U.S. patent application number 11/415619 was filed with the patent office on 2006-09-07 for hybrid contact lens system and method.
Invention is credited to Barry Chen, Ali Dahi, Jerome Legerton.
Application Number | 20060197909 11/415619 |
Document ID | / |
Family ID | 31978645 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060197909 |
Kind Code |
A1 |
Legerton; Jerome ; et
al. |
September 7, 2006 |
Hybrid contact lens system and method
Abstract
A hybrid hard-soft contact lens is provided. Several embodiments
of the invention include methods of coupling the hard and soft
sections of the contact lens. Other embodiments of the invention
include contact lens materials and coatings that increase oxygen
transmission though the lens. Yet other embodiments of the
invention are directed to cost-effective manufacturing methods of a
hybrid hard-soft contact lens. This Abstract is provided for the
sole purpose of complying with the Abstract requirement rules that
allow a reader to quickly ascertain the subject matter of the
disclosure contained herein. This Abstract is submitted with the
explicit understanding that it will not be used to interpret or to
limit the scope or the meaning of the claims.
Inventors: |
Legerton; Jerome; (San
Diego, CA) ; Chen; Barry; (San Diego, CA) ;
Dahi; Ali; (Carlsbad, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
31978645 |
Appl. No.: |
11/415619 |
Filed: |
May 1, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10657061 |
Sep 5, 2003 |
|
|
|
11415619 |
May 1, 2006 |
|
|
|
60408618 |
Sep 6, 2002 |
|
|
|
Current U.S.
Class: |
351/159.74 |
Current CPC
Class: |
G02B 1/043 20130101;
B29D 11/00057 20130101; G02C 7/04 20130101; B29D 11/00048 20130101;
G02C 7/021 20130101; B29D 11/0048 20130101; G02C 7/049
20130101 |
Class at
Publication: |
351/160.00R |
International
Class: |
G02C 7/04 20060101
G02C007/04 |
Claims
1-43. (canceled)
44. A method of prescribing a hybrid contact lens, the method
comprising the steps of: providing a contact lens that approximates
a shape of an eye; placing the contact lens on the eye; determining
a direction of a light ray exiting the contact lens; and adjusting
the contact lens so that the light ray exists the contact lens
substantially parallel to a visual axis.
45. The method of claim 44, wherein the step of adjusting the
contact lens so that the light ray exits the contact lens
substantially parallel to the visual axis comprises the steps of:
adjusting a slope of the contact lens; or adjusting a thickness of
the contact lens.
46. The method of claim 44, wherein the contact lens is adjusted to
provide a visual light spectrum wavelength that has substantially
equal areas under a photopic response curve.
47. The method of claim 44, wherein the contact lens is adjusted by
the steps of: multiplying a contact lens light transmission
characteristic by a photopic eye response so that the visible light
exiting the contact lens has substantially equal areas under a
photopic response curve.
Description
[0001] Priority is claimed to U.S. Provisional Application Ser. No.
60/408,618, filed Sep. 6, 2002, titled "Hybrid Contact Lens System
and Method," which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention generally relates to contact lenses.
More particularly, the invention concerns a hybrid hard-soft
contact lens.
BACKGROUND OF THE INVENTION
[0003] Vision correction is on the verge of a revolution. New
technologies to measure the aberrations or distortions in the
optics of the eye will soon be available to the public. These new
wavefront measurement techniques such as Shack-Hartmann wavefront
sensing or Talbot Interferometry can precisely measure the eye's
aberrations so that vision may be corrected up to 20/10. Wavefront
sensing is the method for rapidly, and very accurately, assessing
the aberrations in an individual's eye to create a customized
prescription for correction.
[0004] However, once the eye's aberrations have been measured,
either by conventional methods or by wavefront sensing, these
measurements must then be transferred into a vision correction
system, such as eye surgery, spectacles, or contact lenses. Recent
advances in laser refractive surgery techniques such as LASIK and
photorefractive keratectomy, as well as improvements in spectacle
lens manufacturing now enable the creation of highly accurate
corrective prescriptions for individuals.
