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EP-4368381-B1 - METHOD FOR MANUFACTURING AN OPHTHALMIC ARTICLE HAVING AT LEAST ONE MICROSTRUCTURED SURFACE, AND OPHTHALMIC ARTICLE THUS OBTAINED

EP4368381B1EP 4368381 B1EP4368381 B1EP 4368381B1EP-4368381-B1

Inventors

  • BIVER, CLAUDINE
  • CANO, JEAN-PAUL

Dates

Publication Date
20260513
Application Date
20221109

Claims (15)

  1. Method for manufacturing an ophthalmic article having a front main surface and a rear main surface, at least one of which is a microstructured surface, the method comprising the following steps: a) Providing an ophthalmic substrate (10) with a substrate surface which is either hydrophobic or hydrophilic; b) Patterning the substrate surface to create thereon a surface wettability pattern comprising a two-dimensional array (3) of mutually distant hydrophilic micro-areas (1) and of at least one hydrophobic zone (2) which separates the hydrophilic micro-areas (1) from each other; c) Coating the two-dimensional array (3) with a hydrophilic liquid which is able to form an abrasion-resistant coating in a dried and/or cured state, to form mutually distant droplets (D) of the hydrophilic liquid which are anchored to the hydrophilic micro-areas (1) by wettability thereof; and d) Drying and/or curing the mutually distant droplets (D) of the hydrophilic liquid, to generate therefrom a three-dimensional array of micro-lenses forming the at least one microstructured surface.
  2. Method according to claim 1, wherein step a) comprises rendering the ophthalmic substrate (10), which consists of a mineral material, either hydrophobic or hydrophilic on said substrate surface.
  3. Method according to claim 1, wherein step a) comprises providing the ophthalmic substrate (10), which consists of an organic material, with a first abrasion-resistant coating which is either hydrophobic or hydrophilic and defines said substrate surface, and wherein preferably in step c) the hydrophilic liquid is selected so that the abrasion-resistant coating forming the micro-lenses, or second abrasion-resistant coating, has a Bayer value greater than or equal to the Bayer value of the first abrasion-resistant coating, both Bayer values being measured in accordance with the ASTM F735-81 standard and being preferably greater than or equal to 2.
  4. Method according to any of preceding claims, wherein in step c) the hydrophilic liquid is a polar liquid selected from solutions in a polar solvent and emulsions comprising a polar phase.
  5. Method according to claim 4, wherein in step c) the hydrophilic liquid comprises at least one inorganic oxide of a metal or non-metal selected from colloidal silica, titania, zirconia, antimony oxide and mixtures thereof, and wherein the hydrophilic liquid is selected from polar solutions comprising alcoholic, ketones and/or ester solvents, the hydrophilic liquid comprising an epoxysilane hydrolyzate, the at least one inorganic oxide and a catalytic amount of an aluminum-based curing catalyst.
  6. Method according to any of preceding claims, wherein step c) is implemented by dip coating, by dipping the ophthalmic substrate (10) provided with the substrate surface once patterned into a bath of the hydrophilic liquid and afterwards by a controlled withdrawal of the dipped ophthalmic substrate (10) from the bath, the withdrawal being controlled so as to obtain a desired curvature radius and/or volume for each of the micro-lenses obtained in step d).
  7. Method according to claim 6, wherein in the dip coating of step c), a maximum allowable withdrawal speed is determined, by measuring a critical transition speed where no film of the hydrophilic liquid is dragged onto the at least one hydrophobic zone (2) once dipped and withdrawn, and wherein the controlled withdrawal of the dipped ophthalmic substrate (10) from the bath is implemented at an adjusted withdrawal speed selected to be lower than or equal to said critical transition speed.
  8. Method according to claim 6 or 7, wherein steps b) and c) are implemented so that the micro-lenses obtained in step d) have at least one greater transverse direction, such as a diameter, which is greater than 500 µm and preferably of between 1 mm and 2 mm in case the micro-lenses are designed for controlling evolution of myopia when the ophthalmic article is an ophthalmic curved prescription lens.
  9. Method according to any of preceding claims, wherein • the ophthalmic substrate (10) consists of a mineral material, or of an organic material which is thermosetting, photocurable or thermoplastic; and wherein • the method further comprises at least one of steps A) and B): A) coating the ophthalmic substrate (10) before step a) with a primer coating which is itself provided with said substrate surface, and B) laminating the ophthalmic substrate provided with the patterned substrate surface on an existing curved lens, by a forming technique implemented by laminating - between step b) and step c), the ophthalmic substrate (10). provided with said substrate surface patterned according to the surface wettability pattern. (3), or - after step d), the ophthalmic substrate (10) provided with the patterned substrate surface and the three-dimensional array of micro-lenses.
