processor 82 transform the physical state of the memory, according to the memory technology used, to have different magnetic polarities, charges, etc., that are physically realizable in the memory, which is a real physical artifact that is in communication with the computer processor. The computer processor is generally a hardware device programmed with computer program instructions to produce a special purpose computer. For example, when programmed to perform the techniques described herein, the computer processor generally acts as a special purpose lens adhering computer processor.

[0161] Referring now to Figure 8 , Figure 8 is a schematic illustration of a chamber 90 according to some applications of the present application, into which the combined lens 20 is transferred after the additional lens 24 has been adhered to the base lens 22. Generally, heat and / or pressure is applied to the combined lens within the chamber 90. For some applications, as shown, the combined lens is placed within a container 92. An upper cover 94 is configured to cover the container to form a sealed interior chamber within which the combined lens is disposed. A seal 96 (e.g., an O-ring) is generally disposed between the upper cover and the container so as to seal the interface therebetween. For some applications, once the sealed interior chamber has been formed, pressure is applied to the outer surface of the combined lens, for example by applying pressure by pumping air into the sealed interior chamber via an air inlet tube 97. Generally, pressure is applied so as to cause any small air bubbles that can have become trapped between the additional lens and the base lens (e.g., between the additional lens and the adhesive layer and / or between the base lens and the adhesive layer) to escape, and / or so as to remove any void volume that can be located between the additional lens and the base lens (e.g., between the additional lens and the adhesive layer and / or between the base lens and the adhesive layer).

[0162] For some applications, the chamber 90 is an oven, whereby the temperature within the chamber is controlled. Alternatively or additionally, one or more surfaces in contact with the combined lens (e.g., the interior surfaces of the container 92 and / or the upper cover 94) are used to directly apply heat to the combined lens, for example to control the temperature to which the combined lens is heated during this stage. Additionally, alternatively or additionally, the air used to apply pressure to the combined lens is heated to control the temperature to which the combined lens is heated during this stage. Generally, the combined lens is heated to a temperature to eliminate any residual stress in one or both lenses that can cause the lens to degrade over time.

[0163] Tolerance measurement

[0164] As noted above, it is generally desirable that, after the additional lens 24 has been reshaped in the manner described above, the additional lens not only maintains the optical design of the base lens 22 at the predetermined measurement regions within the ISO standards after it has been reshaped and adhered to the base lens 22, but also maintains approximately the same residual cylinder amount at the predetermined, clinically important regions of the lens. The maintenance of the optical design of the additional lens is generally measured using the following techniques:

[0165] Assuming that the vision correction prescription of the individual patient contains a prescribed amount of spherical correction in diopters, cylinder correction in diopters, a prescribed cylinder axis direction in degrees, and an add value in diopters, the additional lens needs to be reshaped to conform to the curvature of the base lens 22. The base lens typically has a spherical or aspherical front surface, a toric, spherical non-toric or aspherical back surface, a specific center thickness, and a specific index of refraction. The base lens is typically selected so that its optical spherical and cylinder prescriptions approximate the patient's target prescription to within the ISO standards. The additional lens is typically adhered to the base lens in such a way that, prior to the lenses adhering to each other, the base lens is rotated relative to the additional lens by an angle specified by the patient's cylinder axis prescription to within the accuracy of the ISO standards. The adherence is typically such that the combined lens 20, when assembled in the frame in the correct orientation, has the following properties:

[0166] • the difference between the spherical value of the lens 20 and the patient's target spherical Rx value is within the ISO standards when measured at the distance reference position of the lens 20 with an ISO adjusted measurement device.

[0167] • the difference between the cylinder value of the lens 20 and the patient's target cylinder Rx value is within the ISO standards when measured at the distance reference position of the lens 20 with an ISO adjusted measurement device.

[0168] • the difference between the cylinder axis value of the lens 20 and the patient's target cylinder axis Rx value is within the ISO standards when measured at the distance reference position of the lens 20 with an ISO adjusted measurement device.

