HK40043177B - Apparatus and methods for molding rigid ocular lenses - Google Patents

Description

Equipment and methods for molding rigid eyepieces

Background Technology

Contact lenses are a subset of ocular lenses, which are thin lenses placed directly on the surface of the eye. Ocular lenses are broadly classified into two types: soft eyepieces and rigid or kinetic eyepieces. Soft eyepieces are made of flexible and deformable materials (sometimes hydrogel) and can deform to conform to the shape of the eye's surface during use. Conversely, rigid, gas-permeable eyepieces typically do not deform when placed on the eye, but in some cases (e.g., in the case of orthokeratology lenses), they can cause the eye's surface to conform to the shape of the lens itself. Therefore, rigid lenses require higher tolerances and manufacturing precision compared to soft eyepieces.

Initially, rigid gas-permeable eyepieces were made of rigid polymers (such as poly(methyl methacrylate) (PMMA)). However, these rigid polymers were not sufficiently breathable and did not allow ambient oxygen to pass through the lens to the surface of the eye, thus imposing many limitations on the user. More recently, rigid lenses are made of oxygen-permeable materials, allowing for greater comfort and longer wear times. In some cases, the wearing time is as long as or longer than that of soft contact lenses. These oxygen-permeable rigid lenses are commonly referred to as rigid gas-permeable lenses or RGP lenses.

RGP lenses are manufactured by turning or lathe cutting. This process involves attaching lens material in the form of workpiece buttons to a rotating mount, and then removing excess material to form the desired surface geometry. The turning process, along with extensive post-turning honing and polishing, enables the tolerances and precision required for comfortable RGP lenses, especially those that reshape the eye and demand extremely high tolerances, such as orthokeratology lenses. However, turning generates excess waste when removing material to form the lens. Turning on a per-lens basis is also slow and expensive, as each eyepiece must be turned individually. Furthermore, turning can lead to inconsistencies between lenses and is limited to rotationally symmetric geometries.

On the other hand, soft contact lenses are typically manufactured using casting processes, such as casting molding or spin casting. These processes are relatively inexpensive, fast, repeatable, and can produce large quantities of lenses with fewer defects. Through these casting processes, molds are formed to create the desired lens shape, and then liquid monomers are cast into these molds to create lenses with the desired shape and profile. However, compared to RGP lenses, soft contact lenses have much looser manufacturing tolerances because once hydrated, they become flexible and conform to the user's eye surface, thus minimizing the impact of most molding defects.

Therefore, there is a need for a fast, efficient, reliable, and inexpensive method to manufacture rigid, breathable eyepieces.

Summary of the Invention

According to some embodiments, a rigid breathable eyepiece can be formed by a process comprising: forming at least a portion of a mold including a first side having a profile shaped to form a front surface of the rigid breathable eyepiece; applying a liquid lens material to the first side of the portion of the mold; and at least partially solidifying the liquid lens material to form the rigid breathable eyepiece, wherein at least one surface of the rigid breathable eyepiece has a _Ra roughness of less than about 5 nanometers.

In some embodiments, the process further includes casting the liquid lens material to form the rigid, breathable eyepiece.

In some embodiments, the portion of the mold does not need to be polished before forming the rigid, breathable eyepiece.

In some embodiments, causing the liquid lens material to solidify at least partially includes exposing the liquid lens material to photochemical radiation.

In some embodiments, the at least portion of a mold including the first side, the first side having a contour shaped to form the front surface of the rigid, ventilated eyepiece, is formed by: machining a tooling blank to form a convex injection mold tooling having a surface corresponding to the front surface of the eyepiece; and using the convex injection mold tooling to injection mold the portion of the mold to form the portion of the mold including the first side, the first side having a contour shaped to form the front surface of the rigid, ventilated eyepiece.

In some embodiments, machining the blank includes using a lathe with a positioning resolution of less than about 10 nanometers.

In some embodiments, machining the blank includes using a multi-axis milling machine with a positioning resolution of less than about 10 nanometers.

In some embodiments, the rigid ventilated eyepiece includes a rigid ventilated eyepiece.

In some embodiments, the rigid gas-permeable eyepiece is a corneal corrective lens.

In some embodiments, the radius of curvature of the back optic zone of the rigid, breathable eyepiece has a dimensional tolerance equal to or less than about 0.05 mm.

In some embodiments, the rigid, breathable eyepiece deforms the surface of the user's eye.

In some embodiments, a method of forming a rigid, breathable eyepiece includes: forming at least a portion of a mold including a first side having a profile shaped to form a front surface of the rigid, breathable eyepiece; applying a liquid lens material to the first side of the portion of the mold; and at least partially solidifying the liquid lens material to form the rigid, breathable eyepiece.

In some embodiments, at least one surface of the rigid, breathable eyepiece has a _Ra roughness of less than about 5 nanometers.

In some embodiments, the method further includes casting the rigid, breathable eyepiece.

In some embodiments, at least a portion of the mold does not need to be polished before forming the rigid breathable eyepiece to produce the rigid breathable eyepiece having a _Ra roughness of less than about 5 nanometers.

In some embodiments, solidifying the liquid lens material at least partially includes exposing the liquid lens material to photochemical radiation.

In some embodiments, forming the at least a portion of the mold includes: providing mold material; processing a blank to form a convex injection mold tooling having a surface corresponding to the front surface of the eyepiece; and using the convex injection mold tooling to injection mold the portion of the mold to form the portion of the mold including a first side having a profile shaped to form the front surface of the rigid, breathable eyepiece.

In some embodiments, machining the blank includes using a multi-axis milling machine with a positioning resolution of less than about 10 nanometers.

In some embodiments, the rigid gas-permeable eyepiece is a corneal corrective lens.

In some embodiments, the radius of curvature of the rear-viewing area of the rigid, breathable eyepiece has a dimensional tolerance equal to or less than about 0.005 mm.

In some embodiments, the rigid, breathable eyepiece is configured to deform the surface of the user's eye.

In some embodiments, the liquid lens material is an isotropic material having a viscosity greater than 5000 cps (centipoise) at 20°C, and the rigid, breathable eyepiece has a modulus greater than 500 MPa.