  10. Method according to any of preceding claims, wherein the method further comprises the following steps: e) removing the three-dimensional array of micro-lenses obtained in step d) by dipping in a removing bath and optionally providing said substrate surface with protective masking means, so as to selectively recover the ophthalmic substrate (10) provided with the substrate surface, and f) implementing the sequence of steps b), c) and d) at least once, to obtain another three-dimensional array of micro-lenses forming the at least one microstructured surface.
  11. Method according to any of preceding claims, wherein step a) is implemented by using, by way of the ophthalmic substrate (10) provided with said substrate surface, an ophthalmic lens selected from a finished ophthalmic lens and an ophthalmic lens blank optionally edged, preferably an ophthalmic curved prescription lens.
  12. Method according to any of preceding claims, wherein step b) is implemented by a mask-assisted or maskless technique selected from chemical etching, laser ablation or etching, low pressure or atmospheric plasma or corona etching, UV or ozone etching, Reactive Ion Etching (RIE) and chemical grafting of molecules bearing hydrophilic or hydrophobic functions, to create the hydrophilic micro-areas (1) and the at least one hydrophobic zone (2) on said substrate surface.
  13. Method according to claim 12, wherein step b) is implemented by a mask-assisted technique by (i) patterning said substrate surface which is selected to be hydrophobic, preferably by a chemical etching technique assisted with a flexible mask (20) applied under pressure onto the substrate surface, or by (ii) beforehand providing in step a) the substrate surface with an outer surface which is either already hydrophilic or is rendered hydrophilic between steps a) and b), and creating in step b) the at least one hydrophobic zone (2) via said mask-assisted technique by treating unmasked areas with said molecules bearing hydrophobic functions.
  14. Method according to claim 13, wherein step a) comprises providing the ophthalmic substrate (10), which consists of an organic material, with a first abrasion-resistant coating which is hydrophobic and defines said substrate surface, wherein step b) is implemented in case (i) by providing the flexible mask (20) with an array of through micro-holes optionally having different shapes and/or dimensions, the through micro-holes preferably having a diameter of between 1 mm and 2 mm, and by immersing the first abrasion-resistant coating in a caustic bath of NaOH or KOH, and wherein in case (ii), the outer surface of the first abrasion-resistant coating is rendered hydrophilic between steps a) and b) by: - at least one of chemical etching, laser ablation or etching, low pressure or atmospheric plasma or corona etching, UV or ozone etching and Reactive Ion Etching (RIE), and chemical grafting of molecules bearing hydrophilic functions, or by - depositing onto the first abrasion-resistant coating a hydrophilic layer comprising at least one inorganic oxide of a metal or non-metal selected from silica, titania, zirconia, antimony oxide and mixtures thereof.
  15. Ophthalmic article obtained by a method according to any of claims 1-14, wherein the ophthalmic article has a front main surface and a rear main surface, at least one of which is a microstructured surface, and comprises: - an ophthalmic substrate (10) provided with a patterned substrate surface which is patterned according to a surface wettability pattern (3) comprising mutually distant hydrophilic micro-areas (1) and of at least one hydrophobic zone (2) which separates the hydrophilic micro-areas (1) from each other, and - a three-dimensional array of micro-lenses which form the at least one microstructured surface and are respectively anchored to the sole hydrophilic micro-areas (1), the micro-lenses being based on an abrasion-resistant coating which coats the patterned substrate surface, and in case the ophthalmic substrate (10) consists of an organic material, said substrate surface is defined by a first abrasion-resistant coating which is patterned according to said surface wettability pattern (3), said abrasion-resistant coating being a second abrasion-resistant coating which coats the patterned first abrasion-resistant coating and which preferably has a Bayer value greater than or equal to the Bayer value of the first abrasion-resistant coating, both Bayer values being measured in accordance with the ASTM F735-81 standard.

