U.S. patent application number 15/414474 was filed with the patent office on 2017-05-11 for sacrificial molding process for an accommodating contact lens.
The applicant listed for this patent is OneFocus Vision, Inc.. Invention is credited to Marie Dvorak CHRIST, Richard CHRIST, Amitava GUPTA, Rick PAYOR, Steve WAITE.
Application Number | 20170131571 15/414474 |
Document ID | / |
Family ID | 57601265 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170131571 |
Kind Code |
A1 |
WAITE; Steve ; et
al. |
May 11, 2017 |
SACRIFICIAL MOLDING PROCESS FOR AN ACCOMMODATING CONTACT LENS
Abstract
A method to manufacture an accommodating contacting lens is
provided. A soft contact lens material precursor is placed into a
container and cured. The cured contact lens material is machined to
form an intermediate surface over which an accommodating lens
module is placed. Further precursor is placed onto the intermediate
surface and surrounding the lens module. This further precursor is
cured. Afterwards, the surface of the cured precursor or soft
contact lens material is machined to form a first surface of the
accommodating contact lens. Then, the opposite surface is machined
to form a second surface of the accommodating contact lens, thereby
forming the accommodating contact lens with the module disposed in
the interior. The first and second surfaces may be a posterior and
anterior surface, respectively, of the accommodating contact
lens.
Inventors: |
WAITE; Steve; (Fernandina
Beach, FL) ; GUPTA; Amitava; (Roanoke, VA) ;
PAYOR; Rick; (Cumming, GA) ; CHRIST; Richard;
(Fernandina Beach, FL) ; CHRIST; Marie Dvorak;
(Fernandina Beach, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OneFocus Vision, Inc. |
Fernandina Beach |
FL |
US |
|
|
Family ID: |
57601265 |
Appl. No.: |
15/414474 |
Filed: |
January 24, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US15/43315 |
Jul 31, 2015 |
|
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15414474 |
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62031324 |
Jul 31, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02C 7/048 20130101;
G02C 7/085 20130101; B29K 2825/06 20130101; B29D 11/00028 20130101;
G02C 2202/18 20130101; G02C 7/04 20130101; B29D 11/00134 20130101;
G02C 7/049 20130101; G02B 3/14 20130101; B29D 11/00048 20130101;
G02C 7/083 20130101; A61F 9/0017 20130101 |
International
Class: |
G02C 7/08 20060101
G02C007/08; G02C 7/04 20060101 G02C007/04; B29D 11/00 20060101
B29D011/00 |
Claims
1. A method of manufacturing an accommodating contact lens, the
method comprising: providing an accommodating contact lens module
and a contact lens covering material; encapsulating the
accommodating contact lens module in the contact lens covering
material; and machining one or more of an anterior or posterior
surface of the soft contact lens covering material having the
contact lens module encapsulated therein to form an optical
correction zone for a subject.
2. A method as in claim 1, wherein the accommodating contact lens
module comprises a free standing module prior to being covered with
the contact lens covering material.
3. A method as in claim 1, wherein the module comprises an index of
refraction similar to an index of refraction of the contact lens
covering material in order to transmit light refracted by the
anterior and posterior surfaces of the optical correction zone
through at least a portion of the module and inhibit optical
artifacts.
4. A method as in claim 1, wherein the accommodating contact lens
module comprises a free standing module comprising one or more of
an optical chamber, a support structure, one or more eyelid
engaging chambers, one or more extensions extending between the
optical chamber and the one or more chambers, or an anchor.
5. A method as in claim 4, wherein the accommodating contact lens
module comprises the free standing module comprising the optical
chamber, the support structure, the one or more eyelid engaging
chambers, the one or more extensions extending between the optical
chamber and the one or more chambers and the anchor, and wherein
the free standing module is configured such that the optical
chamber, the support structure, the one or more eyelid engaging
chambers, the one or more extensions extending between the optical
chamber and the one or more chambers and the anchor are connected
to each other prior to placement in the mold such that the module
comprises a self-supporting module capable of being lifted and
placed in the mold by grasping the one or more of the optical
chamber, the one or more eyelid engaging chambers, the one or more
extensions extending between the optical chamber, the one or more
chambers, or the anchor.
6. A method as in claim 5, wherein the module is grasped by an end
effector of a robot.
7. A method as in claim 4, wherein the module comprises the optical
chamber and the one or more eyelid engaging chambers and wherein
the optical chamber comprises an anterior membrane having an
anterior thickness and a posterior membrane having a posterior
thickness, the posterior thickness greater than the anterior
thickness, and wherein the one or more eyelid engaging chambers
comprises an anterior membrane having an anterior membrane
thickness greater than a posterior membrane thickness of the one or
more chambers .
8. A method as in claim 7, wherein an anterior surface of the
anterior membrane of the optical chamber comprises a convex
curvature and a posterior surface of the posterior membrane of the
one or more chambers comprises a convex surface.
9. A method as in claim 4, wherein module comprises the anchor and
the anchor comprises a flange comprising a plurality of openings
and wherein the plurality of openings is placed in the mold.
10. A method as in any one of claim 1, 4, or 5, wherein an
optically transmissive coupling fluid has been placed in the
accommodation module prior to encapsulating the module.
11. A method as in claim 10, wherein the fluid is pressurized
within the module when the module has been placed in the mold.
12. A method as in claim 1, wherein an optical chamber of the
module comprises an optical power when placed in the mold and
wherein the optical power is inhibited by the contact lens covering
material with the module encapsulated within the contact lens
covering material.
13. A method as in claim 12, the optical chamber comprises an
optically transmissive coupling fluid and the optical chamber
comprises a convexly curved anterior surface of an anterior
membrane when the module has been placed in the mold.
14. A method as in claim 13, the anterior membrane comprises an
elastic deflection and wherein the elastic deflection pressurizes
the optically transmissive coupling fluid when the module has been
placed in the mold.
15. A method as in claim 1, wherein the contact lens covering
material comprises one or more of a hydrogel, silicone, siloxane,
silicone hydrogel, galyfilcon A, senofilcon A, Comfilcon A,
Enfilcon A, polyacrylate, or polyhydroxyethylmethacrylate
(pHEMA).
16. A method as in claim 1, wherein providing the contact lens
covering material comprises filling a first casting cup with a
precursor of the contact lens covering material.
17. A method as in claim 16, wherein the first casting cup
comprises one or more of a polymer, thermoplastic, polymethyl
methacrylate (PMMA), polyethylene, polypropylene, polyvinyl
chloride, polytetraflouroethylene, polycarbonate, or bisphenol
A.
18. A method as in claim 16, wherein providing the contact lens
covering material further comprises curing the precursor of the
contact lens covering material to provide a first contact lens
covering material portion of the contact lens covering material in
the first casting cup.
19. A method as in claim 18, further comprising machining a surface
of the first contact lens covering material portion to form an
intermediate surface.
20. A method as in claim 19, wherein the surface of the first
contact lens covering material portion is machined with a diamond
turner.
21. A method as in claim 19, wherein the intermediate surface has a
concave configuration.
22. A method as in claim 19, wherein machining the surface of the
first contact lens covering material portion comprises engaging a
rod coupled to the first casting cup.
23. A method as in claim 22, wherein machining the surface of the
first contact lens covering material portion further comprises
actuating the attached rod.
24. A method as in claim 22, wherein encapsulating the
accommodating contact lens module in the contact lens covering
material comprises placing the accommodating contact lens module
and the precursor of the contact lens covering material onto the
intermediate surface.
25. A method as in claim 24, further comprising curing the
precursor of the contact lens covering material on the intermediate
surface to form a second contact lens covering material portion of
the contact lens covering material.
26. A method as in claim 25, wherein placing the precursor of the
contact lens covering material comprises engaging the casting cup
with a second casting cup, and wherein machining one or more of the
anterior or posterior surface of the contact lens covering material
having the accommodating contact lens module encapsulated therein
comprises machining a surface of the second contact lens covering
material portion to form a first surface of the optical correction
zone.
27. A method as in claim 26, wherein the surface of the second
contact lens covering material portion is machined with a diamond
turner.
28. A method as in claim 26, further comprising disengaging the rod
from the first casting cup and machining the first contact lens
covering material portion to form a second surface of the optical
correction zone.
29. A method as in claim 28, wherein machining the first contact
lens covering material portion comprises engaging one or more of
the first or second casting cups.
30. A method as in claim 28, wherein the second surface of the
first contact lens covering material portion is machined with a
diamond turner.
31. A method as in claim 28, wherein the second surface of the
optical correction zone comprises an anterior surface.
32. A method as in claim 26, wherein the first surface of the
optical correction zone comprises a posterior surface.
33. A method of manufacturing a hydrogel, the method comprising:
combining a polymeric material precursor with a first diluent and a
second diluent; curing the bathed precursor to form a polymeric
material portion such that cure shrinkage of the polymeric material
portion is reduced by the first and second diluents; and providing
water to the polymeric material portion such that the first and
second diluents in the polymeric material portion are exchanged
with the water to form the hydrogel, wherein water expansion of the
polymeric material portion is inhibited with the first and second
diluents.
34. A method as in claim 33, wherein exchanging the first and
second diluents with the water softens the polymeric material.
35. A method as in claim 33, wherein combining the precursor of the
polymeric material in the first and second diluents comprises
mixing the precursor of the polymeric material with a combination
of the first and second diluents, the combination comprising a
molarity substantially equimolar with a molarity of the water.
36. A method as in claim 33, wherein the first and second diluents
in the polymeric material portion are exchanged with the water such
that the exchanged first and second diluents and the exchanged
water are substantially equimolar.
37. A method as in claim 33, wherein the first diluent comprises a
high molecular weight diluent and the second diluent comprises a
low molecular weight diluent.
38. A method as in claim 37, wherein the high molecular weight
diluent comprises a high molecular weight (MW) compound with a MW
of at least about 600 Da and the low molecular weight diluent
comprises a low MW compound with a MW of less than 100 Da.