[0005] However, this is not the case with contact lenses. Popular
soft contact lenses cannot achieve the same result as spectacles or
laser refractive surgery because of dimensional variations in
fabrication. Hard contact lenses, which may provide the platform to
achieve the results of spectacles, are not as comfortable as soft
contacts and lack the necessary positional stability on the
eye.
[0006] Therefore, there exists a need for a hybrid hard-soft
contact lens that can provide a platform for a corrective
prescription and also provide the comfort of soft contact
lenses.
SUMMARY OF THE INVENTION
[0007] A hybrid hard-soft contact lens is provided. Several
embodiments of the invention include methods of coupling the hard
section of the lens to the soft section of the lens. Other
embodiments of the invention include contact lens materials that
increase oxygen transmission though the lens. Yet other embodiments
of the invention are directed to cost-effective manufacturing
methods of a hybrid hard-soft contact lens.
[0008] These and other features and advantages of the present
invention will be appreciated from review of the following detailed
description of the invention, along with the accompanying figures
in which like reference numerals refer to like parts
throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a front view of a manufacturing step used to
construct a hybrid hard-soft contact lens of the present
invention;
[0010] FIG. 2. is a front view of a contact lens blank after the
manufacturing step illustrated in FIG. 1;
[0011] FIG. 3 is a front view of another manufacturing step used to
construct a hybrid hard-soft contact lens of the present
invention;
[0012] FIG. 4 illustrates another manufacturing step used to
construct a hybrid hard-soft contact lens of the present
invention;
[0013] FIG. 5 illustrates an alternative manufacturing method of
constructing a hybrid hard-soft contact lens of the present
invention;
[0014] FIG. 6 illustrates several embodiments of interface
geometries between a hard section and soft section of a hybrid
hard-soft contact lens constructed according to the present
invention;
[0015] FIG. 6A illustrates a preferred embodiment of an interface
geometry between a hard section and soft section of a hybrid
hard-soft contact lens constructed according to the present
invention;
[0016] FIG. 7 is an illustration of a contact lens, several eye
components and visible light rays exiting the eye-contact lens
system;
[0017] FIG. 8 is another illustration of a contact lens, eye
components and visible light rays, showing the tendency for
different colored light rays to exit the eye at different
angles;
[0018] FIG. 9 illustrates a hypothetical uniform eye response to
the visible light spectrum;
[0019] FIG. 10 illustrates a photopic eye response to the visible
light spectrum; and
[0020] FIG. 11 illustrates one idealized net wavelength response
for a contact lens constructed according to the present
invention.
[0021] It will be recognized that some or all of the Figures are
schematic representations for purposes of illustration and do not
necessarily depict the actual relative sizes or locations of the
elements shown.
DETAILED DESCRIPTION OF THE INVENTION
[0022] In the following paragraphs, the present invention will be
described in detail by way of example with reference to the
attached drawings. Throughout this description, the preferred
embodiment and examples shown should be considered as exemplars,
rather than as limitations on the present invention. As used
herein, the "present invention" refers to any one of the
embodiments of the invention described herein, and any equivalents.
Furthermore, reference to various feature(s) of the "present
invention" throughout this document does not mean that all claimed
embodiments or methods must include the referenced feature(s).
[0023] The present invention is based on a hybrid contact lens
platform that offers the benefits, without the disadvantages, of
both soft and gas permeable contact lenses--comfort, health,
stability, superior optics and durability. The features of the
present invention include lens chemistry, manufacturing processes,
optical design and prescribing and fitting processes. One feature
of the manufacturing processes and optical design elements is the
ability to make quarter wavelength customization in order to
correct for the higher order refractive aberrations that limit
one's ability to see better than 20/20.
[0024] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as is commonly understood by one
of skill in the art to which this invention belongs. In event the
definition herein is not consistent with definitions elsewhere, the
definitions set forth herein will control. As used herein, "hybrid"
refers to a type of contact lens that includes both hard and soft
lens elements.