[0169] • the difference between the add value of the lens 20 (the mean-power value measured at the near reference position of the lens 20) and the patient's target add value Rx value is within the ISO standards when measured with an ISO adjusted measurement device.

[0170] Those familiar with ophthalmic lens design techniques know that a common approach in evaluating the optical performance of an ophthalmic lens is to divide the entire ophthalmic lens area into a number of small sub-areas and to study the residual sphere, cylinder and cylinder axis values for each sub-area separately. These sub-areas are typically measured on the order of four millimeters in spatial extent and can be circular in shape or rectangular in shape. The residual sphere and cylinder of the lens in each such sub-area is a value that is obtained by measuring the optical properties of the lens in each sub-area and subtracting the patient's Rx from these values. Since the patient's Rx and the optical correcting properties of the lens are not scalars or vectors, these values can be mathematically calculated using the following equations:

[0171]

[0172] Here, m L (x,y) is the spherical cylinder matrix of the lens measured in a sub-area centered at location (x,y), S(x,y) is the spherical power of the lens measured for the sub-area, C(x,y) is the cylinder of the lens measured for the sub-area, and Ax(x,y) is the cylinder axis of the lens measured for the sub-area.

[0173] Similarly, the patient's Rx can be represented by the Rx spherical cylinder matrix

[0174] The residual sphere and cylinder values of the lens sub-area with respect to the patient's Rx are obtained in the following manner:

[0175] a. Calculate the residual spherical cylinder matrix m Res (x,y) = m L (x,y) - m Rx .

[0176] b. Find the eigen values and corresponding eigen directions of the matrix m Res .

[0177] c. In the cylinder minus convention, the residual sphere value of the sub-area is the most positive eigen value of the matrix, the residual cylinder value is the difference between the smallest positive eigen value and the most positive eigen value, and the cylinder axis is the eigen direction of the most positive eigen value.

[0178] There are many progressive lens designs on the market, designed by several different lens design suppliers. These lens designs differ from each other in the values of their residual optical properties over many of their sub-regions, when the Rx of the patient for which the reference lens was designed to correct is taken into account. The most common parameter to distinguish progressive lens designs is the length of the power progression. Broadly speaking, this value measures how many millimeters are needed along the channel for the average power to rise from the distance value at the distance reference position to its target add value.

[0179] According to some applications of the present invention, the additional lens, after being reshaped and adhered to the base lens 22, not only maintains its optical design (as described above) at the predetermined measurement locations, but also maintains approximately the same residual cylinder amount in predetermined, clinically important regions of the lens.

[0180] In particular, there are measurement procedures that can be applied to the additional lens 24 and to the combined lens 20 composed of the additional lens and the base lens 22. These procedures measure the optical properties over a large portion of the sub-regions of the lens. From these measurements, it is easy to calculate a map of residual properties for each lens and then compare one map to the other using different quantity metrics in different regions. The residual properties of the additional lens are calculated with respect to a patient having zero spherical and cylinder correction, while the residual properties of the combined lens are calculated with respect to a patient having a given target Rx, for which the base lens typically corrects. For example, one quantity metric can be defined in the following way: calculate the distance in millimeters that must be traveled to the left and to the right, from the local minimum of the absolute value of the residual cylinder profile, at a Y coordinate equal to the Y coordinate of the myopic reference point, until the threshold of 0.5 D absolute value of the residual cylinder is reached. Then, when the calculation is made for the residual cylinder of the additional lens (before reshaping) and for the absolute value of the residual cylinder of the combined lens 20, the sum of these two distances can be compared. Similarly, such a calculation can be made at 2 mm, 4 mm, 6 mm and 8 mm higher (closer to the fitting point) than the Y coordinate. Typically, when such quantity metrics are calculated for the measured maps of the additional lens (before reshaping) and of the combined lens 20, it has been found that the difference does not exceed 10% for lenses having a spherical power between -2 D and +2 D and a cylinder value between -2 and 0 in negative cylinder format, when the techniques described herein have been applied to the additional lens.