A method of forming a rigid, breathable eyepiece includes: providing a mold including a first side having a profile shaped to form a front surface of the rigid, breathable eyepiece; dispensing a liquid lens material to the first side of the portion of the mold, the liquid lens material comprising an isotropic material having a viscosity greater than 5000 cps at 20°C; and at least partially solidifying the liquid lens material to form the rigid, breathable eyepiece, wherein the rigid, breathable eyepiece has a modulus greater than 500 MPa.

In some embodiments, the rigid gas-permeable eyepiece is a corneal corrective lens.

In some embodiments, the rigid cast vented eyepiece comprises casting the rigid vented eyepiece.

The molded rigid gas-permeable eyepiece includes a molded lens body, the molded lens body including a front surface and a rear surface, wherein the rigid gas-permeable eyepiece has a modulus greater than 500 MPa and a D_{_K} greater than 100.

In some embodiments, the molded rigid gas-permeable eyepiece is a corneal corrective lens.

In some embodiments, the molded rigid breathable eyepiece includes a viewing area, a reversing area, an alignment area, and a peripheral area formed on the front surface of the molded lens body.

In some embodiments, the lens is cast.

In some embodiments, the lens body has a varying thickness from approximately 10 μm to more than 80 μm.

In some embodiments, the lens is configured to be attached to the cornea and defines an apical clearance between the anterior surface and the cornea between 5 μm and 40 μm.

The above-described invention provides a simplified introduction to a series of concepts, which will be further described later in the detailed description. The above-described invention and background information are not intended to identify key concepts or essential aspects of the disclosed subject matter, nor should they be used to constrain or limit the scope of the claims. For example, the scope of the claims should not be limited based on whether the enumerated subject matter includes any or all of the aspects described in the above-described invention and/or solves any of the problems mentioned in the background information.

Attached Figure Description

The accompanying drawings illustrate various embodiments of the principles described herein and are part of this specification. The embodiments shown are merely examples and do not limit the scope of the claims.

Figure 1A is a cross-sectional view of an embodiment of a rigid, breathable eyepiece formed according to the principle of the present invention.

Figure 1B is a cross-sectional view of an embodiment of a rigid, breathable corneal corrective lens disposed on the eye according to the principles of the present invention.

Figures 2A to 2C are cross-sectional views of a method for forming a mold for casting a rigid eyepiece according to the principles of the present invention.

Figure 3 is a cross-sectional view of an embodiment of a casting molding system for forming an eyepiece according to the principles of the present invention.

Figure 4 is a cross-sectional view of an embodiment of a casting molding system for forming an eyepiece according to the principles of the present invention.

Figure 5 is a flowchart illustrating a method for forming a die portion of a mold assembly according to the principles of the present invention, the mold assembly being used to mold a rigid, breathable eyepiece.

Figure 6 is a flowchart illustrating a method for forming a punch portion of a mold assembly according to the principles of the present invention, the mold assembly being used to mold a rigid, breathable eyepiece.

Figure 7 is a flowchart illustrating an exemplary method for casting a rigid, breathable eyepiece according to the principles of the present invention.

Figure 8 is a cross-sectional view of the interface between the user's cornea and the molded rigid gas-permeable eyepiece according to the principle of the present invention.

Figure 9 is a cross-sectional view of a rigid, breathable eyepiece formed as a stacked array according to the principle of the present invention.

Figure 10 is a top view of a molded rigid gas-permeable scleral lens according to the principle of the present invention.

Throughout the accompanying drawings, the same reference numerals indicate similar but not necessarily identical elements.

Detailed Implementation

Rigid, breathable eyepieces (especially contact lenses) require a high degree of precision during their manufacture to achieve desired dimensional tolerances and surface smoothness. The principles described herein encompass rigid, breathable eyepieces formed from a mold through a casting process. In one example, this casting process is a casting molding process. The principles described herein also include methods for manufacturing such molds and associated components, for example, by casting molding, spin casting, or other molding methods.

Figure 1A is a cross-sectional view of one embodiment of a rigid eyepiece 10 (e.g., a rigid gas-permeable eyepiece) formed according to the process described herein. In some embodiments, the rigid gas-permeable eyepiece may include a viewing zone 20 configured to focus light passing through the viewing zone onto the user's retina. The viewing zone 20 is positioned in front of the pupil of the eye. Typically, a non-viewing zone 12 circumscribes the viewing zone 20 and constitutes the remainder of the eyepiece 10. This non-viewing zone 12 may be positioned on the iris, and in some cases on portions of the conjunctiva and sclera of the eye. In some embodiments, the rigid gas-permeable eyepiece is formed according to the methods and processes described herein and can be used for corneal reshaping. Typically, in orthokeratology lenses, rigid contact lenses engage only with the cornea. In some embodiments, the rigid gas-permeable eyepiece may not deform substantially when placed on the eye, while in some cases (e.g., in the case of orthokeratology lenses) it may deform the surface or contour of the eye to conform to the shape of the lens itself and may be positioned only on the cornea of the eye.

The rigid, ventilated eyepiece 10 may have a rear surface or back surface 22 and a front surface or front surface 24. The shape of the back surface 22 of the viewing area 20 can be described by the radius of curvature or any number of non-rotationally symmetric geometries. In some embodiments, the rigid, ventilated eyepiece 10 has a thickness of approximately 0.01 mm to approximately 0.14 mm. The thickness of the eyepiece 10 may vary at different locations. For example, the eyepiece 10 may be thicker or thinner near the outer edge of the eyepiece 10 compared to the central region of the lens.

Rigid gas-permeable eyepieces formed according to the methods and processes described herein can be made from any material suitable for use in rigid contact lenses. In some embodiments, a rigid gas-permeable eyepiece is a rigid gas-permeable eyepiece, and therefore, the rigid gas-permeable eyepiece can be formed from a gas-permeable or oxygen-permeable material. In some embodiments, a rigid gas-permeable eyepiece can include a polymer material. For example, in some embodiments, a rigid gas-permeable eyepiece can include a siloxane material. In some embodiments, a rigid gas-permeable eyepiece can include an acrylate material. In some embodiments, a rigid gas-permeable eyepiece can include cellulose acetate butyrate, siloxane acrylates, tert-butylstyrene, fluoromethyl acrylates, fluorosiloxane acrylates, perfluoroethers, fluorosilicones, tisilfocon A (C ₅₇ H ₈₃ F ₆ NO ₁₄ Si ₄ ), other types of polymers, or combinations thereof. These materials can include various combinations of monomers, polymers, and other materials to form the final polymer. For example, common components of these materials may include HEMA, HEMA-GMA, etc.

