Lens element

Abstract

The invention relates to a lens element for being worn in front of an eye of a wearer, the lens element comprising: a substrate having a front end face and a rear end face; and an optical element on one of the front end face or the rear end face of the lens element, the optical element being implemented in the form of a blind hole relative to the end face surface and reducing the contrast on the retina of the wearer, thereby facilitating the control of myopia and improving the comfort of the wearer. Wherein the at least one optical element has a peak valley size (PV) equal to or less than 25 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to a lens element for being worn in front of a person's eyes, in particular for suppressing, slowing down the progression of, or controlling an abnormal refraction of the eyes (such as myopia or hyperopia). The lens element is in particular an ophthalmic article.

[0002] The term "ophthalmic article" is here specifically understood to mean a lens (a corrective lens or other type of lens) that can be used as an eyeglass lens, for example for ordinary glasses, in particular sunglasses, goggles, face masks, etc., or for contact lenses worn by a user in direct contact with their eyes. Background Art

[0003] Myopia of the eyes is characterized by the fact that the eyes focus distant objects in front of the retina of the eyes. Hyperopia of the eyes is characterized by the fact that the eyes focus distant objects behind the retina of the eyes. Concave lenses are typically used to correct myopia, and convex lenses are used to correct hyperopia.

[0004] It has been observed that some individuals (especially children) experience inaccurate focusing when observing objects located at close range when using traditional single - vision lenses for vision correction, that is, under near - vision conditions. Due to this focusing defect in myopic children when correcting their far - vision, even in the macular area, the imaging of nearby objects is formed behind their retina.

[0005] This focusing defect may affect the progression of myopia in these individuals. It has been observed that for the majority of these individuals, this myopia defect tends to increase over time.

[0006] Macular vision corresponds to the observation condition under which the eyes focus the imaging of the object being observed on the central area of the retina called the macular area.

[0007] Peripheral vision corresponds to the perception of elements in the scene that are laterally offset relative to the object being observed, and the imaging of these elements is formed on the peripheral part of the retina away from the macular area.

[0008] Ophthalmic correction measures provided for patients with refractive errors are usually applicable to their macular vision. However, it is well known that the amount of correction for peripheral vision needs to be reduced relative to the amount of correction determined for macular vision. In particular, studies on monkeys have shown that even if light is perfectly focused on the fovea simultaneously, focusing light far behind the peripheral retina can cause the eye to elongate and thus lead to an increase in the myopia defect.

[0009] Therefore, there is a need for a lens element that can suppress, control, or at least slow down the progression of abnormal refraction of the eyes (such as myopia or hyperopia).

[0010] WO2019206569, published in the name of the applicant, proposed a solution, that is, a lens element was disclosed, which has optical elements that particularly provide a focus shift function so as not to focus imaging on the peripheral retina of the eye under standard wearing conditions.

[0011] However, it has been observed that some lenses equipped with dot lens elements (for myopia control) present an unpleasant white foggy visual perception from the perspective of an observer. This white foggy effect can be easily seen when these lens elements are placed on a colored surface or a dark background, for example, when glasses equipped with such lens elements are placed on a dark table or on someone's skin.

[0012] The present disclosure aims to provide an improved lens element that shows at least a reduced white foggy visual perception or no white foggy visual perception from the perspective of an observer while providing effective myopia or hyperopia control. Summary of the Invention

[0013] To achieve the above object, the present disclosure proposes a lens element for wearing in front of a wearer's eyes, the lens element comprising: a substrate having a front end face and a rear end face; and an optical element located on one of the front end face or the rear end face of the lens element, the optical element being realized in the form of a blind hole with respect to the end face surface and reducing the contrast on the retina of the wearer, thereby contributing to the control of myopia, wherein at least one optical element has a peak-to-valley size equal to or less than 25 μm.

[0014] The present disclosure also proposes a method for manufacturing a lens element for wearing in front of a wearer's eyes, the lens element comprising: a substrate having a front end face and a rear end face; and an optical element located on one of the front end face or the rear end face of the lens element, the optical element being realized in the form of a blind hole with respect to the end face surface and reducing the contrast on the retina of the wearer, thereby contributing to the control of myopia, wherein at least one optical element has a peak-to-valley size equal to or less than 25 μm. The method may include a laser engraving step using a laser whose engraving wavelength is equal to or less than 355 nm, particularly 355 nm or 266 nm.