39. A method as in claim 33, wherein the first diluent comprises a
high density diluent and the second diluent comprises a low density
diluent.
40. A method as in claim 39, wherein the high density diluent has a
density of greater than 0.8 g/cc and the low density diluent has a
density of less than 0.8 g/cc.
41. A method as in claim 33, wherein the first diluent comprises a
high viscosity diluent and the second diluent comprises a low
viscosity diluent.
42. A method as in claim 41, wherein the high viscosity diluent has
a viscosity of greater than 50 centiStokes (cSts) and the low
viscosity diluent has a viscosity of less than 50 cSts.
43. A method as in claim 33, wherein the first diluent comprises
one or more of polyethylene glycol (PEG) with molecular weights in
the range 600-4,500 Da.
44. A method as in claim 33, wherein the second diluent comprises
one or more of an alcohol, isopropyl alcohol, ethanol, methanol, or
a glycerol solution.
45. A method as in claim 33, wherein curing the bathed precursor to
form the polymeric material portion comprises heating the bathed
precursor.
46. A method as in claim 33, wherein curing the bathed precursor
comprises exposing the bathed precursor with UV radiation.
47. A method as in claim 33, wherein curing the bathed precursor
comprises photocuring the bathed precursor.
48. A method as in claim 33, wherein the precursor comprises a
photochemical polymerization initiator.
49. A method as in claim 33, wherein the precursor comprises a
monomer.
50. A method as in claim 49, wherein the monomer comprises
hydrophilic components.
51. A method as in claim 49, wherein molecular structure of the
hydrophilic components comprises one or more of acrylates,
methacrylates, vinyl, allyl, or other olefinic groups capable of
undergoing addition polymerization.
52. A method as in claim 33, wherein the precursor comprises a
cross-linker.
53. A method as in claim 52, wherein the cross-linker comprises one
or more of triacrylates or tetraacrylates.
54. An accommodating contact lens, comprising: an optically
transparent body comprising an anterior surface and a posterior
surface shaped to correct vision of the patient; an accommodation
module contained within the body; wherein one or more of the
anterior surface or the posterior surface comprises a surface
machined to correct vision of the patient.
55. An accommodating contact lens as in claim 54, wherein the one
or more surfaces comprises structure of the machining process.
56. A method of manufacturing a contact lens, the method
comprising: Placing a contact lens module in a mold; Providing a
polymeric material comprising a low molecular weight diluent and a
high molecular weight diluent; Curing the polymeric material to
form one or more optical surfaces of the contact lens with one or
more surfaces of the mold.
57. A method as in claim 56, wherein the one or more surfaces of
the mold forms one or more of an anterior optical surface or a
posterior optical surface of the contact lens.
58. A method as in claim 57, wherein the mold forms the anterior
optical surface and the posterior optical surface of the contact
lens.
59. A composition, the composition comprising: A polymeric
material; and A plurality of diluents contained within the
polymeric material, wherein the polymeric material comprises a
stiff material.
Description
CROSS-REFERENCE
[0001] The present application is a continuation of PCT Application
Ser. No. PCT/US2015/043315, filed Jul. 31, 2015, entitled
"Sacrificial Molding Process for an Accommodating Contact Lens"
(attorney docket no. 44910-707.601), which claims priority to U.S.
application Ser. No. 62/031,324, filed Jul. 31, 2014, entitled
"Sacrificial Molding Process for an Accommodating Contact Lens"
(attorney docket no. 44910-707.101), the entire disclosure of which
is incorporated herein by reference.
[0002] This subject matter of the present application is related to
the following patent applications: PCT/US2014/013427, filed on 28
Jan. 2014, entitled "Accommodating Soft Contact Lens" (attorney
docket no. 44910-703.601); U.S. application Ser. No. 61/757,457,
filed on Jan. 28, 2013, entitled "An Accommodating Soft Contact
Lens" (attorney docket no. 44910-703.102); PCT/US2014/013859, filed
on Jan. 30, 2014, entitled "Manufacturing Process of an
Accommodating Contact Lens" (attorney docket no. 44910-704.601);
U.S. application Ser. No. 61/758,416, filed on Jan. 30, 2013,
entitled "Manufacturing Process of an Accommodating Soft Contact
Lens" (attorney docket no. 44910-704.101); U.S. application Ser.
No. 61/857,462, filed Jul. 23, 2013, entitled "Manufacturing
Process of an Accommodating Soft Contact Lens II" (attorney docket
no. 44910-704.102); PCT/US2014/071988, filed on Dec. 22, 2014,
entitled "Fluidic Module For Accommodating Soft Contact Lens"
(attorney docket no. 44910-705.601); U.S. application Ser. No.
61/919,691, filed on Dec. 20, 2013, entitled "Fluidic Meniscus
Module for Accommodating Soft Contact Lens" (attorney docket no.
44910-705.101); U.S. Provisional Application Ser. No. 62/031,290,
filed on Jul. 31, 2014, entitled "Fluidic Meniscus Module for
Accommodating Soft Contact Lens" (attorney docket no.
44910-705.102); and U.S. Provisional Application Ser. No.
62/031,305, filed on Jul. 31, 2014, entitled "Control Device
Responsive to Lid Fissure Width" (attorney docket no.
44910-706.101), the entire disclosures of which are incorporated
herein by reference.
BACKGROUND
[0003] The present invention relates generally to the treatment
presbyopia.
[0004] As the eye ages, the lens of the eye become less capable of
moving to provide variable optical power, a condition referred to a
presbyopia. In young subjects, the lens of the eye can accommodate
viewing at various distances, so that the user can be both near and
far object with clear focus. However as the eye ages, the lens of
the eye becomes less capable of accommodating both near and far
vision and subjects with good far vision may benefit from glasses
to read close objects.
[0005] Prior methods and apparatus of treating presbyopia provide
less than ideal treatment in at least some respects. Prior
treatments of presbyopia include bifocal spectacles, progressive
addition lenses, and multifocal contact lenses, as well as reading
glasses and accommodating intraocular lenses. At least some
subjects are spectacle intolerant, and spectacles can be difficult
to wear in at least some situations. Multi focal lenses can degrade
vision at both near and far vision at least partially in at least
some instances. Intraocular lenses require surgery and can be more
invasive that would be ideal in at least some instances.
[0006] Although multifocal contact lenses have been proposed, such
lenses produce less than ideal results in at least some instances.
Multifocal contact lenses may have two or more optical zones of
different optical power. In at least some instances, one of these
zones of different optical power can transmit light to the eye that
is out of focus on the retina and degrades vision of the subject.
Although contact lenses that translate on the cornea have been
proposed in order to provide variable focus, such lenses can be
somewhat difficult for subjects to use and provide less than ideal
results in at least some instances. Examples of multifocal contact
lenses are described in Patent Nos. U.S. Pat. No. 7,517,084; U.S.
Pat. No. 7,322,695; U.S. Pat. No. 7,503,652; U.S. Pat. No.
6,092,899; and U.S. Pat. No. 7,810,925, for example.
[0007] Although accommodating contact lenses have been previously
proposed, the prior accommodating contact lenses can be less than
ideal in at least some instances. For example, the optical
properties of the prior accommodating contact lenses can be less
than ideal. For example, the shape of the central shape changing
region of the prior accommodating contact lenses can be somewhat
distorted when the eye accommodates, and the accommodating optical
zone can be somewhat smaller than would be ideal. Also, the optical
zones the prior lenses can be shaped somewhat irregularly and may
provide less than ideal changes in optical power. Also, the
materials of the prior accommodating contact lenses can be less
than ideally suited for combination with known contact lens
materials, and the extent to which prior accommodating contact
lenses can be worn on the eye is less than ideal in at least some
instances. Accommodating contact lenses are described in WO
91/10154; U.S. Pat. No. 7,699,462; U.S. Pat. No. 7,694,464; and
U.S. Pat. No. 7,452,075, for example.
[0008] In addition to the deficiencies noted above, work in
relation to embodiments also suggests that the prior accommodating
contact lenses are less than ideally suited for manufacturing, and
that at least some of the prior accommodating contact lenses may be
difficult to produce in large volumes in at least some instances.
The prior methods and apparatus for manufacturing contact lenses
can be less than ideally suited to provide contact lenses having
different materials. In at least some instances, the prior methods
and apparatus of manufacturing contact lenses with different
materials can provide less than ideal integration into a contact
lens, for example. In at least some instances, the dissimilar
materials can have different amounts of shrinkage and expansion
during the manufacturing process, which can cause different layers
of material to induce distortions to the contact lens and in some
instances separate, for example delaminate, in at least some
instances. Also, the prior methods and apparatus can be less than
ideally suited for positioning components composed of different
materials within contact lenses. For example, pre-positioning a
component in a contact lens mold and manufacturing the component
can be more difficult than would be ideal in at least some
instances.
[0009] Work in relation to embodiments suggests that the
formulations of the precursor material for the accommodating
contact lenses can provide less than ideal integration with the
embedded accommodation module, and that the prior materials for
such contact lenses can be less than ideal. For example, dissimilar
materials can be less than ideally coupled together in at least
some instances. Adhesion of the dissimilar lens materials can be
less than ideal. Work in relation to embodiments suggest that a
non-hydrogel material coupled to a hydrogel material can provide
less than ideal contact, and the curing process can be related to
imperfections such as pooling, less than ideal adhesion, or
bubbles, for example.
[0010] In light of the above, it would be desirable to provide
improved methods and apparatus for manufacturing contact lenses.
Ideally, such methods and apparatus would provide an improved
accommodating contact lens, facilitate manufacturing of the
accommodating contact lens, provide improved positioning of
components composed of dissimilar materials within the lens,
provide improved coupling of components within the lens, provide
quality near vision, intermediate and far vision, be compatible
with known safe contact lens materials, and be readily
manufactured. At least some of these objectives are met with the
embodiments as disclosed herein.
SUMMARY
[0011] Embodiments of the present invention provide improved
methods and apparatus for manufacturing accommodating contact
lenses and improved accommodating contact lenses and methods of
use. Although specific reference is made to contact lenses, the
embodiments disclosed herein can be used in one or more of many
fields such as astronomy, machine vision, and digital cameras.