In some embodiments, a rigid ventilated eyepiece formed according to the methods and processes described herein may have physical characteristics that distinguish such a lens from rigid ventilated eyepieces formed according to other known methods. For example, in some embodiments, a rigid ventilated eyepiece formed according to the exemplary methods and processes described herein may have a lower average surface roughness ( _Ra ) compared to a rigid ventilated eyepiece formed by a known turning process. For example, in some embodiments, at least one of the front and/or rear surfaces of the rigid ventilated eyepiece may have a surface roughness of _Ra less than about 15 nanometers, less than about 10 nanometers, less than about 5 nanometers, less than about 4 nanometers, less than about 3 nanometers, less than about 2 nanometers, or less than about 1 nanometer or less.

In some examples, the dimensional tolerances of the rigid gas-permeable eyepieces formed according to the methods and processes described herein may be less than or equal to the dimensional tolerances specified by ISO for rigid gas-permeable eyepieces. In some embodiments, the dimensional tolerances of the rigid gas-permeable eyepieces may be less than about 0.009 mm, less than about 0.007 mm, less than about 0.006 mm, less than about 0.005 mm, less than about 0.004 mm, less than about 0.003 mm, or less than about 0.002 mm or smaller. As mentioned above, a manufacturing tolerance of around 0.2 mm is acceptable for conventional soft contact lenses. Conversely, the manufacturing tolerances of the exemplary rigid gas-permeable eyepieces manufactured according to the exemplary system and method are approximately ±3 to 5 micrometers.

Figure 1B illustrates an embodiment of a rigid gas permeable ocular orthokeratology lens 10 disposed on an eye 38 according to an exemplary embodiment. As shown, the visual zone 20 or the central back surface 22 of the lens (whose diameter is typically between 5.0 mm and 6.8 mm) covers a portion that can be considered the treatment area on the cornea. The base curve or back visual zone radius of the back surface 22 is designed based on the desired amount of central corneal flattening associated with corneal curvature, according to the desired myopia treatment. The radius can be selected using lens design calculations known as the Lessen formula. This theory assumes a linear relationship between myopia reduction and the selection of the base curve. In other words, if the corneal flattening K reading is 42.00D and Rx is –2.00D, a base curve of 40.00D can be fitted, which will change the corneal curvature and thus the desired amount of refraction change. The desired amount of myopia correction is identified according to the Lessen formula, referred to as the target prescription. The flat corneal meridian is then identified using dioptric power. An additional amount called a lessen factor is then added to the target prescription to make the baseline curve, or posterior visual radius, flatter than the flat corneal meridian. This lessen factor ranges from approximately 0.50D to approximately 3.00D. The lessen factor is added to ensure that the desired therapeutic dose is achieved and maintained throughout the day when the lens is removed and the cornea is relaxed.

Orthokeratology lenses can be designed to have a desired apical gap under a base curve, the apical gap ranging from 1 μm to 50 μm, preferably from 5 μm to 40 μm, more preferably from 15 μm to 25 μm, wherein a lower apical gap has a greater effect.

Additionally, as shown in Figure 1B, the corneal refractive lens includes a reversal zone 30, a release zone 32, an alignment zone 34, and a peripheral zone 36. The reversal zone connects the base curve or posterior radius to the release zone 32. As shown, the reversal zone is steeper than its adjacent curve and may include curves, splines, numerous tangents, and similarly designed linear reorientations. The reversal zone 30 defines a tear film reservoir 31, the depth of which can correspond to the amount of myopia being corrected. For low levels of correction, the tear film reservoir 31 can be shallower, while high levels of correction typically have a deeper tear film reservoir 31. The tear film reservoir 31 can vary from less than about 10 μm to about 80 μm or greater. The reversal zone 30 can raise or lower the base curve to achieve the desired apical gap. A steep reversal zone 30 increases the apical gap, while a relatively flat reversal zone decreases or sometimes eliminates the apical gap. Precisely forming the reverse zone avoids an overly steep reverse zone (leading to excessive apical gap and topographical center island) or an overly flat reverse zone (causing the lens to adhere to the top of the cornea instead of the periphery, resulting in lens decentering and eccentric treatment patterns).

As shown in the figure, release zone 32 connects the reverse zone 30 to the alignment zone 34. Release zone 32 (if present) is intended to facilitate the migration of epithelial cells from alignment zone 34 to the tear film reservoir. In some cases, the width of release zone 32 can vary from 0.4 mm to approximately 0.8 mm, while the depth or thickness can vary from approximately 10 μm to 20 μm.

Alignment zone 34 establishes a contact (landing) point for the corneal refractive lens and can be spherical, aspherical, or tangential. According to one embodiment, the alignment zone can be slightly aspherical to accommodate a wide variety of patients. The fit of alignment zone 34 facilitates proper lens alignment and determines the position where the lens rests on the eye.

Adjacent to the alignment zone 34, a peripheral zone 36 may be formed, which is any number of edge geometries to produce a suitable edge lift at the peripheral cornea. The peripheral zone 36 may have a width from 0.1 mm to 0.6 mm and a thickness from approximately 80 μm to 100 μm.

The design and selection of each of the aforementioned zones and curves can be modified according to the desired level of aggressiveness in treatment.

Figures 2A to 2C illustrate various components that can be used in some examples to form a rigid, gas-permeable eyepiece 10 according to the present exemplary system and method. Although the present exemplary system and method are described below primarily in the context of cast eyepieces formed in a two-piece mold, the system and method can also be applied to lenses manufactured by spin casting, casting molding, and/or to other forms of molded or cast contact lenses.