[0015] According to further aspects considered separately or in combination with respect to the lens element defined above:

[0016] - The optical element may be a blind hole realized by laser ablation.

[0017] - The lens element may further include an anti-reflection coating.

[0018] - The lens element may further include a hard coating having a refractive index of 1.6 ± 2%.

[0019] - The hard coating may include a compound for enhancing laser absorption between 250 nm and 370 nm.

[0020] - In this case, the compound for enhancing laser absorption may include metal oxides or metal-containing colloids.

[0021] - The end face of the lens element, which is present in a region and defined by the optical element, may exhibit a power spectral density of 10 10 nm⁻³ ± 10%.

[0022] - The boundary of at least one blind hole (14) may protrude from the surrounding end surface (16) by less than 5 μm, thereby presenting the optical element (14).

[0023] - An optical element may have a peak-to-valley size equal to or less than 15 μm.

[0024] - The substrate may exhibit 0% transmittance for a 2-mm layer at the ablation wavelength of the laser.

[0025] - The hard coating may have an extinction coefficient (k) higher than 0.005, preferably higher than 0.05, in the wavelength range of 250 - 355 nm.

[0026] - The diameter of the blind hole may be between 170 μm and 220 μm.

[0027] - The spacing between the centers of two adjacent blind holes may be between 300 μm and 420 μm.

[0028] - The haze level of the lens element may be presented as 15% ± 5%.

[0029] - The lens element may include an unengraved circular central region (16C).

[0030] - The unengraved circular central region may have a diameter of 3.5 mm.

[0031] - The unengraved circular central region may be surrounded by an annular region, where the diameter of the blind hole gradually increases from 40 μm to at least 170 μm.

[0032] - The method may be such that: the laser engraving step includes using laser pulses.

[0033] - The duration of the laser pulse may be between 10 μs and 100 μs.

[0034] - When irradiating the lens element, the laser beam can be focused and has a spot area between 1250 μm² and 12500 μm². BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other advantages and features will become apparent after reading the description of the following drawings, wherein:

[0036] - Figure 1 is a plan view of a lens element according to an embodiment of the present disclosure;

[0037] - Figure 2 is a general contour view of a lens element according to an embodiment of the present disclosure;

[0038] - Figure 3 is a plan view of a lens element according to another embodiment of the present disclosure;

[0039] - Figure 4 is a simplified cross-sectional view of a blind hole according to the present disclosure;

[0040] - Figure 5 shows the relationship between the average visual score and the peak-to-valley size in graphical form;

[0041] - Figure 6 is a schematic diagram for explaining how to obtain the average visual score;

[0042] - Figure 7 and Figure 8 are views similar to Figure 2 showing different embodiments;

[0043] - Figure 9 is a view similar to Figure 1 showing another embodiment of the lens element of the present disclosure. DETAILED DESCRIPTION

[0044] In all the drawings, the same elements are labeled with the same reference numerals.

[0045] The following embodiments are only examples. Although the description relates to one or more embodiments, the present invention is not limited to these embodiments. Moreover, even if not explicitly mentioned, the features related to one embodiment can also relate to another embodiment. The simple features of different embodiments can also be combined to provide further implementations.

[0046] In this specification, the "front" or "rear" end face of a layer or lens element or surface is referenced with respect to the propagation of light through an ophthalmic lens towards the eye when an eyewear device carrying the ophthalmic lens is worn on a wearer's face. Thus, the "front" end face is always the end face that is furthest from the user's eye and thus closest to the field of view, and the "rear" end face is always the end face that is closest to the user's eye.

[0047] The terms "upstream" or "downstream" are used to describe the propagation of light from the outside, through a lens element, and towards the retina of a wearer's eye when the wearer is wearing the lens element. Thus, when light travels through its path towards the wearer's retina by first passing through a first object and then through a second object, the first object (surface, layer, imaging, etc.) is located upstream of the second object.

[0048] For example, when an image is located in front of the retina between the pupil and the retina, the image is located "upstream" or "in front of" the retina of the wearer's eye.