[0012] In many embodiments, one or more surfaces of a contact lens
is machined to an optical surface with components of the
accommodating contact lens embedded in a contact lens covering
material. The machined surface may comprise one or more of an
anterior surface or a posterior surface of the accommodating
contact lens. In many embodiments, a pre-configured self supporting
module is covered in a soft contact lens material, in order to
provide seamless integration of the module within the contact lens
body comprising the module and the contact lens covering material.
In many embodiments, the module is embedded in the contact lens
covering material coating the module and shaped to provide optical
correction of the user. In many embodiments, the module is placed
in a mold and the covering material cured around the module to form
a contact lens body. While the mold can be provided in one or more
of many ways, in many embodiments the mold comprises a sacrificial
mold that can be machined away to form an optical surface of the
accommodating contact lens.
[0013] The covering material can be soft when placed on the eye,
and one or more of stiff, firm or rigid during one or more
manufacturing steps and prior to placement on the eye. The covering
material can comprise one or more of many polymer precursor
materials such as a monomer. In many embodiments, the covering
material comprises a diluent combined with the precursor material
prior to curing that inhibits a change in volume when replaced with
water during hydration. The methods and apparatus disclosed herein
can fixedly embed the module in the contact lens body material,
such that the module remains fixed in the covering material during
steps of the manufacturing process and when hydrated and placed on
the eye. This fixing of the module in the contact lens material
allows the contact lens to be machined to optical tolerances in
order to treat refractive error of the eye and in at least some
embodiments one or more aberrations of the eye such as spherical
aberration and coma.
[0014] In many embodiments, and accommodating contact lens module
is provided for use with an accommodating contact lens. Components
of the accommodating contact lens module can be manufactured and
assembled with low distortion optics to provide improved vision,
and the module may comprise a self-supporting free standing module
capable of being grasped by one of the components and placed in a
mold without distorting the optical components of the module when
placed. In many embodiments, the module is compatible with soft
contact lens materials, such as hydrogels and silicones, and
compatible with soft contact lens manufacturing processes such as
molding of hydrogels and silicones.
[0015] The module may comprise one or more of many components that
can be placed in the mold together. The module may comprise one or
more of an optical chamber, a support structure extending around
the optical chamber, one or more eyelid engaging chambers, one or
more extensions extending between the one or more eyelid engaging
chambers and the optical chamber, or one or more anchors. Each of
these components can be placed in the mold for encapsulation in
order to provide accurate optical correction of the eye of the
subject, for both far vision and near vision. In many embodiments,
the module is inspected prior to placement in the mold. In many
embodiments, the optical properties of the module such as optical
power and change in optical power are determined prior to placement
in the mold in order to provide a functional accommodating contact
lens to the eye of the subject.
[0016] The components can be assembled and connected in one or more
of many ways such as by welding such as laser welding or an
adhesive to seal the module which may be hermetically sealed. In
many embodiments, the module comprises a plurality of eyelid
engaging chambers arranged for cumulative far vision, intermediate
vision and near vision correction, respectively, with additional
add power as the eyelid successively engages the plurality of
chambers. The chambers of the module can be filled with fluid prior
to placing the module in the mold, and the module can be
pressurized prior to placement in the mold. The fluid can remain
pressurized when the accommodating contact lens has been removed
from the mold, packaged, and placed on the eye in order to increase
responsiveness and inhibit hysteresis of the accommodating contact
lens. In many embodiments, module comprises one or more membranes
to inhibit leakage of the fluid, and the fluid is placed in the
module to inhibit bubble formation, such as with degassing of the
fluid prior to placement in the sealed module and orientation of
the module when fluid is drawn into the module.
[0017] In many embodiments, module is encapsulated within the mold
in order to inhibit optical properties of the module and correct
vision of the eye. The mold may comprise a convexly curved male
portion corresponding to a base curvature of the cornea of the eye
and a concavely curved optically corrective female potion having a
concave surface profile corresponding to a refractive error of the
eye. The module can be encapsulated within the mold to form the
anterior and posterior surfaces of the accommodating contact lens
with shape profiles for the optical correction of the eye and for
fitting the contact lens on the cornea of the eye, respectively. In
many embodiments, the accommodating contact lens module comprises
an optically transparent material having an index of refraction
similar to the soft contact lens material such that light can be
transmitted through module without introducing perceptible visual
artifacts.
[0018] The module can be encapsulated in the contact lens material
in one or more of many ways. In many embodiments, a precursor
material is placed on the module to provide a layer of the
precursor material on the module. The layer of precursor material
on the module can ensure that at least a thin layer of the soft
contact lens material encapsulates the module. In many embodiments,
the module is wettable by the precursor material to provide the
layer on the module. The surface of the module can be treated so as
to comprise the wettable surface, such as with a plasma treatment
to form hydroxyl groups on the surface of the module. The precursor
material may comprise one or more of a monomer, a partially cured
monomer, an oligomer, or a pre-polymer. In many embodiments, the
module is placed in the mold with the precursor material, and the
precursor material comprises an amount of viscosity sufficient to
form a layer having a thickness suitable for encapsulation. In many
embodiments, the precursor material is partially cured to provide
the viscosity in order to form the layer with the thickness. The
module may comprise a density greater than the precursor material,
such that the module settles in the precursor material with the
layer extending between the module and the mold. The precursor
material can be cured with the layer extending between one or more
surfaces of the module and the mold order to encapsulate the module
and provide the encapsulating contact lens material with the
thickness when worn on the eye. In many embodiments, the layer
comprises a thickness sufficient to inhibit tearing of the layer
away from the one or more components of the module. In many
embodiments, the soft contact lens comprises an anterior layer
comprising an anterior thickness on an anterior an anterior side
extending between the anterior surface of the module and the
anterior surface of the lens, and a posterior layer comprising a
posterior thickness on posterior side extending between the
posterior surface of the module and the posterior surface of the
lens, in which the anterior layer is thinner than the posterior
layer in order to facilitate anterior movement of the anterior
membrane of the optical chamber. In many embodiments, the anterior
thickness is determined at least in part by the viscosity of the
precursor material, such that the precursor material can be
provided with a viscosity in order to form the soft contact lens
material with an appropriate anterior thickness.
[0019] The module can be placed in the mold in one or more of many
ways. In many embodiments, the mold comprises a concavely curved
lower female portion oriented upward in order to receive the
precursor material and the module, and a convexly curved upper male
portion oriented downward to fit with the female portion when the
module and precursor material have been placed. In many
embodiments, an anterior surface of the module is oriented downward
toward the concave surface of the mold, with an anterior layer of
precursor material extending between the anterior surface of the
module and the concave surface of the mold. The convex surface of
the male portion of the mold can be advanced toward the concave
surface of the female portion into mating engagement with the
female portion in order to form the posterior surface of the
accommodating contact lens when the precursor material has
cured.
[0020] Aspects of the present disclosure may provide a method of
manufacturing an accommodating contact lens. An accommodating
contact lens module and a soft contact lens material may be
provided. The accommodating contact lens module may be encapsulated
in the soft contact lens material. One or more of an anterior or
posterior surface of the soft contact lens material having the
contact lens module encapsulated therein may be machined to form an
optical correction zone for a subject.
[0021] The accommodating contact lens module may comprise a free
standing module. The module may comprises an index of refraction
similar to an index of refraction of the soft contact lens material
in order to transmit light refracted by the anterior and posterior
surfaces of the optical correction zone through at least a portion
of the module and inhibit optical artifacts.
[0022] The accommodating contact lens module may comprises a free
standing module comprising one or more of an optical chamber, a
support structure, one or more eyelid engaging chambers, one or
more extensions extending between the optical chamber and the one
or more chambers, or an anchor. The accommodating contact lens
module may comprise the free standing module comprising the optical
chamber, the support structure, the one or more eyelid engaging
chambers, and the one or more extensions extending between the
optical chamber and the one or more chambers and the anchor. The
free standing module may be configured such that the optical
chamber, the support structure, the one or more eyelid engaging
chambers, the one or more extensions extending between the optical
chamber and the one or more chambers and the anchor are connected
to each other prior to placement in the mold such that the module
comprises a self-supporting module capable of being lifted and
placed in the mold by grasping the one or more of the optical
chamber, the one or more eyelid engaging chambers, the one or more
extensions extending between the optical chamber, the one or more
chambers, or the anchor. The module may be grasped by an end
effector of a robot.
[0023] The module may comprise the optical chamber and the one or
more eyelid engaging chambers. The optical chamber may comprise an
anterior membrane having an anterior thickness and a posterior
membrane having a posterior thickness. The posterior thickness may
be greater than the anterior thickness. The one or more eyelid
engaging chambers may comprise an anterior membrane having an
anterior membrane thickness greater than a posterior membrane
thickness of the one or more chambers. The anterior surface of the
anterior membrane of the optical chamber may comprise a convex
curvature. A posterior surface of the posterior membrane of the one
or more chambers may comprise a convex surface. The module may
comprise the anchor and the anchor may comprise a flange comprising
a plurality of openings which may be placed in the mold.
[0024] An optically transmissive coupling fluid may have been
placed in the accommodation module prior to encapsulating the
module. The fluid may be pressurized within the module when the
module has been placed in the mold.
[0025] An optical chamber of the module may comprise an optical
power when placed in the mold. The optical power may be inhibited
by the soft contact lens material with the module encapsulated
within the contact lens material. The optical chamber may comprise
an optically transmissive coupling fluid. The optical chamber may
comprise a convexly curved anterior surface of an anterior membrane
when the module has been placed in the mold. The anterior membrane
may comprise an elastic deflection. The elastic deflection may
pressurize the optically transmissive coupling fluid when the
module has been placed in the mold.
[0026] The soft contact lens material may comprise one or more of a
hydrogel, silicone, siloxane, silicone hydrogel, galyfilcon A,
senofilcon A, Comfilcon A, Enfilcon A, polyacrylate, or
polyhydroxyethylmethacrylate (pHEMA).