Regarding molded contact lenses, the shapes of the front and back surfaces of the lens are typically designed into the mold used to manufacture the lens. Figure 2A is a cross-sectional view of an embodiment of manufacturing a mold for producing a rigid gas-permeable eyepiece 10 according to the principles of the present invention. In this example, an injection molding process is used to form the mold, which is then used to form the rigid gas-permeable eyepiece 10. As shown, a standard injection molding machine can be used to form the mold. Specifically, material for the mold is fed into a material feed line 152 through a funnel 150 or other material reservoir. The material feed line 152 may include a screw 154, a propeller, or other types of mechanisms configured to move the molding material along the length of the material feed line 152. Additionally, a heating element 156 is applied to the material feed line to melt or at least soften the molding material as it passes through the material feed line 152. At the nozzle 158 of the material feed line 152, the molding material is extruded into the mold cavity 160, which is formed by the first part 162 and the second part 164 of the injection molded shell.

As shown in Figures 2A and 2B, the mold cavity 160 includes a punch tool 48 and a die tool 47 aligned with each other. According to one embodiment, the punch tool 48 and die tool 47 are made of tool steel. The extrusion pressure of the molding material entering the mold cavity 160 causes the molding material to fill all void spaces within the mold cavity 160, including the space between the punch tool 48 and die tool 47. The geometry of the punch tool 48 and die tool 47 is transferred to the resulting mold for casting the eyepiece 10. As shown in Figures 2B and 2C, the punch tool 48 of the casting mold may have a surface 49 corresponding to the front surface of the rigid ventilated eyepiece 10 to be formed. Furthermore, the surface 49 of the punch tool 48 may have the same degree of surface roughness and/or dimensional tolerances as the rigid ventilated eyepiece 10 to be formed.

Similarly, the casting molding process shown in Figures 2A to 2C can be used to form a punch portion of a casting molding system, which includes a surface defining the rear surface of the desired rigid ventilated eyepiece 10.

To generate surface 49, the punch tooling 48 is precisely machined or turned according to this exemplary system and method to match the desired features on the final rigid vent eyepiece to be produced. Similarly, the surface of the corresponding die tooling is precisely formed to define the desired rear surface of the final rigid vent eyepiece. Since the turned surface 49 of the punch tooling 48 ultimately corresponds to the formed front surface of the rigid vent eyepiece 10, the turned surface of the punch tooling 48 can be formed by a turning process that achieves at least the same level of precision and smoothness as desired in the rigid vent eyepiece 10.

Precise machining and forming methods can be used to form punch tooling, including, but not limited to, DAC ophthalmic lathes, visual ophthalmic lathes, FTS tooling, 5-axis diamond milling, 3D nanoprinting, nanolithography, fused deposition modeling, etc. In some embodiments, punch tooling 48 can be formed by a computer-controlled lathe or multi-axis milling machine, such as a visual ultra-precision lathe (models 30, 40, 50, and/or 80) available from Sterling Ultra Precision at 8600 Lagos-Merset Avenue, Florida. In some embodiments, the machine tool used to form punch tooling 48 can have a positioning resolution of 10 nanometers or less. In some embodiments, the turning and/or milling processes are precise enough that punch tooling 48 already has the desired surface properties to form the rigid, breathable eyepiece 10 as described herein, without additional processing (e.g., grinding or polishing). In other embodiments, the punch tooling 48 undergoes additional surface finishing treatments, including, but not limited to, grinding, polishing, lapping, honing, or ultra-precision machining.

After the molding material has hardened within the mold cavity 160 for a sufficient period of time, the first portion 162 and the second portion 164 are separated, and the mold is removed via the ejector pin 166, thereby producing the desired die component of the casting molding system. Similarly, the desired punch component of the casting molding system can be formed and ejected from the injection molding equipment.

While, for example, as described with reference to Figures 2A to 2C, in some embodiments the mold or a portion thereof may be formed by turning and injection molding processes, in other embodiments the mold may be formed by directly turning or machining a mold blank, thereby creating a profile for the die portion of the casting molding system to form the front surface of the rigid ventilated eyepiece 10, or a profile for the punch portion of the casting molding system to form the rear surface of the rigid ventilated eyepiece. Similarly, since the machined surface of the mold can form the front surface of the rigid ventilated eyepiece 10, the machined surface of the mold tooling 48 may be formed by a turning or milling process that achieves the same level of precision and smoothness as desired in the rigid ventilated eyepiece 10.

Figure 3 is a cross-sectional view of an embodiment of a casting molding system for casting a rigid gas-permeable eyepiece 10 according to the principles of the present invention. As shown, the casting molding system includes a punch member 300 having a convex rear forming surface 302 that defines the geometry and surface finish of the rear surface of the contact lens cast therein. Similarly, the casting molding system includes a die member 304 having a concave front forming surface 306 that defines the geometry and surface finish of the front surface of the contact lens cast therein. As shown in Figure 3, liquid RGP lens material can be disposed within the concave surface of the die member 304.

As described above, in some embodiments, the rear forming surface 302 of the punch member 300 and the front forming surface 306 of the die member 304 may have the same degree of smoothness and dimensional tolerances as the rigid, breathable eyepiece 10 to be formed. That is, in some examples, the dimensional tolerances of the punch member 300 and the die member 304 for the rear forming surface 302 and the front forming surface 306 may be less than about 0.009 mm, less than about 0.007 mm, less than about 0.006 mm, less than about 0.005 mm, less than about 0.004 mm, less than about 0.003 mm, or less than about 0.002 mm or smaller. In some embodiments, the contours of the rear forming surface 302 and the front forming surface 306 may have surfaces with a _Ra surface roughness of less than about 15 nm, less than about 10 nm, less than about 5 nm, less than about 4 nm, less than about 3 nm, less than about 2 nm, or less than about 1 nm or smaller. Furthermore, in some embodiments, the aforementioned smoothness and dimensional tolerances can be achieved directly in the mold tooling 48 through a turning or machining process, without requiring further processing, grinding, or polishing. Therefore, the precision achieved via this turning process can result in fewer processing steps, less waste, faster processing, and faster mold formation time compared to conventional processes (e.g., directly turning the surface of a rigid ventilated eyepiece), ultimately reducing the cost of the resulting rigid ventilated eyepiece 10.

Figure 4 is a cross-sectional view of an assembled casting molding system according to the principles of the present invention, wherein liquid lens material 308 is disposed between a punch member 300 and a die member 304 to conform to a rear forming surface 302 and a front forming surface 306. In this example, during assembly, the liquid lens material 308 is deposited into the contoured concave surface of the die member 304 and engaged by the rear forming surface 302.