[0025] One embodiment of the present invention will correct normal
ametropic errors (myopia, hyperopia and astigmatism) to a higher
degree of visual performance than conventional contact lenses.
Another embodiment of the present invention will correct for the
wavefront-guided higher order aberrations and will create a new
contact lens category, providing "super vision" for those whose
visual requirements demand better than 20/20 acuity. Yet another
embodiment of the present invention will correct for presbyopia,
the gradually increasing inability to focus at close distances that
usually begins after age 40. Other embodiments of the present
invention may include contact lenses that incorporate several, or
all of the above-described features.
[0026] Another embodiment of the present invention is a hybrid lens
that combines the optical clarity, stability and durability of a
gas permeable lens with the comfort of a soft contact lens. This
hybrid lens has a gas permeable center chemically bonded to a soft
outer skirt. The center is highly oxygen permeable, which is
important to maintaining corneal health. One of the manufacturing
processes of the present invention enables this gas permeable
center to be lathed to quarter wavelength precision, allowing
corrections of wavefront-guided higher order refractive aberrations
and providing visual performance better than 20/20.
[0027] Yet another embodiment hybrid contact lens of the present
invention has a soft outer skirt with a radius of curvature greater
than the base curve of the oxygen permeable center, which is
suspended on the soft skirt, thus creating a lighter touch above
the corneal apex. One feature of this embodiment is that the eyelid
force of normal blinking creates a peristaltic-like pump that
exchanges the tears under the lens, contributing to overall
comfort, and eliminating dryness, the most frequent complaint of
contact lens wearers. Another feature of this embodiment is that
the tear layer under the lens is not only important for comfort and
health, but it has optical correction qualities as well. A layer of
tears retained behind the base curve of the gas permeable lens of
the present invention may correct corneal astigmatism by up to
about ten diopters. Thus, a hybrid contact lens constructed
according to the present invention creates a superior astigmatism
correcting capability that does not rely on orientation and
positioning, as do soft contact lenses. Another embodiment of the
present invention comprises a hybrid lens with a substantially
rigid center that is chemically bonded to a softer outer skirt. One
embodiment of the outer skirt is comprised of a modified HEMA
(poly-2-hydroxyethyl-methacrylate) material. The center is a
substantially rigid gas permeable-type with a gas permeability DK
value greater than 30. A preferred embodiment center would have a
gas permeability DK value of about 150. However, other embodiments
may have a gas permeability DK value that may range between about
30 to about 250. In a preferred embodiment of the present
invention, the substantially rigid center is made from any of the
following materials: fluoro-siloxane acrylate, siloxane acrylate,
or poly-styrene siloxane acrylate.
[0028] The substantially rigid center section may have a thickness
that may range between about 0.03 millimeters (mm) to about 0.5
mm., and a diameter that may range between about 4.0 mm. to about
12.0 mm. The overall diameter of a hybrid contact lens constructed
according to the present invention may range between about 10.0 mm.
to about 18.0 mm.
[0029] The substantially rigid center may have a spherical or
ellipsoidal ocular (i.e., eye-facing) surface. Unlike soft lenses,
the substantially rigid center of the present invention contact
lens is resistant to protein deposition. One feature of the present
invention contact lens is that it is also highly resistant to
foreign body migration as well as dislodgement from the eye during
contact sports, or other vigorous activities. A contact lens
constructed according to the present invention also provides
excellent centering and vision correction for irregular corneas
created by trauma or surgery.
Hybrid Contact Lens Geometry
[0030] One embodiment of the present invention comprises a central
substantially rigid gas permeable portion having a posterior
surface that is either spherical, aspherical or toroidal, which is
chosen to approximate the overall toricity and sagittal depth of
the cornea to be fitted. The rigid gas permeable portion may be
optically clear with only the reduction in light transmission
normally found in similar polymerized materials. In one embodiment
the rigid portion contains colorants and additives that narrow the
band of light transmitted by the lens to reduce the chromatic
aberration of the lens-eye system. The anterior surface of the
rigid portion may also have surface modification to correct the
total low and high order aberrations of the lens-eye system.