[0049] Conversely, when light travels through its path towards the wearer's retina by first passing through a second object and then through a first object, the first object is located "downstream" of the second object. Thus, the wearer's retina is located downstream of both the lens element and the wearer's pupil.

[0050] The present disclosure relates to a lens element for being worn in front of a wearer's eye.

[0051] In the context of the present disclosure, the term "lens element" can refer to a lens blank, an uncut optical lens, an ophthalmic optical lens suitable for fitting into a specific eyewear frame, or an ophthalmic lens.

[0052] As Figure 1 and Figure 2 shown, the lens element 10 according to the present disclosure includes a substrate 11 having a front end face 12F and a rear end face 12R.

[0053] As Figure 2 shown, the light incident on the ophthalmic article 1 is represented by an arrow 5, and the eye W represents the user / wearer of the lens element 1. Thus, the field of view 7 is on the side of the arrow 5, and the user "W" looks through the lens element 1 with his eye. The observer "O" is also located upstream of the lens element 1 and observes in the direction of the wearer "W". The wearer "W" is located downstream of the lens element 10.

[0054] The substrate 11 is made of, for example, a plastic material, such as a polymer substrate, such as a thermosetting material, in particular made of poly(urea - urethane), or a thermoplastic material, in particular made of polyamide (PA), such as nylon or polycarbonate, polyester, or TRIVEX (C)(Registered Trademark). Alternatively, a PET or TAC film or any other suitable material may be present on the substrate, on either surface of the substrate surface, for example, added by lamination. In Figure 1 and Figure 2 In the example of, the optical element 14 is located on the front end face 12F of the lens element 10. The optical elements 14 may be separated from each other on the front end face 12F.

[0055] In an alternative embodiment (not shown), the optical element 14 may be located on the rear end face 12R, or on both end faces, that is, on both the front end face 12F and the rear end face 12R. In the above example where the film material is present on the substrate 11, the optical element 14 may be located on the film material.

[0056] The region in the front end face 12F other than the region formed by the plurality of optical elements 14 is designated as the refractive region 16. In other words, the refractive region 16 is the complementary region of the region occupied by the plurality of optical elements 14.

[0057] The refractive region 16 is configured to: provide a first optical power for the wearer under standard wearing conditions (especially for macular vision) based on a prescription for correcting the abnormal refractive state of the wearer's eye. The goal of the refractive region 16 is to focus the incident parallel light on the retina.

[0058] The wearing conditions should be understood as the position of the lens element 10 relative to the wearer's eye, for example, defined by the tilt angle, the distance from the cornea to the lens, the distance from the pupil to the cornea, the distance from the center of rotation of the eye (CRE) to the pupil, the distance from the CRE to the lens, and the wrap angle.

[0059] As can be seen in Figure 2 the optical element 14 is also implemented as a blind hole (also labeled "14").

[0060] Such blind holes 14 can be manufactured in a variety of ways, especially by laser ablation, but also by mechanical drilling, or impact, or etching, or stamping, or molding using a specific mold with a specific protrusion, or by 3D printing a surface with holes, or any other relevant technology.

[0061] The lens element 10 further includes an unengraved circular central region 16C, which is entirely part of the refractive region 16 and is designed to be located in front of the wearer's pupil when worn. This unengraved circular central region 16C is also referred to as COCA (circle of clear aperture). The blind holes 14 may surround the unengraved circular central region 16C.

[0062] For example, the diameter of the unengraved circular central region 16C is 3.5 mm.

[0063] In this example, the blind holes 14 are arranged in a concentric ring around the circular central region 16C.

[0064] Figure 3 Another configuration is shown. Figure 3 With Figure 1 similar, and shows a top view of the lens element 10. According to this embodiment, the blind holes are arranged in a randomized square array. Arrow A points to an enlarged / magnified view of the blind hole.

[0065] According to this embodiment, the diameter of the blind holes 14 is particularly in the range between 170 μm and 220 μm.

[0066] For example, the distance between the centers of two adjacent blind holes 14 is between 300 μm and 420 μm.

[0067] Other configurations, such as a hexagonal pattern or a randomized circular array, can also be considered.

[0068] The optical element implemented as the blind hole 14 in the present disclosure is used to generate unfocused light, for example, in front of the retina, so as to reduce the contrast to slow down the progression of myopia. The blind hole 14 has a scattering effect on the light beam incident on the wearer's retina, thus contributing to controlling the progression of myopia.