Liquid lens material 308 can be made of any material suitable for use in rigid, breathable eyepieces. For example, liquid lens material 308 can be made of any rigid material that is breathable or oxygen-permeable during curing, polymerization, or hardening. In some embodiments, liquid lens material 308 may include polymeric materials. In some embodiments, liquid lens material 308 may include siloxane materials. In some embodiments, liquid lens material 308 may include acrylate materials. In some embodiments, liquid lens material 308 may include cellulose acetate butyrate, siloxane acrylates, tert-butylstyrene, fluorosiloxane acrylates, perfluoroethers, other types of polymers, or combinations thereof. These materials may include various combinations of monomers, polymers, and other materials to form the final polymer. For example, common components of these materials may include HEMA, HEMA-GMA, etc.

Liquid lens material 308 is suitable for molding from soft materials into rigid, non-zero gel final products. According to one embodiment, the viscosity of the liquid prepolymerized lens material at 20°C is between 10 centipoise (cps) and over 10,000 cps, between 100 cps and 8,000 cps, between 1,000 cps and 5,000 cps, or over 5,000 cps. Liquid prepolymerized lens material 308 is relatively viscous, but not so viscous as to distort the punch member 300, which could introduce air bubbles or distort the desired RGP lens. Additionally, liquid lens material 308 can be configured to flow and mold in an isotropic manner to maintain the designed dimensional effect. Specifically, liquid lens material 308 shrinks or expands isotropically, thereby allowing the designed dimensional effect to be maintained throughout the polymerization process and when subjected to shrinkage during long-term use. Historically, anisotropic shrinkage and dimensional distortion have hindered the molding of rigid, transparent eyepieces. The resulting polymer material forming the rigid, breathable eyepiece has a modulus of at least 500 MPa and may be greater than 800 MPa. The modulus can be measured according to ASTM D-1708a using an Instron (Model 4502) instrument, wherein the polymer sample is immersed in borate-buffered saline; suitable sample dimensions are a gauge length of 22 mm and a width of 4.75 mm, wherein the sample also has an end forming a canine bone shape to allow the sample to be held in the clamps of the Instron instrument, and the sample has a thickness of 200 ± 50 micrometers.

The resulting rigid, breathable eyepiece 10 can be shaped and sized based on various factors, including the shape and size of the user's eye, and the various optical properties or surface manipulation forces that the eyepiece is intended to achieve. The total thickness of the eyepiece 10 can be approximately 0.1 mm to approximately 0.14 mm. The thickness of the eyepiece 10 can gradually vary at different locations on the eyepiece 10. For example, the eyepiece 10 may be thicker near the outer edge of the eyepiece 10 compared to the viewing area, and vice versa.

Once the liquid lens material 308 is applied to the concave mold member 304 and engaged with the convex mold member 300, the liquid lens material 52 can then be exposed to a curing agent (e.g., temperature, photochemical radiation, or other types of curing agents or combinations thereof) until cured. As a result, the liquid lens material 308 forms a rigid ventilated eyepiece 10 having a front surface corresponding to the shape of the front forming surface 306 of the concave mold member 304 and a rear surface corresponding to the shape of the rear forming surface 302 of the convex mold member 300. Once the rigid ventilated eyepiece has cured, it can be removed.

Advantageously, the rigid ventilated eyepiece 10 formed according to the methods and processes described herein can have a higher surface smoothness than rigid ventilated eyepieces formed by other methods (e.g., by turning). For example, in some embodiments, at least one of the front and/or rear surfaces of the rigid ventilated eyepiece can have a surface roughness _Ra of less than about 15 nanometers, less than about 10 nanometers, less than about 5 nanometers, less than about 4 nanometers, less than about 3 nanometers, less than about 2 nanometers, or less than about 1 nanometer, or even smaller.

The process described herein can also result in the formation of a rigid ventilated eyepiece 10, which has a reduced amount of surface and interstitial imperfections compared to rigid ventilated eyepieces formed by conventional methods (e.g., turning processes). Smoothness and the absence of defects are particularly critical characteristics for the rear surface of the rigid ventilated eyepiece 10, as the rear surface directly contacts the user's eye. Therefore, if the surface is too rough or contains defects, it may cause irritation or discomfort to the user, and the rear surface can be configured to exert reshaping forces on the surface of the eye.

Compared to typical manufacturing processes (e.g., turning) used to form rigid ventilated eyepieces, casting allows for the simultaneous formation of multiple rigid ventilated eyepieces and allows for repeatability. These simultaneously formed lenses can have different geometries and can even be formed from different materials. The formation time for each lens is also typically shorter than that of a similar lens formed through a conventional turning process, and in some embodiments, the formed rigid ventilated eyepiece 10 may not require further post-forming processing to achieve the desired dimensional tolerances and smoothness. Furthermore, as described herein, the use of ultra-precision lathes and/or multi-axis milling machines to form the mold directly or via a mold blank and injection molding allows the cast rigid ventilated eyepiece 10 of the present invention to achieve the desired tolerances for rigid ventilated eyepieces that might previously only be achievable by directly turning rigid ventilated eyepieces. It was previously unimaginable that such precisely shaped rigid ventilated eyepieces could be formed by methods other than turning without post-forming processing (such as further turning, polishing, etc.).

Figure 5 illustrates an exemplary method for forming a die portion of a mold assembly used to form a rigid, gas-permeable eyepiece 10. As shown, the anterior surface geometry of the contact lens is designed (step 502). As previously mentioned, the use of sophisticated and smooth lathes and multi-axis milling machines allows for the design of previously unattainable non-rotationally symmetric geometries and shaping factors. This allows designs to include an imprinting effect on the user. The repeatability provided by this exemplary system and method is crucial for achieving optimal results when imprinting or altering the geometry of the user's cornea.

Once the front surface geometry has been designed, the design can be fed to a lathe and/or a multi-axis milling machine to machine the molding material (e.g., tool steel) to form a punch tooling having a surface corresponding to the designed front surface of the rigid, ventilated eyepiece (step 504). As mentioned above, the high-axis milling machine allows for extremely high tolerances (±3 to 5 micrometers) to meet the requirements of corneal corrective lenses.