Further, the surface profile of the anterior surface may be
modified to register the low and high order aberrations over the
optical system of the eye to account for the consistent natural
displacement of the contact lens when applied to the eye. In
addition, the surface profile of the anterior surface may be
modified to contain a multi-focal feature for the correction of
presbyopia. Also, the anterior surface of the lens may be treated
to reduce the variance in the pre-lens tear film.
[0031] In another embodiment of the present invention, the
substantially rigid contact lens portion is joined to an outer soft
hydrophilic portion by an intermediate adhesion enhancement zone.
The adhesion enhancement zone may contain a material that bonds to
the substantially rigid portion and to the soft hydrophilic
portion. The soft hydrophilic portion may have a posterior surface
that is spherical, aspherical, toroidal or rotationally
asymmetrical to approximate the overall or meridional sagittal
depth of the peripheral cornea, limbal region and sclera. The
anterior surface of the soft portion may be modified to produce a
thickness variation in the form of prism ballast or thin zones that
utilize lid interaction to produce a resultant rotational
stability.
[0032] The soft section or skirt of the contact lens is designed to
control rotation by various methods. The methods include prism
ballasting, thin zones, and rotationally asymmetrical contours that
match the asymmetry of the cornea, limbus and sclera. In the
preferred embodiment the superior portion of the lens is thinner
than the inferior portion.
Methods of Manufacturing a Hybrid Contact Lens
[0033] Referring to FIGS. 1-5, one method of manufacturing a hybrid
contact lens according to the present invention will now be
described. This method results in a fracture resistant product that
is inexpensive to manufacture.
[0034] Shown in FIG. 1, a rod 10 of rigid gas permeable material is
cast having the desired characteristics. Upon the completion of the
curing the rod is precision ground to produce a substantially
uniform diameter. The rod is then machined by tool 15 into a
primary blank 17 having an anterior diameter 20 designed to conform
to the collet of a computer numerically controlled lathe and a
posterior diameter 25 designed to conform the outermost diameter of
the hydrophilic portion of the lens for positioning in a tube, cup,
or other containing device. The anterior diameter 20 may range from
6 millimeters (mm) to 24 mm, and the posterior diameter 25 may
range from 6 mm to 24 mm. In one embodiment, the anterior diameter
20 may be a separate material that is bonded or otherwise attached
to the primary blank 17 for enduring the clamping force of a lathe.
The intermediate portion of the primary blank 17 is simultaneously
machined to have a predetermined angle 30 for the interface of the
rigid and hydrophilic material in the finished lens.
[0035] One manufacturing method of the present invention has the
posterior diameter 25 substantially meet, or exceed, the
hydrophilic section outermost diameter 35, that is, the outermost
diameter of the soft section of the contact lens, as shown in FIG.
4. In this embodiment, a boundary material 40 is then applied to
produce a resultant wall, or cup to receive, and retain the
hydrophilic liquid polymer. Alternatively, the primary blank 17 may
be inserted into a cup, tube or other containing device to receive
the hydrophilic material.
[0036] An alternative manufacturing method of the present invention
includes the application of an adhesion promoter to the primary
blank 17, followed by the casting of the hydrophilic polymer into
the liquid holding device formed by either the boundary material
40, tube, cup or other containing device.
[0037] In yet another embodiment, the primary lens blank 17 is
mounted via the anterior diameter 20 in the collet of a computer
numerically controlled lathe that is programmed to produce the
aspherical posterior surface profile in a manner that the profile
does not require polishing, or may only need a light buff, or
polish. The posterior surfaced button is then mounted to a lens
block wherein the axis of the block passes through the geometric
center of the lens 45, shown in FIG. 4.