[0027] To provide the soft contact lens material, a first casting
cup may be filled with a precursor of the contact lens material.
The first casting cup may comprise one or more of a polymer,
thermoplastic, polymethyl methacrylate (PMMA), polyethylene,
polypropylene, polyvinyl chloride, polytetraflouroethylene,
polycarbonate, or bisphenol A. The soft contact lens material may
further be provided by curing the precursor of the contact lens
material to provide a first soft contact lens material portion of
the soft contact lens material in the first casting cup. A surface
of the first contact lens material portion may be machined, such as
with a diamond turner, to form an intermediate surface. The
intermediate surface may have a concave configuration. The surface
of the first contact lens material portion may be machined by
engaging a rod to the first casting cup and actuating the attached
rod such as by rotation.
[0028] To encapsulate the accommodating contact lens module in the
soft contact lens material, the accommodating contact lens module
and the precursor of the soft contact lens material may be placed
onto the intermediate surface. The precursor of the contact lens
material on the intermediate surface may be cured to form a second
contact lens material portion of the contact lens material. To
place the precursor of the soft contact lens material on the
intermediate surface, the first casting cup may be engaged with a
second casting cup. A mold may be thus formed between the first and
second casting cups and the precursor may be introduced into the
mold.
[0029] One or more of the anterior or posterior surface of the
contact lens material having the accommodating contact lens module
encapsulated therein may be machined such as by machining a surface
of the second contact lens material portion (e.g., with a diamond
turner) to form a first surface of the optical correction zone. To
form a second surface of the optical correction zone, the machining
rod may be disengaged from the first casting cup and the first soft
contact lens material portion may be machined (e.g., with a diamond
turner) to form a second surface of the optical correction zone. To
machine the first contact lens material portion here, the one or
more of the first or second casting cups may be engaged. The first
surface of the optical correction zone may comprise a posterior
surface and the second surface of the optical correction zone may
comprise an anterior surface and vice versa. To complete the
accommodating contact lens, the first and second casting cups may
be machined or dissolved away leaving only the contact lens.
[0030] Aspects of the present disclosure provide methods, apparatus
and compositions for manufacturing a hydrogel material. In many
embodiments a polymeric material precursor is combined with a first
diluent and a second diluent, cured to form a polymeric material,
then placed in water to remove the diluents. The first and second
diluents may modulate the polymerization reaction to reduce
shrinkage during curing, and can also reduce water expansion of the
cured polymeric material upon exchange of the diluent with
water.
[0031] In many embodiments, exchanging the diluents with water
softens the polymeric material to form a hydrogel.
[0032] In many embodiments, the first and second diluent are
provided such that the molar volume of the combined diluents is
equal to or close to the molar volume of water, in order to inhibit
the expansion of the cured monomer when the diluent is replaced
with water.
[0033] In many embodiments, the first diluent comprises a high
molecular weight component with relatively high density and
viscosity, and the second diluent comprises a low molecular weight
component with relatively low density and viscosity. The high
density and viscosity of the first diluent may reduce cure
shrinkage. The low density of viscosity of the second diluent may
inhibit expansion of the cured polymer upon replacement of the
diluent with water. The first diluent may comprise one or more of
many high molecular weight substances such as one or more of many
polyethylene glycol molecules having a molecular weight in the
range 600-4,500 Da, and the first diluent may comprise a
composition of a plurality of high molecular weight molecules
having a molecular weight in the range of 600-4500 Da. The second
diluent may comprise one or more of isopropyl alcohol, ethanol,
methanol, or a glycerol solution. The first diluent may comprise
one or more of a polyol, polyether diol, polyethylene glycol,
polypropylene glycol, and poly(tetramethylene ether) glycol.
[0034] In many embodiments, the precursor material combined with
the diluent solution may be cured by heating the precursor, or by
exposing the precursor to UV radiation.
[0035] In many embodiments, the precursor material comprises
hydrophilic monomer components, cross-linker components, and
photo-initiator components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0037] FIG. 1 shows a top view of the fluidic module embedded in a
contact lens upon primary gaze, in which the fluidic module
comprises a central chamber and several peripheral chambers,
interconnected via micro-channels;
[0038] FIGS. 2A to 2C show design of the fluidic module and
chambers, in accordance with embodiments;
[0039] FIG. 3 shows a top view of the fluidic module, comprising a
central chamber and several peripheral chambers, interconnected via
micro-channels, upon downward gaze, in accordance with
embodiments;
[0040] FIG. 4 shows a flow chart of assembly of the fluidic module,
in accordance with embodiments;
[0041] FIG. 5 shows filling and sealing of the fluidic module, in
accordance with embodiments;
[0042] FIG. 6 shows a process of molding and forming a soft contact
lens made of a hydrophilic monomer or a silicone hydrogel modified
to add the inclusion of a fluidic module, fabricated as shown in
FIG. 5, in accordance with embodiments;
[0043] FIG. 7 shows a schematic of a mold surface for forming an
accommodating contact lens, in accordance with embodiments;
[0044] FIG. 8 shows the mold surface of FIG. 6 in use with a cup to
form a mold for forming the accommodating contact lens, in
accordance with embodiments;
[0045] FIG. 9 shows an intermediate lens formed with the mold of
FIG. 7, in accordance with embodiments;
[0046] FIG. 10 shows an accommodating lens module placed over the
intermediate lens of FIG. 8, in accordance with embodiments;
[0047] FIG. 11 shows the intermediate lens and accommodating lens
module of FIG. 9 in use with a second cup to form a mold for
completing the accommodating contact lens, in accordance with
embodiments;
[0048] FIG. 12 shows the completed accommodating contact lens over
the mold surface of FIG. 6, in accordance with embodiments;
[0049] FIG. 13 shows a process of molding and forming a soft
contact lens comprising a fluidic module, fabricated as shown in
FIGS. 7-12, in accordance with embodiments;
[0050] FIG. 14 shows a perspective view of a casting cup, in
accordance with embodiments;
[0051] FIG. 15 shows a perspective view of the casting cup of FIG.
14 filled with a cured monomer formulation, in accordance with
embodiments;
[0052] FIG. 16 shows a side, sectional view of the casting cup of
FIG. 15 with a machined intermediate surface of the cured monomer
formulation, in accordance with embodiments;
[0053] FIG. 17 shows a perspective view of the casting cup of FIG.
16 with an accommodating lens module placed into the intermediate
surface, in accordance with embodiments;
[0054] FIG. 18 shows a perspective view of the casting cup of FIG.
17 with a second layer of cured monomer formulation placed over the
intermediate surface and the module , in accordance with
embodiments;
[0055] FIG. 19 shows a perspective view of a concave lens surface
formed on the cured monomer formulation in the casting cup of FIG.
18, in accordance with embodiments;
[0056] FIG. 20 shows a perspective, sectional view of the casting
cup of FIG. 18 attached to a block, in accordance with
embodiments;
[0057] FIG. 21 shows a side, sectional view of the casting cup and
attached block of FIG. 20, in accordance with embodiments;
[0058] FIG. 22 shows a perspective view of the machined convex lens
surface on the cured monomer formulation in the casting cup of FIG.
21, in accordance with embodiments;
[0059] FIG. 23 shows a perspective view of the accommodating
contact lens formed from the process of FIGS. 14 to 22, in
accordance with embodiments;
[0060] FIG. 24 shows a process of molding and forming a soft
contact lens comprising a fluidic module, fabricated as shown in
FIGS. 14-23, in accordance with embodiments; and
[0061] FIG. 25 shows a table of some exemplary materials that the
monomer formulation may comprise, in accordance with
embodiments.
DETAILED DESCRIPTION
[0062] A better understanding of the features and advantages of the
present disclosure will be obtained by reference to the following
detailed description that sets forth illustrative embodiments, in
which the principles of embodiments of the present disclosure are
utilized, and the accompanying drawings.
[0063] Although the detailed description contains many specifics,
these should not be construed as limiting the scope of the
disclosure but merely as illustrating different examples and
aspects of the present disclosure. It should be appreciated that
the scope of the disclosure includes other embodiments not
discussed in detail above. other modifications, changes and
variations which will be apparent to those skilled in the art may
be made in the arrangement, operation and details of the method and
apparatus of the present disclosure provided herein without
departing from the spirit and scope of the invention as described
herein.
[0064] The inventors have developed solutions to the problems of
the prior art and disclose herein an improved design comprising a
fluidic module that may be embedded into a soft contact lens for
correction of presbyopia.
[0065] The embodiments disclosed herein can be combined in one or
more of many ways to provide improved accommodation of a contact
lens.
[0066] As used herein like characters identify like elements.
[0067] As used herein the words "top" or "upper" encompass the
anterior surface, away from the corneal surface, and the words
"bottom" or "lower" encompass the posterior surface, closest to the
corneal surface.
[0068] As used herein the letter "C" after a number in the context
of temperature encompasses degrees Celsius and Centigrade, as will
be readily understood by a person of ordinary skill in the art.
[0069] As used herein a dash "-" can be used to express a range of
values, as will be readily understood by a person of ordinary skill
in the art.
[0070] As used herein, the same index refraction encompasses an
index of refraction close enough to another index of refraction to
inhibit visual artifacts that might otherwise be perceptible to the
user.
[0071] As used herein, similar index refraction encompasses an
index of refraction close enough to another index of refraction to
inhibit visual artifacts.
[0072] As used herein, the term "process" is used interchangeably
with the term "method".
[0073] As used herein, a "soft" contact lens material encompasses a
material that is soft when placed on the eye, although the material
can be one or more of stiff, firm, or rigid, during one or more
manufacturing steps prior to placement on the eye.