When the mold tooling is completed, it can be incorporated into the injection molding system to form the cavity of the mold assembly, which includes a profile shaped to form the front surface of a rigid, breathable eyepiece (step 506).

Similarly, as shown in Figure 6, the corresponding punch of the mold assembly can be formed by the following steps: first, designing the geometry of the rear surface of the lens (step 602); processing mold material to form a die tool having a surface corresponding to the designed rear surface of the rigid ventilated eyepiece (step 604); and forming the punch of the mold assembly, which includes a contour shaped to form the rear surface of the rigid ventilated eyepiece (step 606).

Precise machining and forming methods can be used to form punch tooling, including but not limited to DAC ophthalmic lathes, visual ophthalmic lathes, FTS tooling, 5-axis diamond milling, 3D nanoprinting, nanolithography, fused deposition modeling, etc. In some embodiments, the punch tooling can be formed by a computer-controlled lathe, such as a visual ultra-precision lathe (models 30, 40, 50, and/or 80) available from Sterling Ultra Precision at 8600 Lagos-Merset Avenue, Florida. In some embodiments, the machine used to form the punch tooling can have a positioning resolution of 10 nanometers or less. In some embodiments, the turning process is precise enough that the punch tooling already has the desired surface properties to form the rigid, breathable eyepiece 10 as described herein, without additional processing (e.g., grinding, honing, lapping, or polishing).

As shown in Figure 7, once the two parts of the mold assembly have been manufactured, lens forming method 700 can be started by depositing liquid lens material onto the concave side of the die (step 702). Then, the punch member 300 and the die member 304 can be combined to distribute the liquid lens material around the rear and front forming surfaces of the mold (step 704). Once assembled, the liquid lens material can be cured via any number of curing mechanisms to form a rigid, breathable eyepiece (step 706).

Figure 8 shows a cross-sectional view of a rigid gas-permeable eyepiece 810 that interacts with the user's cornea 800 during use. While conventional soft contact lenses typically extend beyond the cornea and include an edge at least partially below the user's eyelid, corneal refractive lenses are smaller and engage directly with the user's eyelid each time the user blinks. This construction results in more eyelid/edge engagement. Due to this increased eyelid engagement, the conventional rigid gas-permeable eyepiece 810 achieves comfort through hand grinding, polishing, and abrasion. Similarly, the surface finish and quality of the edge 820 affect user comfort. Furthermore, to prevent corneal damage and discomfort, a corneal septum 830 should be designed and formed into the rigid gas-permeable eyepiece. According to an exemplary embodiment, the surface roughness _Ra of the molded rigid gas-permeable eyepiece is less than about 15 nanometers, less than about 10 nanometers, less than about 5 nanometers, less than about 4 nanometers, less than about 3 nanometers, less than about 2 nanometers, or less than about 1 nanometer, or smaller. Additionally, the corneal septum 830 is at least 2 nanometers or larger.

In addition to providing enhanced tolerances and complex non-rotationally symmetric designs, molding rigid gas-permeable eyepieces allows for additional design capabilities. As shown in FIG9, the molded multilayer rigid gas-permeable eyepiece 900 can be formed to have altered properties. According to an exemplary embodiment, separate molded layers 910, 920, 930, 940 can be molded and at least partially cured before the formation of subsequent layers. According to an exemplary embodiment, liquid lens material is at least partially cured to form the rigid gas-permeable eyepiece. In some embodiments, at least partially curing the separate molded layers of liquid lens material can include exposing the liquid lens material to a curing agent (e.g., photochemical radiation) as described herein. In some embodiments, the formed rigid gas-permeable eyepiece can have smoothness and dimensional tolerance characteristics as described herein; for example, the rigid gas-permeable eyepiece can have at least one surface with a _Ra surface roughness of less than about 5 nanometers. Once fully cured, the multilayer rigid gas-permeable eyepiece 900 can have layers with different refractive indices, diffraction arrays, features, powers, material properties, hardness, etc. According to an exemplary embodiment, additional elements may be introduced into each layer of the multilayer rigid breathable eyepiece 900, whereby these elements are encapsulated in the finally cured rigid breathable eyepiece.

Molded rigid gas-permeable eyepieces offer several advantages over conventionally lathe-machined rigid gas-permeable eyepieces. Specifically, this molding process provides a higher level of consistency in the final contact lens. When solid workpiece grains are machined to form conventional rigid gas-permeable eyepieces, each lens is different. Each cut imparts varying degrees of heat and different workpiece grain compositions to the lens, resulting in slight variations in the parameters of each machined lens. Additionally, each cut shifts the lens baseline. Furthermore, any changes to the prescription or the designed orthokeratology treatment require machining new lenses, which typically have longer lead times. Moreover, due to the high cost and long lead times of conventional rigid gas-permeable eyepieces, users often wear them for extended periods. Lenses used for extended periods typically undergo some shrinkage and damage, leading to gradual weakening or failure to achieve optimal performance over time.

In contrast, the molded rigid gas-permeable eyepieces disclosed herein have lower manufacturing costs and result in more consistent finished lenses because the process used to manufacture the lenses can be optimized for fineness, is iterative and repeatable, and can be performed quickly. Reduced manufacturing time and workload, along with lower costs, allow patients to change lenses more frequently. Therefore, the shrinkage and damage typically experienced by conventional rigid gas-permeable eyepieces can be eliminated.

Furthermore, the repeatability and precision offered by this method are particularly beneficial for orthokeratology lenses. The flexibility to make precise and controlled alterations to the contact lens design of rigid gas permeable lenses allows physicians to implement shape changes to the patient's eye more dynamically and controllably. In other words, optometrists can modify or adjust the radicalness of the eye shape changes they seek through the Jesson effect based on selective testing and monitoring. Radically altering the oval shape allows more light to enter the patient's eye (to control the growth of the myopic axis), but may be too radical to be consistently achieved, thus requiring the practitioner to repeatedly adjust the degree of radicalness. Due to the accuracy, repeatability, and cost advantages of this method, such changes are feasible and practical.