[0181] Reference is now made to Figure 9A and Figure 9B , Figure 9A and Figure 9B are graphs illustrating the above principles. In Figure 9AIn the middle, horizontal tangents are shown at the myopic reference point of the residual cylinder (dashed curve) and the mean power add (solid curve) of the add-on lens being measured, prior to reshaping. The distance in millimeters that must be traversed from the absolute value of the closest channel of the cylinder plot, left and right, until a threshold of 0.5 D of unwanted cylinder is reached can be calculated. These points are labeled as points 50 in the plot. The distance between these two points can be used as a quantitative measure for evaluating the amount of residual cylinder of the lens in the region of the prism reference point. Similarly, the combination lens 20 consisting of the add-on lens 24 and the base lens 22 can be measured and this can be evaluated with the same quantitative measure. This is shown in the middle of Figure 9B As described above, typically, when such a quantitative measure is calculated for the measured plots of the add-on lens (prior to reshaping) and the combination lens 20, it has been found that the difference does not exceed 10% for lenses having a spherical power between -2 D and +2 D and a cylinder value between -2 and 0 in negative cylinder format, when the techniques described herein have been applied to the add-on lens.

[0182] As known to those familiar with the art, high Rx single vision lenses can also exhibit significant residual spherical and cylinder values at sub-regions away from the optical center of the lens when measured with a mapping device. For lenses having a relatively high Rx (spherical less than -2 D or greater than +2 D, and / or cylinder less than -2 D), a modified method must be used to evaluate the optical performance of the combination lens 20 relative to the add-on lens and the base lens, which consists of the following steps:

[0183] 1. Measure the residual optical properties of the preformed add-on lens at each sub-region of the add-on lens and calculate the spherical cylinder matrix m add (x,y) for each sub-region.

[0184] 2. Measure the residual optical properties of the base lens at each sub-region of the base lens and calculate the spherical cylinder matrix m bl (x,y) for each sub-region.

[0185] 3. Calculate the theoretical spherical cylinder matrix m th (x,y) = m bl (x,y) + m add (x,y) for each sub-region, which represents the sum of the residual properties of the base lens and the residual properties of the add-on lens.

[0186] 4. Calculate the residual cylinder C th (x,y) of m th (x,y) at each sub-region as the difference between the smallest positive eigenvalue and the largest positive eigenvalue of m th (x,y).

[0187] 5. The C th (x,y) cylinder of the absolute value is plotted on a graph.

[0188] 6. The residual optical properties of the combination lens are measured at each sub-region of the lens and the spherical cylinder matrix m cl (x,y) is calculated for each sub-region.

[0189] 7. The residual optical cylinder C cl (x,y) at each sub-region is calculated as the difference between the smallest positive eigenvalue and the largest positive eigenvalue of m cl (x,y). cl (x,y).

[0190] 8. The residual cylinder C cl (x,y) obtained in this way is plotted on a graph.

[0191] 9. The above quantity measures of the absolute value of C th (x,y) and the absolute value of C cl (x,y) are calculated at Y, the near reference position, and at Y coordinates 2 mm, 4 mm, 6 mm and 8 mm higher (closer to the fitting point).

[0192] Generally, when such quantity measures are calculated for the measurement graphs of the additional lens (before reshaping) and the combination lens 20, it has been found that the difference does not exceed 10% when the techniques described herein have been applied to the additional lens.

[0193] Those skilled in the art will realize that the present application is not limited to the particular implementations and examples described herein. The scope of the present application includes combinations and sub-combinations of various features described herein, as well as variations and modifications thereof that will occur to those skilled in the art upon reading the foregoing description, which are not to be regarded as a departure from the spirit and scope of the application.