[0074] The module and manufacturing process described herein are
well suited for combination with many known prior contact lenses
and manufacturing processes, such that the accommodating soft
contact lenses can be produced in large quantities, and are
compatible with many known prior contact lens configurations and
shapes. The anterior surface of the accommodating contact lens can
be configured to correct refractive error of the eye such as
sphere, cylinder and axis, and can be configured to correct
aberrations of the eye, such as spherical aberration and coma, for
example. The posterior surface of the accommodating contact lens
can be configured to fit the eye with one or more of many shapes
such as one or more spherical curvature profile, an elliptical
profile, or a plurality of curvatures, as may be appropriate to fit
one or more structures the eye such as the cornea, for example.
[0075] In many embodiments, the module comprises a stiffness
greater than the soft contact lens material. The stiffness of the
module can be configured in one or more of many beneficial ways to
provide low distortion optics and to inhibit tearing of the contact
lens material encapsulating the module, for example when the
contact lens is deflected. The stiffness of the module can range
from slightly stiffer than the soft contact lens material such as a
hydrogel, to substantially stiffer than the encapsulating contact
lens material. Although the module may comprise one or more
components comprising stiffness to add rigidity, in many
embodiments the module comprises both stiffness to provide low
distortion optics and sufficient compliance so as to bend with
encapsulating contact lens material in order to inhibit tearing of
the encapsulating material away from the module.
Microfluidic Module
[0076] FIG. 1 shows a top view of a fluidic module 150, comprising
a central chamber 160 and several peripheral chambers 180,
interconnected via micro-channels 172, upon primary gaze, in
accordance with embodiments.
[0077] In many embodiments, the design comprises a single,
hermetically sealed fluidic module that comprises one or more
separate chambers, interconnected by means of micro-channels,
embedded in a soft contact lens, as shown in FIG. 1.
[0078] In many embodiments, the central chamber 160 is cylinder
shaped with edges that are relatively stiff, its faces being
covered by a relatively flexible distensible membrane. The top and
bottom faces can be circular in shape.
[0079] The central chamber is connected to each of the peripheral
chambers by means of a micro-channel.
[0080] FIGS. 2A-2C show examples of fluidic modules and chambers,
in accordance with embodiments.
[0081] The shape of the peripheral chambers are also cylindrical,
and their top and bottom faces are circular or elongated, as shown
in FIGS. 2A-2C.
[0082] The fluidic module can be located inside the soft contact
lens 100 such that the geometrical center of the lens optic is
co-linear with the geometrical center of the central chamber of the
fluidic module.
[0083] The fluidic module can be filled with a biocompatible fluid
190, preferably of the same refractive index as the material of the
soft contact lens, in the range of 1.44 to 1.55 or about 1.40 to
about 1.55, for example.
[0084] The viscosity of the fluid can be in the range 0.2-2.0
centistokes at 37 C, or in the range of about 0.2 to 5.0
centistokes at 37 C.
[0085] The fluid 190 is preferably a siloxane, a fluorocarbon, an
ester, an ether or a hydrocarbon, or combinations thereof, for
example.
[0086] The membrane is biocompatible, and has an index preferably
substantially the same as the fluid and the contact lens itself, in
the range 1.44-1.55, or within the range from 1.40 to 1.55, for
example.
[0087] The membrane may be of the same thickness throughout, or it
may have a thickness profile, contoured to control its rigidity or
flexibility along the dimensions of the membrane.
[0088] The membrane is preferably a fluorocarbon, a polyester, a
polyurethane, a polyether, a polyimide, a polyamide, an acrylate or
methacrylate ester, or a copolymer bearing these
functionalities.
[0089] The module may comprise on or more of many optically
transmissive materials, such as one or more of a plastic, a
polymer, a thermo plastic, a fluoropolymer a non-reactive
thermoplastic fluoropolymer, or polyvinylidene difluoride
(hereinafter "PVDF"), for example.
[0090] The micro-channels are fabricated from a biocompatible
material, and may be a fluorocarbon, a polyester, a polyimide, a
polyamide, an epoxide, an acrylate or methacrylate ester, or a
hydrocarbon such as polypropylene or polyethylene.
[0091] The walls of the central chamber of the module may either be
composed of the same material as the membrane on the two sides, or
it may be made of a different material.
[0092] The fluidic module 150 can be embedded in the soft contact
lens 100 such that the module is close to the anterior (convex)
surface of the lens.
[0093] Preferably there is a thin layer of contact lens material
above the fluidic module, its thickness being in the range of 5-10
microns.
[0094] Being close to the surface of the contact lens, a change in
curvature of the fluidic module (caused by inflation or deflation
through fluid transfer between the central and peripheral chambers)
causes a corresponding change in the anterior curvature of the soft
contact lens.
[0095] The diameter 161 of the central chamber 160 can be at least
about 3 mm, for example within a range from about 3.0 to 5.0 mm,
such as a range from about 3.0 to about 4.5 mm, for example within
a range from about 4.0-4.5 mm, while the length of the edge can be
about 10-40 microns.
[0096] The thickness of the membranes 162, 166, comprising the top
and the bottom surfaces of the central chamber can be in the range
5-20 microns.
[0097] The thickness of the membrane comprising the edge 164 can be
in the range 10-50 microns.
[0098] The peripheral chambers 180 have a total area of 5.0-8.0
mm.sup.2 and a thickness of 10-30 microns each.
[0099] The total volume of the sealed module can be in the range of
0.15-0.80 mm.sup.3, or 0.15-0.80 microliter, or from about 0.15 to
about 2.50 mm.sup.3 (about 0.15 to about 2.50 microliter), for
example.
[0100] Each micro-channel can be about 10-30 microns in internal
diameter and about 2-5 mm long, or from about 1 to about 5 mm long,
for example.
[0101] The micro-channels may be designed to have an uniform
internal diameter or it may have micro-indentations oriented to
impede flow in one direction in preference to the other.
[0102] The purpose of these indentations can be to modulate the
response time of the onset and removal of the additional plus power
after the down-gaze.
[0103] FIG. 3 shows a top view of the fluidic module, comprising a
central chamber and several peripheral chambers, interconnected via
micro-channels, upon downward gaze, in accordance with
embodiments.
[0104] The mechanism of action involves movement of the scleral
sphere caused by down-gaze typically occurring when the wearer
attempts to read or perform a near vision task.
[0105] The eyeball moves down by about 20 degrees-60 degrees,
depending on the level of down-gaze, causing the corneal surface to
rotate down by about 2.0 mm-6.0 mm
[0106] The peripheral chambers slide under the lower eyelid and can
be compressed, as shown in FIG. 3.
[0107] A 2.0 mm downward movement of the lens positioned on the
cornea will cause partial (30-60%) compression, while a 4.0 mm or
greater eye movement will cause the entire peripheral chamber to be
compressed.
[0108] In many embodiments eyelid caused compression will be able
to expel a fraction (20%-60%) of the fluid in the peripheral
chamber(s) when the totality of peripheral chambers move under the
lower eyelid.
[0109] The fluid moves travels through the micro-channels connected
at the distal end to the central chamber, and increases the
hydrostatic pressure in the central chamber.
[0110] The hydrostatic pressure being equal in all directions,
causes a spherical inflation of the membrane on the top and bottom
faces.
[0111] This inflation may be preferentially directed to the top
surface by using a thicker membrane at the top surface, rendering
it stiffer than the membrane covering the bottom surface of the
central chamber.
[0112] In some embodiments, the hydrostatic pressure may be equal
in all directions, and consequently causes a spherical inflation of
the membrane on the top and bottom faces.
[0113] In many embodiments, the relative extent of inflation of the
top and the bottom faces can be adjusted by adjusting the thickness
of the membranes covering the top and bottom faces and providing an
accommodating module having an appropriate thickness of each of the
top and bottom membranes.
[0114] Similarly, the edge can be rendered less distensible by
using a relatively thick walled membrane for its fabrication.
[0115] In many embodiments, a 2.0 D increase in power can be
achieved by a 5.0-7.0 micron sag height change of the anterior
(top) surface of the central chamber, when the central chamber is
within a range from about 3.0 mm to about 5.0 mm, for example about
4.0 mm in diameter. Alternatively or in combination, a 2.0 D
increase in power can be achieved by a 5.0-15.0 micron sag height
change of the anterior (top) surface of the central chamber, when
the central chamber is within a range from about 3.0 mm to about
5.0 mm, for example about 4.0 mm in diameter.
[0116] This change in curvature can be effected by injection of
fluid of volume equal to 0.10-0.15 microliters. Alternatively or in
combination, the change in curvature can be effected by injection
of fluid of volume within a range from about 0.07 to about 0.21
microliters, for example.
[0117] In many embodiments, the total volume of fluid to be
expelled from the peripheral chambers to the central chamber due to
eyelid pressure can be within a range from about 0.10 to about 0.30
microliters. Alternatively or in combination, the total volume of
fluid to be expelled from the peripheral chambers to the central
chamber due to eyelid pressure can be within a range from about
0.07 to about 0.30 microliters.
[0118] As shown in FIGS. 1-3, the central optical chamber 160
comprising the reservoir is connected to the one or more eyelid
engaging chambers with one or more extensions 170 comprising one or
more channels 172. The one or more eyelid engaging chambers 180 may
comprise a plurality of eyelid engaging chambers, such as chamber
A, chamber B, chamber C and chamber D. A plurality of extensions
comprising a plurality of channels connects the plurality of
chambers to the central optical chamber. The micro-channels extend
between the central optical chamber and each of the plurality of
chambers.
[0119] The plurality of eyelid engaging chambers can be arranged in
one or more of many ways. For example, the eyelid engaging chambers
can be arranged to engage the eyelid sequentially, simultaneously,
incrementally, or in combinations thereof, for example.
[0120] The plurality of eyelid engaging chambers can be arranged to
provide incremental amounts of optical power to the central optical
chamber upon increasing engagement of the lower eyelid with the
plurality of chambers. In many embodiments, a first eyelid engaging
chamber such as chamber B or chamber C engages the eyelid before a
second eyelid engaging chamber such as chamber A or chamber D.