Additionally, as shown in FIG10, this exemplary system and method are not limited to rigid gas-permeable eyepieces intended for orthokeratology. Rather, this exemplary system and method can be used to form rigid gas-permeable eyepieces including a visual area and a non-visual area. According to an exemplary embodiment, this system and method can be used to form a scleral rigid gas-permeable eyepiece 1000. As shown, the scleral rigid gas-permeable eyepiece 1000 includes a pupillary area 1030 and a corneal area 1010 surrounding the visual area. Additionally, a scleral area 1020 is disposed outside the visual area. By using this exemplary system and method to manufacture a scleral rigid gas-permeable eyepiece, additional space is realized outside the visual area, where additional elements can be embedded in the lens to facilitate the functionality of a smart contact lens. For example, as shown in FIG10, an integrated circuit, sensor, or other sensing or computing device 1040 can be embedded within the scleral area 1020 of the scleral rigid gas-permeable eyepiece 1000. According to an exemplary embodiment, an integrated circuit, sensor, or other sensing or computing device 1040 can be embedded between the layers of the scleral rigid gas-permeable eyepiece 1000. The rigidity of the scleral rigidity and breathability eyepiece 1000 is used to protect the integrity of the integrated circuit, sensor, or other sensing or computing device 1040 and to extend its service life. Additionally, the integrated circuit, sensor, or other sensing or computing device 1040 can be communicatively connected to a power supply 1060 or other electrical components via a conductive path 1050 also located in the scleral region 1020. Any number of components can be embedded within the scleral region 1020, including, but not limited to, communication devices, sensors, lighting devices, diffraction arrays, etc.

While some of the examples described above have been specifically referred to in connection with the formation of rigid, ventilated eyepieces via a casting molding process, any suitable casting or molding process may be used to form rigid, ventilated eyepieces according to the invention. For example, in some embodiments, rigid, ventilated eyepieces may be formed by spin casting. Additionally, this exemplary system and method may be used to manufacture intraocular lenses, etc.

This exemplary system and method utilizes a multi-axis milling machine to meet the necessary high tolerance requirements of rigid gas-permeable eyepieces, particularly those that contact and reshape the cornea. This system and method allow rigid gas-permeable eyepieces to be formed from unique materials with low viscosity and low surface tension properties and in monomeric form to provide flow within the mold during manufacturing. Additionally, higher _DK values can be achieved with moldable materials compared to strictly machinable rigid gas-permeable materials (e.g., combinations of styrene dioxide and fluoromethyl methacrylate). The moldable materials described herein are capable of _DK values greater than 50, greater than 100, and/or greater than 150, according to units specified in ANSI Z80.20. Furthermore, the molding technique described herein for forming rigid gas-permeable eyepieces provides superior surface properties and physical finish on the lens compared to conventionally turned lenses. Molding also provides less inherent material stress (stress introduced when turning conventional rigid gas-permeable lenses). This reduction in material stress, resulting in less lens warpage, manifests itself as improved wettability and shape retention. Furthermore, by molding rigid, breathable eyepieces, additional materials can be added to the lens material without worrying about how the added materials will affect the machining process. For example, a surface modifier can be added and directly molded into the lens. Additionally, different front and rear surface finishes can be designed and introduced into the rigid, breathable eyepiece via a mold.

Molding also allows for complex surface shapes that were previously impossible, which could facilitate lens rotation, tear exchange, and prevent overnight adhesion. Furthermore, elements can be molded into the lens itself, such as windows of various shapes (circular, radial, linear, etc.).

Molding also allows for laminated or layered constructions, which enable the inclusion of alternative materials within a single rigid, breathable eyepiece. The included layers may include, but are not limited to, color modifiers, refractive index modifiers, drug delivery options (such as atropine, pyrrolizine), etc.

This exemplary system allows for advantages over conventional overnight orthokeratology lenses, including, but not limited to, a consistent geometry between lenses compared to conventionally turned lenses, providing an enhanced imprinting effect on the user's eye, thereby maintaining the ability to form shape factors and higher-order shape factors between lenses; and the ability to form non-rotationally symmetric shapes and edge forms that better conform to the eye, thus enhancing user comfort. Compared to turned rigid gas-permeable eyepieces, edge and peripheral shape factors can be achieved, and thinner, smoother edge shapes can be achieved.

Terms referenced in the claims should be given ordinary and conventional meanings, which are determined by reference to relevant entries in widely used general dictionaries and/or relevant technical dictionaries, meanings commonly understood by those skilled in the art, etc. It should be understood that the broadest meaning given by any one or combination of these sources should be given to the claim terms (e.g., two or more relevant dictionary entries should be combined to provide the broadest meaning of the combination of entries, etc.), except where: (a) if a term is used in a manner more extended than its ordinary and conventional meaning, then the term should be given its ordinary and conventional meaning plus that additional extended meaning; or (b) if a term is referenced by the phrase “as used herein shall mean” or similar language (e.g., “in this document, the term means,” “as defined herein,” “for the purposes of this disclosure, the term shall mean,” etc.), then the term has been expressly defined as having a different meaning.

References to specific examples, the use of the word "i.e.," the use of the word "invention," etc., do not imply invoking exception (b) or otherwise limiting the scope of the listed claims. Except where exception (b) applies, nothing contained herein shall be construed as a disclaimer or denial of the scope of the claims.

The subject matter referenced in the claims is not commonly extended with any particular embodiment, feature, or combination of features shown herein, and should not be construed as such. This is true even if only a single embodiment of a particular feature or combination of features is shown and described herein. Therefore, the appended claims should be given the broadest interpretation in light of the prior art and the meaning of the claims.

As used herein, spatial or directional terms such as “left,” “right,” “front,” and “back” relate to the subject matter shown in the accompanying drawings. However, it should be understood that the described subject matter may take on various alternative orientations, and therefore such terms are not to be considered limiting.

Articles such as “the,” “a,” and “an” can indicate singular or plural. Furthermore, the word “or” should be interpreted as inclusive (e.g., “x or y” means one or both of x and y) when used without the preceding word “any” (or in other similar languages where “or” explicitly indicates exclusivity—e.g., only one of x or y).