Claims

1. A method comprising: adhering a first lens to a second lens to form a combined lens having a given optical design, the adhering comprising: placing the first lens and the second lens in corresponding first and second pressure chambers, with an adhesive layer disposed between the first lens and the second lens, pressure within each of the first and second pressure chambers being independently controllable; contacting a convex surface of the first lens with the adhesive layer such that a central region of the convex surface of the first lens first contacts the adhesive layer, and contact between the convex surface of the first lens and the adhesive layer subsequently radiates outward from the central region of the convex surface of the first lens until the convex surface of the first lens is covered by the adhesive layer; and contacting a concave surface of the second lens with the adhesive layer such that a central region of the concave surface of the second lens first contacts the adhesive layer, and contact between the concave surface of the second lens and the adhesive layer subsequently radiates outward from the central region of the concave surface of the second lens until the concave surface of the second lens is covered by the adhesive layer.

2. The method of claim 1, wherein, the adhering further comprising lowering pressure within the first pressure chamber below ambient pressure while contacting the convex surface of the first lens with the adhesive layer.

3. The method of claim 1, wherein, the adhering further comprising lowering pressure within the second pressure chamber below ambient pressure while contacting the concave surface of the second lens with the adhesive layer.

4. The method of claim 1, wherein, contacting the convex surface of the first lens with the adhesive layer such that the central region of the convex surface of the first lens first contacts the adhesive layer comprises causing the adhesive layer to form a convex curve facing the convex surface of the first lens by applying a pressure differential between the first and second pressure chambers.

5. The method of claim 1, wherein, contacting the concave surface of the second lens with the adhesive layer such that the central region of the concave surface of the second lens first contacts the adhesive layer comprises, after the convex surface of the first lens is covered by the adhesive layer, moving the first lens and the adhesive layer and the second lens toward one another such that a central region of the convex surface of the first lens on which the adhesive layer is disposed contacts a central region of the concave surface of the second lens, wherein a curvature of the convex surface of the first lens is greater than a curvature of the concave surface of the second lens.

6. The method of claim 1, further comprising removing any air bubbles trapped between the first lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, heat press treatment, and any combination of these.

7. The method of claim 1, further comprising removing any air bubbles trapped between the second lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, heat press treatment, and any combination of these.

8. The method of claim 1, further comprising removing any void volume located between the first lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, and any combination of these.

9. The method of claim 1, further comprising removing any void volume located between the second lens and the adhesive layer using at least one technique selected from the group consisting of: applying air pressure, applying mechanical pressure, and any combination of these.

10. The method of any one of claims 1-9, wherein, The thickness of the adhesive layer is between 20 microns and 300 microns.

11. The method of claim 10, wherein, The thickness of the adhesive layer is between 50 microns and 200 microns.

12. The method of any one of claims 1-9, further comprising, at one or more stages during the adhering, heating at least one element selected from the group consisting of: the second lens, the first lens, the adhesive layer, the first pressure chamber, the second pressure chamber, and any combination of these.

13. The method of claim 12, wherein, Heating the at least one element comprises heating the at least one element to a temperature between 25 degrees Celsius and 75 degrees Celsius.

14. The method of claim 12, wherein, Heating the at least one element comprises heating the at least one element for a time period of 0.1 seconds to 1 hour.