Description

FIELD OF THE INVENTION The present invention relates to a method for manufacturing an ophthalmic article having at least one microstructured surface, and to an ophthalmic article obtained by this method. The invention particularly applies to an ophthalmic lens comprising a three-dimensional array of micro-lenses configured to control evolution of myopia when the ophthalmic article is an ophthalmic curved prescription lens, even though the ophthalmic article may alternatively be incorporated into a smart eyewear device. DESCRIPTION OF RELATED ART Ophthalmic articles such as lenses generally comprise a base-lens substrate which is shaped in order to provide a desired optical power, and an abrasion-resistant coating (also known as anti-abrasion or hard coating) covering at least one surface of the base-lens substrate to prevent the latter from being damaged by scratches. For a number of applications, it has been found desirable to provide on the base-lens substrate a plurality of micro-lenses, providing a local change of the power of the optical article. For instance, it is known from US 2017/0131567 A1 a lens comprising a plurality of microlenses formed on a surface of the lens, the local change of power provided by the micro-lenses enabling to slow down the progress of myopia. Micro-lenses arrays are thus used for adding defocusing effect on a periphery of an ophthalmic corrective lens to control the evolution of myopia on kids. Indeed, some ophthalmic lenses are today specially designed and manufactured for that purpose. Nonetheless, this approach limits the extension of this technology to some materials, and the specific manufacturing process - which typically involves molds - induces extra costs and investments. Existing molding processes of micro-lenses indeed require to protect the delicate microlenses surface with another covering material, and involve the conception and manufacturing of expensive and delicate molds. Specifically, such known processes typically inject a thermoplastic or thermosetting resin into a master mold containing a surface replication of the micro-lens array in an inverted profile. To protect the micro-lens array and guaranty a prolonged ophthalmic effect for the ophthalmic article, the molded micro-lenses are covered in a subsequent manufacturing step with the above-mentioned covering material, which results in that the focal lens defined by the micro-lens array is corrected due to the refractive index of the specific covering material. Further, this subsequent step is particularly delicate to control. Apart from the fact that known molding. manufacturing processes of prescription ophthalmic lenses are complex and costly, another drawback of these processes is that they are not versatile and limit the range of the molded ophthalmic articles that may be obtained, inasmuch as such processes cannot be easily implemented for all ophthalmic lens materials. WO 2020/078964 A1 relates to an optical article comprising a base lens substrate, having a front surface and a back surface,an abrasion resistant coating covering at least one of said front surface and said back surface, the abrasion resistant coating having a first surface at the interface with the base lens substrate and a second surface opposite the first, andat least one optical element protruding from one of the first and second surfaces of said abrasion resistant coating, said optical element being composed of a material adapted to form an abrasion resistant coating and which may be formed of the same abrasion resistant coating by additive manufacturing, photolithography, thermal embossing or injection molding. The article of Daniel M. Hartmann, Osman Kibar, and Sadik C. Esener, Characterization of a polymer microlens fabricated by use of the hydrophobic effect, July 1, 2000 / Vol. 25, No. 13 / OPTICS LETTERS 975, relates to means of fabricating hydrophilic domains in a hydrophobic background by lithographically patterning an adhesive hydrophobic layer. Polymer micro-lenses were fabricated by use of a dip-coating technique on a variety of mineral substrates (SiO2, SiN, Ga As, InP, etc.), ranging in size from 2 µm to 500 µm in diameter. It is to be noted that this article concerns optical systems in optics-based applications, but does not disclose an ophthalmic article, such as an ophthalmic lens or an eyewear article. WO 2021/209527 A1 discloses a method for manufacturing an ophthalmic article having a front main surface and a rear main surface, at least one of which is a microstructured surface. SUMMARY OF THE INVENTION An object of the invention is to overcome at least the above-mentioned drawbacks, by providing a method for manufacturing an ophthalmic article having a front main surface and a rear main surface, at least one of which is a microstructured surface, by a simple additive process allowing to provide existing ophthalmic article of any material and geometry, such as curved prescription lenses, with an array of mic