The term "and/or" should also be interpreted as inclusive (e.g., "x and/or y" refers to one or both of x and y). Where "and/or" or "or" is used as a conjunction for a group of three or more items, the group should be interpreted as including a single item, all items together, or any combination or number of items. Furthermore, terms used in the specification and claims, such as have, having, include, and including, should be interpreted as synonymous with the terms include and comprise.

Unless otherwise stated, all figures or expressions used in this specification (except for the claims) (e.g., those describing dimensions, physical properties, etc.) shall in any case be understood to be modified by the term "approximately". At least and without attempt to apply the doctrine of equivalence to the claims, each numerical parameter listed in the specification or claims that is modified by the term "approximately" shall be interpreted based on at least the number of significant figures referenced and by the application of conventional rounding techniques.

It should be understood that all scopes disclosed herein encompass and support claims that list any and all subscopes or any and all individual values contained therein. For example, the stated range of 1 to 10 should be considered to encompass and support claims that list any and all subscopes or individual values between the minimum value of 1 and the maximum value of 10 and/or include the minimum value of 1 and the maximum value of 10; that is, all subscopes begin with a minimum value of 1 or greater and end with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, etc.) or any value from 1 to 10 (e.g., 3, 5.8, 9.9994, etc.).

Claims (17)

1. A method for forming a rigid, gas-permeable corneal corrective lens, the method comprising: Forming at least a portion of a contact lens mold including a first surface, the first surface having a contour shaped to form the front surface of the corneal corrective lens; Forming at least a portion of the contact lens mold including a second surface, the second surface having a contour shaped to form the posterior surface of the corneal corrective lens; A liquid lens material is applied to a first side of the portion of the contact lens mold between the first surface and the second surface, the liquid lens material comprising an isotropic material having a viscosity between 1000 and 5000 cps at 20°C; and The liquid lens material in the contact lens mold is solidified by exposing it to photochemical radiation to form the corneal corrective lens, which includes a reversal zone and a release zone, the reversal zone defining a tear film reservoir whose depth corresponds to the amount of myopia being corrected. 2. The method according to claim 1, wherein at least one surface of the rigid gas-permeable corneal corrective lens has a _Ra roughness of less than 5 nanometers. 3. The method according to claim 2, the method further comprising casting the rigid gas-permeable corneal corrective lens. 4. The method of claim 2, wherein at least a portion of the mold is not required to be polished prior to forming the rigid gas-permeable corneal corrective lens to produce the rigid gas-permeable corneal corrective lens with a _Ra roughness of less than 5 nanometers. 5. The method of claim 1, wherein forming at least a portion of the contact lens mold including the first surface comprises: Processing a first blank to form a convex injection mold fixture, the convex injection mold fixture having a first mold surface corresponding to the front surface of the corneal corrective lens; and The convex injection molding tooling is used to injection mold the portion of the mold, thereby forming the portion of the mold including the first surface; and Forming at least a portion of the contact lens mold including the second surface includes: Processing a second blank to form a concave injection mold tooling, the concave injection mold tooling having a second mold surface corresponding to the rear surface of the corneal corrective lens; and The concave injection molding tooling is used to injection mold the portion of the mold, thereby forming the portion of the mold including the second surface. 6. The method of claim 5, wherein machining the first blank and the second blank comprises using a multi-axis milling machine with a positioning resolution of less than 10 nanometers. 7. The method according to claim 1, wherein the dimensional tolerance of the radius of curvature of the posterior visual zone of the rigid gas-permeable corneal corrective lens is equal to or less than 0.005 mm. 8. The method of claim 7, wherein the rigid gas-permeable corneal corrective lens is configured to deform the surface of the user's eye. 9. The method according to claim 1, wherein: The rigid, breathable corneal corrective lens has a modulus greater than 500 MPa. 10. A method for forming a rigid, gas-permeable corneal corrective lens, the method comprising: A mold is provided, the mold including a first side having a contour shaped to form the rear surface of the rigid gas-permeable corneal corrective lens; Liquid lens material is dispensed onto the first side of a portion of the mold, the liquid lens material comprising an isotropic material having a viscosity between 1000 and 5000 cps at 20°C; and The liquid lens material is at least partially solidified by exposing it to photochemical radiation to form the rigid, gas-permeable corneal corrective lens; The rigid, gas-permeable corneal corrective lens described therein has a modulus greater than 500 MPa, and The corneal corrective lens includes a reverse zone and a release zone, the reverse zone defining a tear film reservoir whose depth corresponds to the amount of myopia being corrected. 11. The method of claim 10 further includes casting the rigid, gas-permeable corneal corrective lens. 12. A molded rigid gas-permeable corneal corrective lens, comprising: A molded lens body, the molded lens body comprising a front surface and a rear surface; The lens includes a viewing area, a reverse area, an alignment area, and a peripheral area formed on the posterior surface of the molded lens body, the reverse area defining a tear film reservoir with a depth corresponding to the amount of myopia being corrected, wherein the rigid gas-permeable corneal corrective lens has a modulus greater than 500 MPa and a _DK greater than 100. 13. The molded rigid gas-permeable corneal corrective lens according to claim 12, wherein the lens is cast. 14. The molded rigid gas-permeable corneal corrective lens of claim 12, wherein the lens body has a thickness varying from 10 μm to more than 80 μm. 15. The molded rigid gas-permeable corneal corrective lens of claim 12, wherein the lens is configured to be fixed to the cornea and defines a tip gap between the posterior surface and the cornea between 5 μm and 40 μm. 16. A method for forming a rigid, breathable eyepiece, the method comprising: Forming at least a portion of a mold including a first side, the first side having a profile shaped to form the front surface of the rigid, breathable eyepiece; A liquid lens material is applied to the first side of the portion of the mold, the liquid lens material comprising an isotropic material having a viscosity greater than 5000 cps at 20°C; and The rigid, breathable eyepiece is formed by at least partially solidifying the liquid lens material by exposing it to photochemical radiation. 17. A molded rigid, breathable eyepiece, comprising: A molded lens body, the molded lens body comprising a front surface and a rear surface; The rigid, breathable eyepiece has a modulus greater than 500 MPa and a D_{_K} greater than 100, and the liquid lens material used to manufacture the molded lens body comprises an isotropic material having a viscosity greater than 5000 cps at 20°C.