Engagement of the first eyelid engaging chamber can urge a first
amount of fluid into the central optical chamber to provide a first
amount of optical power. Engagement of the second eyelid engaging
chamber can urge a second amount of fluid into the central optical
chamber to provide a second amount of optical power greater than
the first amount of optical power. The first amount of fluid from
the first eyelid engaging chamber can be combined with the second
amount of fluid from the second eyelid engaging chamber to provide
the second amount of optical power greater than the first amount of
optical power, for example. In many embodiments, the first amount
of fluid can be combined with the second amount of fluid within the
central optical chamber to provide the increased optical power.
[0121] In many embodiments, the first chamber comprises a first
plurality of chambers, and the second chamber comprises a second
plurality of chambers, for example. Chambers B and C may comprise a
first plurality of chambers, each contributing an amount of optical
power within a range from about 0.25 Diopters to about 0.75
Diopters, for example. Chambers A and D may comprise a second
plurality of chambers, each contributing an amount of optical power
within a range from about 0.25 Diopters to about 0.75 Diopters, for
example. For example each of chambers A, B, C and D may provide
about 0.5 Diopters of correction, and engagement of chambers B and
C provides about 1 D of additional optical power with a first
position of the lens in relation to the eyelid, and engagement of
chambers A, B, C and D provides about 2 D of additional optical
power with a second position of the eyelid in relation to the
lens.
Manufacturing of the Fluidic Module
[0122] FIG. 4 shows a flow chart of assembly of the fluidic
module.
[0123] The manufacturing process 400 of this fluidic module 150
involves forming the central and the peripheral chambers as well as
the micro-channels separately, then joining them in order to form
the whole module, as shown in FIG. 1.
[0124] Preferably, the peripheral chambers are formed by casting,
injection molding or blow molding.
[0125] Thermoplastics, preferably partially crystalline
thermoplastics such as polycarbonate, polypropylene, polyethylene,
polyethers, polyamides, polyimides, polyfluorocarbons such as
polyvinylidene difluoride (hereinafter "PVDF"), polyvinylidene
fluoride, for example commercially available Tyvek.TM. or
Kynar.TM., may be used to injection mold or blow mold the
chambers.
[0126] These materials have superior toughness, and many of them
are biocompatible.
[0127] In many embodiments, the following steps are used for
fabrication of the central optical chamber 160.
[0128] In many embodiments, the edge wall is formed first at a step
440, using a mandrel or a cylindrical mold to wrap around a thin
film cut to shape at a step 442. For example, a piece of a
thermoplastic cut into a strip 6.3-6.5 mm long, 20 microns wide and
5 microns in thickness is cut from a roll of this material, using a
water jet or a picosecond pulsed laser, for example.
[0129] In many embodiments, this strip 444 is wrapped around a
rigid mandrel of diameter 4.0 mm, and it's the free edges that
overlap over a distance of 0.1-0.3 mm are sealed by a heat sealing
or laser welding process at a step 446.
[0130] The mandrel may be made of a stiff, for example relatively
rigid material, capable of withstanding relatively high
temperatures, and should have a relatively low thermal expansion
coefficient such as a high melting plastic, e.g., an aromatic
polyimide, a ceramic or a metal.
[0131] In many embodiments, the cylindrical shape is removed from
the mandrel after the edges have been joined, for example.
[0132] In many embodiments, the shape is placed on a flat, rigid
substrate over a flat end piece made of a thermoplastic or
thermoset material whose diameter is matched to the diameter of the
cylinder.
[0133] In many embodiments, the edge is sealed by a laser welding
or a heat sealing process, preferably acting through the rigid
substrate or platform supporting the end piece.
[0134] The platform also functions as a heat sink and minimizes
heat diffusion up into the wall or across the surface of the end
piece.
[0135] Precise control of temperature rise away from the joint can
be helpful in order to minimize heat distortion.
[0136] In many embodiments, once the end piece has been sealed to
the edge of the cylinder, the piece is inverted, placed over a
second end piece, then the sealing process is repeated.
[0137] In many embodiments, the micro-channels 170 are fabricated
at a step 450 from thin sheets of a thermoplastic such as
polyethylene, polypropylene, polyvinylidene difluoride (PVDF),
Tedar.TM., Kynar.TM., Viton.TM., or other heat sealable or weldable
materials, for example.
[0138] In many embodiments, the preferred process at a step is
similar to the one used to fabricate the edge member of the central
chamber 160, as described above.
[0139] At a step 452 strips 454 can be cut as described herein.
[0140] At a step 456 the strips of material can be sealed as
described herein to form the extensions 170 comprising the channels
as described herein.
[0141] At a step 410, the top surface of the central optical
chamber 150 is made. At a step 412 PVDF sheet is cut as described
herein to make the circular membrane 414. At a step 416, the
circular membrane 414 is sealed on the upper rim of the extension
to form upper membrane 162 of the central optical chamber.
[0142] At a step 420, the bottom surface of the central optical
chamber 150 is made. At a step 422 PVDF sheet is cut as described
herein to make the circular membrane 424. At a step 426, the
circular membrane 424 is sealed as described herein on the upper
rim of the support to form upper membrane 162 of the central
optical chamber.
[0143] At a step 430, the peripheral chamber is formed by blow
molding. At a step 432 the peripheral chamber is provided for
assembly and may be sealed as described herein.
[0144] At a step 460 components of the module are assembled to form
the module 150.
[0145] The components assembled in order to manufacture module 150
comprise a top surface of the central chamber 418, a bottom surface
of the central chamber 428, a peripheral chamber 434, walls of the
central chamber 448 and the micro-channel 458.
[0146] In many embodiments, the tubes forming the micro-channels
458 are next sealed on to the edges of the central chamber 448 and
the peripheral chamber 180, as shown in FIG. 1.
[0147] In many embodiments, the process provides an initial step
sealing the tubes edgewise onto the wall of the edges, so that a
fluid tight seal is formed 360 degrees around the circumference of
the micro-channels.
[0148] In many embodiments, a metal insert is then used to
penetrate the wall of the edges of the central chamber and the
peripheral chamber(s) in order to open a fluid path. This path is
fully enlarged so that is equal to the internal diameter of the
micro-channel.
[0149] In many embodiments, an inlet and an outlet port are then
affixed to the wall of the peripheral chamber(s), using a process
similar to the one used above.
[0150] In many embodiments, the inlet and outlet ports are tubes
similar in diameter, wall thickness and length as the
micro-channels, and micro-channel pieces fabricated as above may be
used as inlet and outlet ports.
[0151] In many embodiments, preferably, the inlet port is attached
to the peripheral chamber and the outlet port is attached to the
central chamber.
[0152] FIG. 5 shows a method 500 of filling and sealing of the
fluidic module. In many embodiments, the assembled module is then
filled with fluid, as follows.
[0153] The fluid 190 to be used to fill the module is degassed by
placing it in a closed container with an opening, closing the
opening with a valve, cooling the fluid down to a temperature at
which the fluid freezes or to -100 C whichever is greater, then
pulling vacuum through this opening so as to expel all air from the
space above the fluid in the container.
[0154] The vacuum is shut off, the fluid is warmed to room
temperature, then it is cooled again, before reapplying vacuum.
[0155] This process is repeated until a pressure gauge, connected
to the fluid container registers no change in pressure upon
application of vacuum to the container containing the fluid at a
low temperature.
[0156] In many embodiments, a consideration is not to apply vacuum
to the container when the fluid is at room temperature, in order to
avoid evaporative losses of the fluid.
[0157] A gas tight syringe is inserted into the container, a
quantity of fluid is drawn into the syringe, the tip of the syringe
inserted into the inlet port affixed to the peripheral chamber.
[0158] An outlet tube, preferably made of metal is affixed to the
outlet port.
[0159] The module is positioned such that the fluid inlet port is
at the bottom and the outlet port is at the top.
[0160] Vacuum is pulled through the outlet tube, as the syringe is
driven to inject fluid through the inlet tube.
[0161] Fluid injection is topped when the module is filled with
fluid, and the fluid level reaches the outlet tube.
[0162] The inlet and the outlet tubes are then sealed off close to
the edge of the wall of the chambers, leaving approximately 0.05 to
0.1 mm clearance.
[0163] The sealing process may involve application of heat, or a
laser beam, for example.
[0164] The foregoing is given as an example, in accordance with
embodiments, and is not intended to limit the described
manufacturing and assembly process in any way.
Embedding the Microfluidic Module in a Soft Contact Lens Body
[0165] FIG. 6 shows a method 600 of encapsulating a module 150
within contact lens material 110 to form an accommodating contact
lens. While the method 600 can be performed in one or more of many
ways, in many embodiments method 600 comprises modification of
conventional process of molding and forming a soft contact lens
made of a hydrophilic monomer or a silicone hydrogel to add the
inclusion of a fluidic module, fabricated as shown in FIG. 5 and as
described herein, in accordance with embodiments;
[0166] In many embodiments, after assembly, the fluidic module
passes through an inspection station at a step 645 that may be
automated for high volume production that comprises a vision system
to check dimensions and seal integrity and an optical probe to test
the optical properties of the central chamber, when the peripheral
chamber is compressed.
[0167] In many embodiments, the module is then placed in a tray
designed for a pick and place robot at a step 610, and delivered to
the contact lens manufacturing line that may be automated for high
volume production.
[0168] At a step 620, a degassed monomer can be provided.
[0169] At a step 630, molds are provided.
[0170] At a step 632, bottom molds are placed in trays.
[0171] At a step 634, bottom molds are placed on an automated
track.
[0172] At a step 636, bottom molds are placed with monomer.
[0173] At a step 612, the module 150 is picked up and placed with a
monomer.
[0174] At a step 640, top molds are placed in trays.
[0175] At a step 642, the top molds placed in the trays are picked
up and placed with a robot.
[0176] At a step 638, bottom molds with monomer and module in place
receive the top molds.
[0177] At a step 650, the assembly is molded on the track.
[0178] At a step 652, UV radiation or heat is applied to mold the
assembly on the track.
[0179] At a step 654, the assembly is placed in a demolding
bath.