[0038] The assembly with the posterior surfaced button is remounted
in the collet of a computer numerically controlled lathe, such as
the Optoform 80 with Variform attachment, or equivalent type that
is capable of producing rotationally symmetrical or non-symmetrical
surfaces to high, or quarter wavelength accuracy that preferably
require a light buff, or no supplemental polishing (VARIFORM and
OPTOFORM are trademarks of Precitech, Inc., of Keene, N.H.). It
will be appreciated to those skilled in the art that other types of
lathes may be employed. The finished lens is then removed from the
lathe, with or without a light buff, deblocked and cleaned followed
by. anterior lens surface treatment. Finally the lens undergoes
hydration-extraction, sterilization and packaging.
[0039] Alternative manufacturing methods of the present invention
may include: molding of the posterior surface and diamond turning
of the molded blank; contour cutting of the anterior surface of a
posterior curve finished blank; etching the anterior surface of a
posterior curve finished blank or predicate lens anterior surface;
thin film deposition of a predicate lens anterior surface; and
laser ablation of a predicate lens anterior surface.
[0040] Another manufacturing method may include molding or lathing
a standard base curve with a standard or semi-customized front
surface, then using a thermal or laser energy to modify the
reflective index of the center material to a desired optical
requirement. This method replaces custom lathing or molding
expenses. Another method may include molding the posterior and
anterior surfaces, and yet another embodiment may include a
mechanical force or thermal molding manufacturing method.
[0041] Another method of manufacturing a hybrid contact lens
according to the present invention is illustrated in FIG. 5. Step 1
shows a rod of fluorosiloxane acrylate RGP material that will
comprise the substantially rigid section of the hybrid contact
lens. It will be appreciated to those skilled in the art that other
types of materials may be employed. These other materials may
include the following monomers, monomer mixtures, or their
derivatives: trimeththyl-siloxyl; methyl-methacrylate;
ethyl-methacrylate; ethylene glycol di-methacrylate; octafluoro
pentyl-methacrylate, tetra-methyldisiloxane, ethylene glycol
di-methacrylate, pentafluoro phenylacrylate, 2-(trimethylsiloxyl)
methacrylate, bis(2-metharyloxyphenyl) propane,
N-[2-(N,N-dimethylamino)ethyl], onethacrylate,
N-[2-(n,n-dimethylamino)ethy], methacryalte, vinyl-pyrolidone,
N,N-dimathacrylamide, acrylamine, hydroxyethyl methacrylate,
siloxane ethylene glycol di-methacrylate, trifluoroethyl
methacrylate, pentafluorostyrene, pentafluoropropyl methacrylate,
unsaturated polyester; p-vinyl benzyl hexafluoroisopropyl ether,
and siloxanylalkylamide.
[0042] The rod, or button shown in Step 1 of FIG. 5, will
preferably have a 5 millimeter (mm) to 22 mm diameter and be 2 mm
to 15 mm in length. In one embodiment, the button may be bonded to
another material for a subsequent operation, and as a possible cost
saving. In Step 2, a plunge tool is used to remove unnecessary hard
material and allow a solid section of material on one side for
subsequent operations. Another method may use the plunge tool to
form the button assembly from Step 1, with a shape similar to FIG.
2.
[0043] In Step 3, a spacer is formed on the gripping side of the
blank for the next operation, or the blank can be bonded to a
pre-form containing device to skip Step 4.
[0044] In Step 4, a tape, or other media that provides a retaining
wall to hold the soft material during polymerization is applied to
the blank. In Step 5, an adhesion promoter may be applied to the
hard material and then the soft material is poured inside the
retaining wall, or other containing device, and allowed to cure. In
Step 6, the spacer, or containing device, is removed and the blank
is ready for subsequent manufacturing operations.
[0045] Another method of manufacturing a hybrid contact lens
according to the present invention comprises the use of a molded
cup. In one embodiment, a pre-mold of a cup is created by using a
bondable material that can be bonded by both hard and soft contact
lens materials. This molded cup can be either usable in the
finished lens or removed during the casting process. A preferred
embodiment molded cup will have an optimized angle to maximize the
bonding strength between the hard and soft contact lens materials.
In addition, the molded cup may have a special gripping area for a
subsequent lathing operation.