[0069] Now turning to Figure 4 , which shows a simplified cross-sectional view of the blind hole 14 according to the present disclosure.

[0070] The blind hole 14 has a generally circular shape (see Figure 1 ), having straight sidewalls 14S, a surrounding boundary 14B (which may protrude relative to the refractive region 16), and a termination end 17. The straight sidewalls 14S extend from the boundary 14B to the termination end 17 of the blind hole 14. The straight sidewalls 14S may be inclined or parallel to the longitudinal axis of the blind hole 14. The termination end 17 is recessed relative to the boundary 14B and relative to the refractive region 16, for example, recessed relative to the surface defining the refractive region 16.

[0071] Figure 4 Parameters PV (peak-to-valley size) and parameter BP (boundary protrusion) are also defined. Parameter PV is the depth of the blind hole 14 relative to the height of the boundary 14B. Parameter BP is the protrusion height of the boundary 14B relative to the refractive region 16.

[0072] The inventors have found that an optical element 14 with a peak-to-valley size PV equal to or less than 25 μm, in particular equal to or less than 15 μm, allows obtaining such a lens element 10 that reduces the white foggy visual perception seen from the observer's viewing point while still having a positive effect on myopia control.

[0073] The peak-to-valley size PV of such an optical element 14 can be at least 3 μm, preferably at least 4 μm, to provide effective myopia control.

[0074] Figure 5 The results of a study are shown, in which lens elements with different PV values were manufactured and evaluated. Figure 5 is a graph showing the relationship between the peak-to-valley size PV of the lens element and the average visual score, which was obtained using the procedure described below.

[0075] The linear regression line 100 shows the relationship between the average visual score and the value of the parameter PV of the lens element when the substrate is made of polycarbonate material.

[0076] The linear regression line 102 shows the relationship between the average visual score and the value of the parameter PV of the lens element when the substrate is made of TRIVEX (C) (registered trademark) material.

[0077] In both cases, smaller PV values result in better average visual scores.

[0078] To obtain the average visual score, a test protocol was defined.

[0079] Under specific lighting conditions, it was examined by two independent observers using CIE standards (with a D65 light source), where there was no ceiling lighting and the examination was carried out in a room with light-blocking curtains.

[0080] Two criteria (described later) were analyzed in two different backgrounds: one background was black, and one background was the Caucasian mannequin M, as Figure 6 shown.

[0081] The black background provides a higher-contrast environment for observing the lens element, which is more likely to yield discriminatory results. On the other hand, the mannequin M provides a more realistic environment to simulate the situation where another person is observing the wearer.

[0082] The observers evaluated the following two criteria: => Visibility of the engraving of the optical element / blind hole 14 => Visibility of the COCA (clear aperture circle), where the COCA corresponds to the unengraved circular central region 16C.

[0083] The observer used a continuous scale ranging from 1 to 5, where 1 corresponded to the least apparent and 5 corresponded to the most apparent.

[0084] Thus, a low visual rating indicates a reduction in the white fogginess perceived by the observer on the lens element 10 when the observer is observing the wearer of the lens element 10.

[0085] The lower the visibility of the COCA, the better the performance of the lens element 10 is considered.

[0086] The optical element / blind hole 14 is located within an annular region, the inner circular boundary of which forms the COCA 16C, and the outer circular boundary of which may be the edge of the lens element or a smaller shape within the lens element. The annular region may be non-circular. The lower the visibility of the engraved optical element / blind hole 14, the better the performance of the lens element 10 is considered. It should be reminded that the "performance" mentioned here is considered to be the aesthetic performance rather than the performance of the blind hole in controlling myopia.

[0087] From Figure 5 it can be clearly concluded that the peak-to-valley size has a significant effect on the average visual rating.

[0088] In addition, it was observed that when the blind hole 14 protruded less than 5 μm (BP < 5 μm) relative to the surrounding end face surface forming the refractive region 16, the performance of the lens element was further improved from the observer's perspective. In particular, the optical element / blind hole 14 was less apparent to the observer.