[0180] At a step 656, the accommodating contact lenses are
inspected with a vision system. In many embodiments, the optical
properties of the module such as optical power and change in
optical power are determined prior to placement in the mold in
order to provide a functional accommodating contact lens to the eye
of the subject.
[0181] At a step 658, the accommodating contact lenses are
packaged.
[0182] At a step 659, the molds are cleaned and returned to
inventory.
[0183] In many embodiments, the contact lens is typically made of a
hydrophilic monomer or a silicone hydrogel material as described
herein.
[0184] The lens may be formed, by way of example only, by cast
polymerizing a monomer mixture comprising the monomer, an
ultraviolet or thermal polymerization initiator and other additives
such as a UV blocking agent or an antioxidant, for example.
[0185] In many embodiments, the cast molding process is generally
performed by creating a cavity formed by two molds, filling this
cavity (mold cavity) with a layer of the monomer formulation, then
applying energy, that may be ultraviolet radiation, heat,
ultrasonic energy, microwave energy, or the like to trigger the
polymerization process by activating the polymerization
initiator.
[0186] In many embodiments, the monomer formulation is cured by
application of energy in the form of UV radiation, since a UV
curing process allows better control of cure temperature and
completes the cure in a shorter time.
[0187] In many embodiments, the UV radiation that is applied to
initiate the curing process is in the range of 300 nm to 500
nm.
[0188] More preferably, the wavelength range is 310 nm to 450
nm.
[0189] In many embodiments, the tray comprising multiple mold
assemblies, each consisting of a lower mold, a layer of monomer,
the fluidic module immersed in monomer, and a top mold, is moved at
a slow uniform speed along a track through a tunnel illuminated
with UV radiation, provided from a bank of UV light sources placed
either under and/or over the track
[0190] In many embodiments, typically, the UV radiation induced
cure process is completed within 30-600 seconds.
[0191] In embodiments using UV curing process, the mold through
which UV radiation is transmitted is transparent to UV in the
wavelength range to activate the UV initiator, typically 310 nm to
450 nm.
[0192] Cure process initiated by other types of energy, e.g., heat
may be provided with a substantially longer cure period.
[0193] In many embodiments, the monomer is cured as in a
conventional line, although it is possible that the cure time may
have to be increased in order to allow of the UV blocking
properties of the fluidic module.
[0194] The UV radiation may be applied from the top and the bottom
in order to fully cure the monomer, forming the contact lens.
[0195] In many embodiments, the steps involving loading of the top
and bottom molds in trays that move along separate paths, the
delivery of the monomer into the bowl of the second mold, the
placement of the upper mold into the layer of the monomer allowing
it to spread and form a continuous layer of desired thickness are
all automated in a high volume production line.
[0196] FIG. 6 shows how the conventional process of molding and
forming a soft contact lens made of a hydrophilic monomer or a
silicone hydrogel may be modified to add the inclusion of a fluidic
module, fabricated as shown in FIG. 5.
[0197] In many embodiments, the sealed module is added by means of
a pick and place robot to the lower mold after the monomer has been
injected, so that the optical center of the central chamber is
aligned with the optical center of the mold.
[0198] In many embodiments, the monomer comprises, for example
consists of, hydrophilic components capable of undergoing radical
induced addition polymerization, such as acrylates and
methacrylates, as well as certain allyl, vinyl or styrenic
compounds.
[0199] A vision system may be used to check the alignment of the
fluidic module delivered into the pool of the monomer in the lower
mold.
[0200] Although reference is made to a monomer, a person of
ordinary skill in the art will recognize that one or more of many
precursor components can be used to form the polymer in accordance
with the teachings described herein, such as one or more of a
monomer, an oligomer, a pre-polymer, or a composition comprising
mixtures of reactive polymers with un-reacted monomers, for
example.
[0201] One or more of the steps of FIG. 6 is suitable for
combination in accordance with embodiments disclosed herein.
[0202] In manufacturing an accommodating soft contact lens (ACL)
incorporating a fluidic module embedded at or near the optical
center of the lens, the seamless integration of the module in the
lens body is generally desired. For example, if the ACL is formed
by cast molding a relatively hydrophilic monomer formulation in a
mold cavity in which the module is pre-positioned at the correct
location before the mold cavity is sealed and curing commences, it
may be helpful to ensure that the cure induced shrinkage forces do
not cause the fluidic module to be deformed. The hydration process
that follows the curing step may also cause the module to collapse
at certain points, which may lead the fluid to pool at other parts
of the module, or make it lose adhesion to the lens material, which
may cause formation of bubbles at the interface of the module
membrane and the lens body.
[0203] It is therefore desirable to provide a more controlled
encapsulation process of the fluidic module into the lens body. It
is also desirable to provide a positioning and fixing process for
the module into the lens body such that the module is not displaced
during subsequent processing steps.
[0204] As used herein, the word "cup" refers to a mold without an
optical surface, as commonly used in the contact lens manufacturing
industry. A cup, as used herein, denotes a container having a floor
and walls, that is used to contain a fluid monomer. A cup may
comprise a material that is transparent to radiation used to cure
the monomer, or is able to withstand the curing temperature for
several hours, for example up to 48 hours.
[0205] FIGS. 7-13 illustrate a molding and machining process which
when used in tandem can form the ACL with an embedded module.
[0206] FIG. 7 shows a polystyrene (PS) mold 2000 that may be used
to form a semi-finished button. The PS mold 2000 may form the
concave surface 1000 of the ACL. The PS mold 2000 may be used to
cast a semi-finished button from the monomer formulation by
attaching a cup 3000 to the PS mold 2000 as shown in FIG. 8,
thereby forming a mold cavity 3500 and curing the monomer
formulation inside this cavity. The button may be referred to as
semi-finished because one of its surfaces may be molded to the
final finish, while the other surface is machined in subsequent
steps. The PS mold 2000 may have a fixture that can be used to
attach the anterior cup 3000 for a second molding step as shown in
FIG. 8. This cup 3000 may be removed after the casting process is
complete.
[0207] The polystyrene mold 2000 may form the concave surface 1000
of the lens. As shown in FIG. 9, the semi-finished button 5000 may
be diamond turned to form the intermediate surface 4000. The PS
mold 2000 may comprise an adapter element 2100 centered at the base
of the mold; the adapter element 2100 can be used for capturing the
part into the collet of the lathe or the mill. The center line of
the rod feature or adapter element 2100 at the back of the PS mold
2000 (see FIG. 7) may form the geometrical center of the ACL.
[0208] After the intermediate surface 4000 has been formed, the
part may then be transferred to a precision milling machine to
create a bed 4100 for the fluidic module 150 as shown in FIG. 10.
The module 150 can be made to adhere to the intermediate surface
4000 by using a drop of the monomer formulation that is partially
cured as an adhesive.
[0209] A second cup 6000 may now attached to the PS mold 2000,
forming a molding cavity 6500 between the intermediate surface 4000
and the inner surface 6100 of the second cup. This space can be
filled with the monomer mixture, vacuum can be applied to remove
bubbles, and the monomer can be cured to form a second
semi-finished form of the button 5000, as shown in FIG. 11.
[0210] The casting cup can then be removed, and the cured polymer
110 can be precision machined in order to form the final lens 100
and its anterior surface 7000 as shown in FIG. 12. The machining
process may form the optical zone for optical power and optical
center, the peripheral zone for stabilization, and the edge for
comfort and fit. The lens may then be hydrated before being
inspected and packaged prior to sterilization.
[0211] FIG. 13 shows a process 1300 of molding and forming a soft
contact lens comprising a fluidic module, fabricated as shown in
FIGS. 7-12, in accordance with embodiments. In step 1310, a
polystyrene mold having a concave surface is provided. In step
1315, a first cup is attached to the mold, and a monomer
formulation is added to the mold cavity and cured to form the
intermediate surface of the ACL. In step 1320, the intermediate
surface is machined to create a bed for the fluidic module, and the
module is adhered onto the bed. In step 1325, a second cup is
attached to the mold, and the monomer formulation is added to the
mold cavity and cured to form the semi-finished anterior surface of
the ACL. In step 1330, the semi-finished anterior surface is
machined to form the finished anterior surface. In step 1335, the
ACL is removed from the mold, extracted in water to remove diluent,
then hydrated in water or physiological saline. In step 1340, the
ACL is inspected, packaged, and sterilized.
[0212] FIG. 13 shows a method of molding and forming a soft contact
lens in accordance with some embodiments. A person of ordinary
skill in the art will recognize many adaptations and variations in
accordance with the embodiments disclosed herein. For example some
of the steps can be deleted; additional steps can be performed; the
order of the steps can be changed; some of the steps comprise
sub-steps; some of the steps can be repeated and some of the steps
may comprise one or more steps of other methods as disclosed
herein.
[0213] FIGS. 14-23 illustrate another molding and machining process
which when used in tandem can form the ACL with an embedded
module.
[0214] In the process of FIGS. 14-23, the two lens surfaces may be
formed by a precision machining process. The process may begin with
a casting of a button formed by curing the monomer formulation in a
non-optical mold (called a casting cup), which may be made of a
thermoplastic such as polymethyl methacrylate (PMMA). FIG. 14 shows
an empty casting cup 8000. This cup may comprise an adapter element
8100 (e.g., on the bottom surface opposite the cavity of the
casting cup) to capture the part by a collet of a precision lathe
or a mill.
[0215] FIG. 15 shows the casting cup 8000 with the cured monomer
formulation 110 forming a button 9000. As shown in FIG. 16, the
button 9000 can be machined down to form an intermediate surface
9100 that may function as a substrate for the fluidic module. A
protrusion 9200, in the form of a protruding rim, may be machined
at the edge of the intermediate surface, so as to provide an edge
to the lens. For example, the protrusion may be a rim with a
diameter of about 14 mm, defining the edge of a correspondingly
sized contact lens. The protrusion can provide a reference point
for proper alignment throughout the manufacturing process, by
allowing the edge of the lens to remain visible. For example, the
protrusion can help the fluidic module to be properly centered when
being placed.