[0046] One method of manufacturing a molded cup of the present
invention includes pouring a hard monomer to the open side of the
cup and placing the cup under a pre-programmed curing environment.
The cup is then placed over a plastic container for containing a
soft monomer fluid. The soft monomer fluid is then poured to the
open side of the plastic container and the assembly is placed under
a pre-programmed curing environment. After the assembly is fully
cured, it is ready to be lathed into a finished hybrid contact
lens.
[0047] Another method of manufacturing a hybrid contact lens
according to the present invention comprises a molded base curve
cup. In one embodiment, a base curve cup is molded to include a
base curve surface and an edge profile on a pre-determined
diameter, with a soft monomer retaining wall on one side, and a
special gripping area for subsequent lathing operations on the
other side.
[0048] Yet another method of manufacturing a hybrid hard-soft
contact lens of the present invention comprises using a molded base
curve cup or fully-molded cup that has centering webs, or other
indicators that ensure the device is centered. A pre-molded
material separation cup is placed on either the base curve side of
the cup or the front surface side of the cup, preferably to achieve
a centering of a meeting area, or junction surface between the hard
and soft contact lens materials.
[0049] Hard monomer is then poured in the center of the pre-molded
material separation cup. The hard monomer will ultimately become
the substantially rigid center second of the hybrid hard-soft
contact lent. The assembly is then placed in a curing environment,
and cured. Then soft monomer is poured into the area between the
hard core material and the cup. The soft monomer is then cured, and
then the assembly can be lathed to form a finished hybrid hard-soft
contact lens, or the assembly may be molded so as to eliminate the
need of subsequent lathing or machining.
[0050] Alternatively, this process may be reversed so that soft
monomer can be poured into the outside of the material separation
cup. The assembly is then placed in a curing environment, and then
cured. Then hard monomer is poured into the area between the soft
material separation cup and the cup. The hard monomer is then
cured, and then the assembly can be lathed to form a finished
hybrid hard-soft contact lens or the assembly may be molded so as
to eliminate the need of subsequent lathing or machining.
[0051] Yet another molding method may be employed where both hard
and soft monomer are poured together into a pre-mold cup, and then
these two monomers are cured together and subsequently machined, or
alternatively, a hard-soft contact lens is directly formed without
machining.
[0052] Referring to FIG. 6, methods of coupling the hard section of
the contact lens to the soft section will now be described.
Conventional hybrid contact lenses are generally not durable, in
part because of the fragile connection between the hard and soft
sections of the lens. One feature of the present invention is that
a variety of coupling configurations are contemplated that securely
couple the hard and soft sections of a hybrid contact lens.
[0053] One embodiment of the present invention employs an angled,
or sloped surface between the hard and soft contact lens sections,
thereby increasing the surface area, and thus the bonding force, or
strength between the two sections. Other embodiments use a variety
of different surface features, or surface geometries that increase
the durability and comfort of a hybrid contact lens.
[0054] For example, the bonding angle 50, shown in FIG. 6, may vary
from almost 0 degrees to almost 90 degrees. That is, if a contact
lens constructed according to the present invention was pressed
against a flat surface, the angle defined by the interface between
the hard and soft sections of the lens could vary from almost
parallel to the flat surface to almost perpendicular to the flat
surface.
[0055] In addition, the interface between the hard and soft
sections of the contact lens may include a variety of surface
configurations, or geometries 55. As shown in FIG. 6, these surface
geometries 55 may include ledges, protuberances, or substantially
V- or W-shaped projections. Other surface geometries 55 may include
serrations, gradations, or any other shape that is not
substantially straight, or planar.
[0056] Referring now to FIG. 6A, a preferred hard-soft lens bonding
method is illustrated. In this embodiment of the present invention,
increasing the surface area between the rigid and soft lens
components increases bonding strength between the two materials and
minimizes lens breakage, or failure. Another advantage of this
embodiment is that is provides a smooth transition between the
rigid or hard, and soft materials. This produces an exceptionally
comfortable lens.