[0089] In addition, when the end face of the lens element 10 (the front end face 12F in this example) is located within the region defined by the optical element 14, and this region has an annular region around the COCA (for example, as Figure 1 shown) and has a power spectral density (PSD) of 10 10 nm⁻³ (±10%) in the spectral spatial band from 10 mm⁻¹ to 80 mm⁻¹, a "fading" effect of the visibility of the blind hole 14 and the COCA 16C was observed, which means a reduction in the visibility of the blind hole 14 and the COCA, and the lens element obtained a lower average visual rating.

[0090] Surface height measurements were acquired by an optical interferometer to optically measure the power spectral density (PSD).

[0091] The calculation of the power spectral density (PSD) from the height map was implemented according to the following article: "AZOUIGUI, S., SILVESTRI, Z., ZERROUKI, C., BOUHTIYYA, S., PLIMMER, M.D., SPALTMANN, D., KOVALEV, A., WOYDT, M. and PINOT, P., "Angle resolved scattering as a tribological investigation tool for surface characterization", Wear, Volumes 326-327, Pages 58-67, March 2015, DOI 10.1016 / j.wear.2014.12.040".

[0092] The power spectral density (PSD) is calculated in an area containing a plurality of blind holes 14. Typically, the PSD can be determined in a square area of 4 mm × 4 mm (corresponding to approximately sixty blind holes 14 in the research sample).

[0093] This document discloses a method for manufacturing a lens element. As described above, the blind holes 14 can be made particularly by laser ablation.

[0094] Laser ablation includes a laser engraving step using a laser having an engraving wavelength equal to or less than 355 nm, particularly 355 nm or 266 nm.

[0095] The laser engraving step includes using laser pulses. For example, the duration of the pulses is between 10 µs and 100 µs.

[0096] Laser light with a shorter wavelength has higher ablation energy compared to longer wavelengths. Thus, for example, at a laser wavelength of 266 nm, the pulse duration is 30 µs, while for a laser wavelength of 355 nm, the pulse duration can be approximately 85 µs.

[0097] For laser engraving, the laser beam is focused when irradiating the lens element 10 and has a spot area between 1250 µm² and 12500 µm².

[0098] Figure 7 Shows a further improvement of the lens element 10, which is Figure 2 different in that the lens element 10 includes a hard coating 18 provided on a substrate 11.

[0099] An example of the hard coating 18 is polysiloxane, for example, it is a single layer or multiple layers, and the thickness is between 2.5 and 4.5 μm.

[0100] In laser ablation, the blind hole 14 is drilled through the hard coating 18 and into the substrate 11 until a certain depth is reached. The peak-to-valley value PV of the blind hole 14 takes into account the thickness of the hard coating 18.

[0101] For facilitating laser ablation of blind hole laser drilling, the hard coating 18 has a refractive index of 1.6 ± 2%.

[0102] Enhancement of laser absorption can be achieved when the hard coating includes a compound that enhances laser absorption between 250 nm and 370 nm. For example, such compounds that enhance laser absorption include metal oxides or metal-containing colloids. For example, colloids of zirconium or tantalum, colloids of titanium or tin can be mentioned, where the absorbability of the colloids of zirconium or tantalum is lower than that of the colloids of titanium, or even lower than that of the colloids of tin. In other words, when using colloids of tin or titanium, a more aesthetically appealing product is obtained.

[0103] In addition, another parameter of the hard coating 18 for enhancing engraving and obtaining an improved average visual score is the extinction coefficient k. In the wavelength range between 250 - 355 nm, the extinction coefficient k > 0.005. Preferably, in the wavelength range between 260 - 355 nm, 0.05 < k < 0.5.

[0104] In addition, when the substrate exhibits non-zero absorption in the wavelength range of 250 - 355 nm (corresponding to the ablation wavelength of the laser) to achieve zero transmission, enhancement of engraving and improvement of the average visual score are achieved. For example, examples of substrates containing absorption compounds, such as 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, which is used as an ultraviolet absorber. This compound absorbs ultraviolet light between 340 - 355 nm depending on the specific composition and is compatible with almost all synthetic resins.

[0105] By using a laser with a wavelength close to 266 nm, better performance can be obtained because most organic materials that are transparent in the visible light range will absorb light near 266 nm even without additional compounds. In addition, the absorption is directly done by the material of the polymer matrix rather than within the compound. Therefore, it is considered to be helpful for controlling the marking.