[0216] The intermediate surface 9100 may be further milled in order
to create a bed 9300 for the module 150, as shown in FIG. 17. The
bed provides for precise alignment, by making it difficult for the
seated module to move outside of the bed throughout the
manufacturing process. The machined bed may further comprise a side
tab 9350, which can provide a reference for determining the correct
side alignment of the module during placement. The bed can be
moistened with a drop of an adhesive that matches the refractive
index of the monomer formulation. For example, the monomer
formulation itself may be partially cured, for example by exposure
to UV radiation for a few seconds, then placed on the bed of the
module. The module can be placed over the adhesive onto the bed to
ensure adhesion to the intermediate surface as shown in FIG. 17.
The module may be positioned manually, by centering the module
under an operating microscope, adjusting the angle as
appropriate.
[0217] The cup 8000 may then be attached to a second casting cup,
and additional monomer formulation may be injected into the mold
cavity formed by the two cups. The cured monomer formulation 110
can form a button 9000 with an embedded fluidic module 150, as
shown in FIG. 18.
[0218] The second cup can be removed, and the first casting cup
8000 may then be mounted on a collet of a precision diamond turning
machine, holding it using the end rod or adapter element 8100. The
surface of the button 9000 can be machined to form the first
finished, concave surface 9400 of the lens as shown in FIG. 19.
[0219] The casting cup 8000 containing the semi-finished button
9000 may then be attached to a block 8500 having a domed protrusion
8510 to engage the concave, first finished surface 9400 of the
lens, as shown in FIGS. 20 and 21. The concave surface of the lens
may be blocked using an adhesive 8520 such as water soluble wax or
other blocking agent, then engaged with the domed protrusion of the
block, preferably with the block 8500 and the first casting cup
8000 centered to within 10 microns.
[0220] The block 8500 also comprises an adapter element 8600 that
can be used for capturing the part into the collet of the lathe or
the mill. Once attached to the casting cup 8000 containing the
semi-finished button 9000, the block can then be mounted on a
precision lathe, to cut away the PMMA cup 8000 and form the second
or the convex (anterior) surface 9500 of the lens as shown in FIG.
22.
[0221] The machining process may form the optical zone 200 for
optical power and optical center, the peripheral zone 210 for
stabilization, and the edge 220 for comfort and fit. The machining
process may provide the generation of non-radially symmetric
features as when creating a toric surface or stabilization
mechanisms on the lens surface.
[0222] The lens 100, now comprising two finished surfaces 9400 and
9500 as shown in FIG. 22, is then deblocked to remove from the
block 8500 and to remove the blocking agent 8520, for example by
using water to dissolve the blocking wax. The final lens 100, as
shown in FIG. 23, is then extracted typically for several hours to
remove the diluent, and replaced in water or physiological
saline.
[0223] The lens can then be inspected and packaged for
sterilization.
[0224] FIG. 24 shows a process 2400 of molding and forming a soft
contact lens comprising a fluidic module, fabricated as shown in
FIGS. 14-23, in accordance with embodiments. In step 2410, a
casting cup having an adapter element is provided. In step 2415,
the cup is filled with a monomer formulation and cured to form a
button. In step 2420, the button is machined to create an
intermediate surface, comprising a bed for the fluidic module and a
protruding rim that defines the edge of the lens. In step 2425, the
module is attached to the intermediate surface by adhering the
module to the bed. In step 2430, a second cup is attached to the
casting cup, and the mold cavity is filled with a monomer
formulation and cured to form a button with the embedded fluidic
module. In step 2435, the button surface is machined to form the
concave (posterior) surface of the lens. In step 2440, the casting
cup containing the button is attached to a block at the concave
surface of the lens, where the concave surface of the lens is
blocked with a blocking agent. In step 2445, the casting cup and
the cured monomer formulation button is machined away to form the
convex (anterior) surface of the lens. In step 2450, the
accommodating soft contact lens (ACL) with the embedded fluidic
module is removed from the block, extracted in water to remove the
diluent, and hydrated in water or physiological saline. In step
2455, the ACL is inspected, packaged, and sterilized.
[0225] FIG. 24 shows a method of molding and forming a soft contact
lens in accordance with some embodiments. A person of ordinary
skill in the art will recognize many adaptations and variations in
accordance with the embodiments disclosed herein. For example some
of the steps can be deleted; additional steps can be performed; the
order of the steps can be changed; some of the steps comprise
sub-steps; some of the steps can be repeated and some of the steps
may comprise one or more steps of other methods as disclosed
herein.
Formulating the Soft Contact Lens Material Precursor
[0226] As described herein, in manufacturing an accommodating soft
contact lens (ACL) incorporating a fluidic module embedded at or
near the optical center of the lens, the seamless integration of
the module in the lens body is generally desired. For example, if
the ACL is formed by cast molding a relatively hydrophilic monomer
formulation in a mold cavity in which the module is pre-positioned
at the correct location before the mold cavity is sealed and curing
commences, it may be helpful to ensure that the cure induced
shrinkage forces do not cause the fluidic module to be deformed.
The hydration process that follows the curing step may also
configured to inhibit changes in the volume of the cured contact
lens covering material. In many embodiments, a lens material is
provided that may be formed from a monomer formulation that is
designed to provide good integration with the embedded fluidic
module.
[0227] In many embodiments, the monomer formulation is chosen to
have physical and chemical properties desirable for use as a soft
contact lens. For example, the formulation can compromise a monomer
that is optically transparent and have a refractive index in the
range 1.41-1.43 measured at 536 nm. The monomer formulation can
form a lens that, when hydrated, is wettable, as measured by a
contact angle of 60 degrees or less. Preferably, the monomer has
good oxygen permeability, measured as Dk/I in the range 30-50
barrers. The monomer may have a glass transition temperature in the
range 0-20.degree. C., and the modulus of the polymer may be in the
range 0.3-1.5 MPa. In many embodiments, the monomer formulation is
chosen to have physical and chemical properties that match at least
some of the properties of the material comprising the module.
[0228] In many embodiments, the formulation may have reduced
shrinkage during curing, such that the curing of the soft contact
lens material does not cause the deformation of the fluidic module.
For example, the formulation may comprise a monomer that is curable
to form the lens at a temperature not exceeding 50.degree. C., and
has a water content in the range 25-50%. Preferably, the monomer
has a cure shrinkage less than or equal to 5% by volume.
[0229] In many embodiments, the formulation is designed to have
reduced water expansion when the soft contact lens is hydrated with
water or saline subsequent to the formation of the lens. For
example, the monomer can be premixed with a diluent, chosen such
that the diluent can be replaced by water subsequent to the
formation of the lens without causing a significant change in
volume of the lens. Preferably, the water expansion of the formed
lens upon replacement of the diluent is water is less than 5% by
volume.
[0230] A diluent for the monomer formulation may comprise a mix of
two or more components, chosen to reduce cure shrinkage and water
expansion of the cured monomer. While the diluent does not
chemically participate in the curing reaction, it affects the rates
of the reactions by altering the mole fractions of each reactive
constituent and the overall viscosity of the material. The diluent
may comprise a high molecular weight component with relatively high
density and viscosity, such as polyethylene glycol, and a low
molecular weight component with relatively low density and
viscosity, such as isopropanol. High molecular weight components in
the diluent can help to inhibit cure shrinkage, by increasing the
viscosity of the diluent. Low molecular weight components in the
diluent can help improve the hydration of the contact lens when
placed in water, and can help improve diluent extraction from the
cured monomer, thereby improving the biocompatibility of the
contact lens. Preferably, the mix of components is selected such
that the molar volume of the diluent is equal to or close to the
molar volume of water, in order to minimize the expansion of the
cured monomer when the diluent is replaced with water.
[0231] In many embodiments, the monomer formulation comprises a
mixture of hydrophilic acrylates and methacrylates, a photochemical
polymerization initiator, and a diluent, selected so as to have a
high but controlled rate of initiation and polymerization. This
monomer formulation may have a final glass transition temperature
of the polymerization product of less than 25.degree. C., so that
the cure process can be completed at or near room temperature and
provides a cure or post-cure temperature no higher than 50.degree.
C.
[0232] FIG. 25 shows a table of some exemplary materials that the
monomer formulation may comprise, in accordance with embodiments.
The formulation may comprise one or more of many components,
including mono-functional monomers, multi-functional monomers,
cross-linkers, diluents, and photo-initiators. For example, a
formulation may compromise a mixture of hydroxyethyl methacrylate
(10-30% w/w) and methoxyethyl methacrylate (10-20% w/w), with a
smaller proportion of a more hydrophilic monomer such as
polyoxymethylene diacrylate or glycerol monomethacrylate (0-15%
w/w), a highly hydrophilic monomer with a slower curing rate such
as N-vinyl pyrollidone (0-15% w/w), a cross-linker such as
trimethylolpropane triacrylate or trimethylol propane
trimethacrylate, or ethylene glycol dimethacrylate or N,N' diethyl
bisacrylamide (1-5% w/w), a photo-initiator such as diethoxy
acetophenone or diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide
(1-3% w/w), and a diluent such as polyethylene glycol of molecular
weight 600-4,500 Da (20-35% w/w).
[0233] To prepare the monomer formulation for manufacturing a
contact lens, monomer components may first be purified to remove
polymerization inhibitors, by one of many methods well-known in the
art such as fractional distillation, spinning band distillation,
and preparative liquid chromatography. The formulation comprising
the mixed monomers may then be degassed to remove dissolved oxygen,
then molded to shape the body of the contact lens as described
herein. Subsequently, the monomer formulation may be cured by one
of many known methods, such as photo-curing by exposure to
ultraviolet radiation at a modest temperature. The formed contact
lens may be extracted to remove the diluent, then replaced in water
or physiological saline for sterilization and distribution.
[0234] While preferred embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
invention. It should be understood that various alternatives to the
embodiments of the invention described herein may be employed in
practicing the invention. It is intended that the following claims
define the scope of the invention and that methods and structures
within the scope of these claims and their equivalents be covered
thereby.
* * * * *