[0057] As shown in FIG. 6A, an interface, or junction 75 between
the hard, or substantially rigid lens material 65, and the soft
lens material 70 is illustrated. Also shown is angle "A" that may
range between about 95 degrees to about 170 degrees. In a preferred
embodiment, angle A ranges between about 110 degrees to about 165
degrees. As illustrated, the interface between the hard, or
substantially rigid lens material 65, and the soft lens material 70
is substantially V-shaped. Put differently, the interface comprises
two intersecting planes that meet within the lens. This lens
junction configuration provides a safety feature in the unlikely
case of lens material separation during wear. Because of the
V-shape, the edge of the hard lens material 65 is not "blade"
shaped, and thus a sharp edge will not contact the cornea or
eyelid, eliminating the risk of cuts, or abrasions.
[0058] The hard and soft sections of a contact lens constructed
according to the present invention may be joined, or coupled by a
bonding material or resin comprised of the following monomer
mixtures or their derivatives: vinylacetate; trifluoroethanol;
methacrylate; ethanediamine; 2-hydroxyethylmethacrylate (HEMA) and
other esters of methacrylic acid formulated from acrylic bases;
fluorine; silicone; fluorine/silicone; styrene and resultant
polymers such as polystyrene; fluorine/styrene; and
silicone/styrene.
[0059] The soft section of the contact lens constructed according
to the present invention may be comprised of a variety of
materials. These materials may include the following monomer
mixtures or their derivatives: poly HEMA; hydroxyethyl acrylate;
dihydroxypropyl methacrylate; polyethylaneglycol; acetoxysilane;
trimethylesiloxy; ethyleneglycol-dimethacrylate; phenylethyl
acrylate; and polyethylene oxide. It will be appreciated to those
skilled in the art that other types of materials may be
employed.
Hybrid Contact Lens Surface Treatments
[0060] One feature of the present invention is that a variety of
contact lens surface treatments are contemplated. These surface
treatments may be added, for example, for the purpose of improving
the comfort of the lens by means of improving the in-vivo wetting
of the lens material. Another reason for using surface treatments
is to create a uniform pre-lens tear film thickness. Variations in
pre-lens tear film thickness induce aberrations while a uniform
pre-lens tear film thickness allows the other aberration
corrections to reach full effectiveness.
[0061] One embodiment of a hybrid contact lens constructed
according to the present invention may include a surface treatment
that provides uniform pre-lens tear film thickness between normal
blinking action. These treatments may comprise one or more of the
following embodiments: 1) Plasma--the lens is placed in the
presence of gases that are modified by oscillating electromagnetic
energy. This creates a surface oxidation that generate functional
groups such as. OH or NH on the lens surface, which make the lens
surface more wettable; 2) Ionic surfactants--polar molecules are
presented to the ionic lens surfaces with a resultant bonding of
the molecules to the surface. An example is sodium dodecyl sulfide.
The 12-carbon chain combined with lauryl sulfonic acid provides a
substrate that supports a more uniform tear film thickness; 3)
Non-ionic surfactants--The lens may be exposed to non-ionic
surfactants that provide a film on the lens. An example is an
ethylene glycol chain; 4) Soluble polymers--films of soluble
polymers can be applied to the rigid gas permeable material after
manufacturing. Examples are TEFLON and HEMA. Other types of surface
treatments are also contemplated.
Methods of Prescribing and Fitting a Hybrid Contact Lens
[0062] The present invention also contemplates methods of
prescribing and fitting a hybrid contact lens. One method relates
to non-rotating lenses for correcting high order aberrations that
include methods of placing the coordinates of the aberration
measurement over the coordinates of the pupil. Another comprises
methods of placing a multifocal over the coordinates of the pupil
and customizing the design of the multifocal with measurements of
high order aberrations and pupil size.