15. An apparatus for adhering a first lens to a second lens to form a combined lens, the first lens having at least one convex surface, the second lens having at least one concave surface, the combined lens having a given optical design, the apparatus comprising: a first pressure chamber configured to house the first lens and a second pressure chamber configured to house the second lens, the pressure within each of the first pressure chamber and the second pressure chamber being independently controllable; an adhesive layer disposed between the first pressure chamber and the second pressure chamber; one or more mechanical pushing elements; and a computer processor configured to: drive one of the mechanical pushing elements to bring the convex surface of the first lens into contact with the adhesive layer such that a central region of the convex surface of the first lens first contacts the adhesive layer and the contact between the convex surface of the first lens and the adhesive layer subsequently radiates outward from the central region of the convex surface of the first lens until the convex surface of the first lens is covered by the adhesive layer; and drive one of the mechanical pushing elements to bring the concave surface of the second lens into contact with the adhesive layer such that a central region of the concave surface of the second lens first contacts the adhesive layer and the contact between the concave surface of the second lens and the adhesive layer subsequently radiates outward from the central region of the concave surface of the second lens until the concave surface of the second lens is covered by the adhesive layer. The computer processor is configured to lower the pressure within the first pressure chamber below ambient pressure when driving one of the mechanical pushing elements to bring the convex surface of the first lens into contact with the adhesive layer. ​ 16. The apparatus of claim 15, wherein, ​ 17. The apparatus of claim 15, wherein, The computer processor is configured to reduce the pressure within the second pressure chamber below ambient pressure when one of the mechanical pushing elements is actuated to bring the concave surface of the second lens into contact with the adhesive layer.

18. The apparatus of claim 15, wherein, The computer processor is configured to cause the adhesive layer to form a convex curve facing the convex surface of the first lens by applying a pressure difference between the first pressure chamber and the second pressure chamber.

19. The apparatus of claim 15, wherein, The device is for use with a first lens and a second lens, the first lens and the second lens being shaped such that the curvature of the convex surface of the first lens is greater than the curvature of the concave surface of the second lens, and wherein the computer processor is configured to, after the convex surface of the first lens is covered by the adhesive layer, move the first lens and the adhesive layer and the second lens towards each other such that a central region of the convex surface of the first lens on which the adhesive layer is disposed comes into contact with a central region of the concave surface of the second lens.

20. The apparatus of claim 15, wherein, The computer processor is configured to remove any air bubbles trapped between the first lens and the adhesive layer and any void volume disposed between the first lens and the adhesive layer by applying air pressure within the first pressure chamber.

21. The apparatus of claim 15, wherein, The computer processor is configured to remove any air bubbles trapped between the second lens and the adhesive layer and any void volume disposed between the second lens and the adhesive layer by applying air pressure within the second pressure chamber.

22. The apparatus of claim 15, wherein, The one or more mechanical pushing elements are configured to remove any air bubbles trapped between the first lens and the adhesive layer and any void volume disposed between the first lens and the adhesive layer by applying mechanical pressure.

23. The apparatus of claim 15, wherein, The one or more mechanical pushing elements are configured to remove any air bubbles trapped between the second lens and the adhesive layer and any void volume disposed between the second lens and the adhesive layer by applying mechanical pressure.

24. The device of claim 15, further comprising a heating chamber and / or a pressure chamber configured to remove any air bubbles trapped between the first lens and the adhesive layer, any air bubbles trapped between the second lens and the adhesive layer, any void volume disposed between the first lens and the adhesive layer, and any void volume disposed between the second lens and the adhesive layer.

25. The apparatus of any of claims 15-24, wherein, The thickness of the adhesive layer is between 20 micrometers and 300 micrometers.

26. The apparatus of claim 25, wherein, The thickness of the adhesive layer is between 50 micrometers and 200 micrometers.

27. The device of any one of claims 15-24, further comprising a heating component configured to heat at least one element selected from the group consisting of: the second lens, the first lens, the adhesive layer, the first pressure chamber, the second pressure chamber, and any combination of these, at one or more stages of the adhering.

28. The apparatus of claim 27, wherein, The heating component is configured to heat the at least one element to a temperature between 25 degrees Celsius and 75 degrees Celsius.

29. The apparatus of claim 27, wherein, The heating component is configured to heat the at least one element for a time period of 0.1 seconds to 1 hour.

30. The apparatus of any one of claims 15-24, wherein, At least one of the mechanical pushing elements is made of a material having a hardness less than 90 Shore A.

31. The apparatus of claim 30, wherein, The at least one of the mechanical pushing elements is made of a material having a hardness between 20 Shore A and 85 Shore A.

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