[0106] According to Figure 8 As shown in the further development, an anti-reflection coating 20 is interposed between the substrate 11 and the hard coating 18, which also helps to enhance engraving and obtain an improved average visual score.

[0107] Laser ablation results in a blind hole being drilled through the hard coat 18, the anti-reflection coat 20, and partially into the substrate 11. In Figure 8 this figure, as in the other figures, the size of the blind hole 14 is exaggerated for purposes of illustration.

[0108] The lens element 10 according to the present disclosure and according to all different embodiments exhibits a haze level of 15% ± 5% in transmission, as defined in standard ASTM D-1003.

[0109] According to Figure 9 another embodiment shown, the unengraved circular central region 16C is surrounded by an annular region 16AZ within which the diameter of the blind holes 14 gradually increases from a first diameter (e.g., 40 μm) to a second diameter (e.g., at least 170 μm). As indicated by the arrow, the width of the annular region 16AZ, which can be considered a "transition zone", can be, for example, 1.5 mm. This feature particularly helps to make the COCA 16C less noticeable.

Claims

1. A lens element (10) for being worn in front of a wearer's eyes, the lens element comprising: A substrate (11) having a front end face (12F) and a rear end face (12R); and an optical element (14) located on one of the front end face (12F) or the rear end face (12R) of the lens element (10), the optical element (14) being realized in the form of a blind hole with respect to the end face surface and reducing the contrast on the retina of the wearer, thereby contributing to the control of myopia, wherein at least one optical element (10) has a peak-to-valley size (PV) equal to or less than 25 μm.

2. The lens element according to claim 1, wherein the optical element (14) is a blind hole realized by laser ablation.

3. The lens element according to claim 2, further comprising an anti-reflection coating (20).

4. The lens element according to any one of claims 1 to 3, further comprising a hard coating (18) having a refractive index of 1.6 ± 2%.

5. The lens element according to claim 4, wherein the hard coating (18) comprises a compound for enhancing laser absorption between 250 nm and 370 nm.

6. The lens element according to claim 5, wherein the compound for enhancing laser absorption comprises a metal oxide or a metal-containing colloid.

7. The lens element according to any one of claims 1 to 6, wherein the end face (12F) of the lens element (10) is present in a zone and is delimited by the optical element (14), showing a power spectral density of 10 10 nm⁻³ ± 10%.

8. The lens element according to any one of claims 1 to 7, wherein the boundary of at least one blind hole (14) protrudes less than 5 μm from the surrounding end face surface (16), thereby presenting the optical element (14).

9. The lens element according to any one of claims 1 to 8, wherein the optical element (14) has a peak-to-valley size equal to or less than 15 μm.

10. The lens element according to any of the preceding claims in combination with claim 2, wherein the substrate has a transmittance of less than or equal to 1%, preferably less than or equal to 0.1%, and more preferably less than or equal to 0.01% for a 2 mm layer at the ablation wavelength of the laser.

11. The lens element according to any of the foregoing claims in combination with claims 4, 5 or 6, wherein the hard coating has an extinction coefficient (k) higher than 0.005, preferably higher than 0.05, in the wavelength range of 250 - 355 nm.

12. A method of manufacturing a lens element (10) for wearing in front of a wearer's eyes, the lens element comprising: A substrate (11) having a front end face (12F) and a rear end face (12R); and an optical element (14) located on one of the front end face (12F) or the rear end face (12R) of the lens element (10), the optical element (14) being realized in the form of a blind hole with respect to the end face surface and reducing the contrast on the retina of the wearer, thereby contributing to the control of myopia, wherein at least one optical element (10) has a peak-to-valley size (PV) equal to or less than 25 μm, the method comprising a laser engraving step using a laser, the engraving wavelength of the laser being equal to or less than 355 nm, particularly 355 nm or 266 nm.

13. The method according to claim 12, wherein the laser engraving step comprises using laser pulses.

14. The method according to claim 12 or 13, wherein the duration of the laser pulse is between 10 μs and 100 μs.

15. The method according to any one of claims 12 to 14, wherein when irradiating the lens element, the laser beam is focused and has a spot area between 1250 μm² and 12500 μm².

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