[0063] One method of prescribing and fitting a hybrid contact lens
employs a set of precision hybrid lenses with either spherical,
aspherical or toroidal posterior surfaces and spherical, aspherical
or toroidal anterior surfaces. For a final monofocal lens, one
embodiment contains a posterior aspherical surface and an anterior
spherical surface. For a final multifocal lens one embodiment
contains a posterior aspherical surface and an anterior aspherical
surface.
[0064] One prescribing method of the present invention employs a
central registration mark or marks concentric with the lens
geometric center that are placed on either the anterior or
posterior surfaces or within the matrix of either the rigid central
portion, the intermediate adhesion enhancement zone or in the soft
portion of a contact lens. In the preferred embodiment the rigid
portion is at least 9 mm in diameter and a minimum of three marks
are placed at a chord diameter of about 8 mm. In the preferred
embodiment the diameter of the overall lens is approximately 14.0
mm.
[0065] A contact lens from the set with a posterior rigid surface
that approximates the sagittal depth of the respective eye over the
chord diameter of the rigid portion is placed on the eye and
allowed to equilibrate. The degree of rotational and translational
movement is observed. In the preferred embodiment the movement
observed should be less than 5 degrees rotational and 0.3 mm
translational. Upon determination that the movement meets the
required limit the residual high and low order aberrations are
measured through the lens along with the relative coordinates of
the lens marks and the pupil margin, limbal margin or other
anatomical features. In the preferred embodiment an instrument
having the capability of detecting the lens marks and the pupil
margin along with the residual high and low order aberrations is
used.
[0066] An alternative embodiment of the present invention may
include infrared-responsive marks, such as one or more registration
marks, one or more concentric marks, or other suitable marks, which
emit or reflect infrared light. For example, some types of
wavefront aberrometers employ infrared light, which is generally in
the form of a laser. During examination of an eye fitted with a
hybrid hard-soft contact lens constructed according to the present
invention, the infrared-reflecting marks in the hybrid lens will be
easily visible, enabling simultaneous evaluation of registration
error, as well as aberrations. In one embodiment, indocyan dye is
employed, but it will be appreciated that other dyes, powders, or
other types of infrared-responsive products may be employed.
[0067] Another method of prescribing and fitting a hybrid contact
lens employs a set of precision rotating and non rotating hybrid
contact lenses having known ocular surface profiles, optical
corrections and thickness profiles. In one embodiment, the lenses
contain circumferential marks in the mid periphery. A lens is
selected and applied to the eye and allowed to equilibrate. The
coordinates of the marks and the pupil are determined. The
aberrations of the lens-eye system are measured. A mathematical
model provides analysis of the known thickness profile, the
registration error of the coordinates of the lens and the pupil,
and the residual lens-eye aberrations to derive the computer
numerically controlled lathe files for diamond turning a resultant
thickness profile for a final contact lens having the same ocular
surface profile.
[0068] For example, one prescribing and fitting method of the
present invention may include the steps of: selecting the initial
lens to conform to the shape of the underlying cornea; capturing an
image of the circumferential marks and the pupil margin; measuring
the residual low and high order aberrations of the lens-eye system;
performing analysis utilizing the known ocular surface profile of
the lens, the initial lens thickness profile, the registration
error, and the residual lens-eye aberration error to determine the
resultant files for generating a final contact lens.
[0069] Another method of prescribing and fitting a hybrid contact
lens employs a set of contact lenses having a known central zone
ocular surface geometry, thickness, anterior surface geometry and
diameter. The preferred residual lens eye aberration correction and
coordinate disparity are determined by clinical measurement, and
the thickness profile variation is derived by computer modeling, or
other methods, in order to specify a superiorly performing
lens.
[0070] Yet another method of prescribing and fitting a hybrid
contact lens employs a set of contact lenses with fixed ocular
surface geometries, overall diameters and front surface geometries,
over which clinical measurements are made from which the final
prescription parameters are derived by computation, or other
methods.
[0071] Another method of the present invention comprises correcting
visual acuity deficiencies in presbyopia by reduction of the
residual lens-eye aberrations. The method uses a set of hybrid
contact lenses having a known ocular surface profile and thickness
profile and containing circumferential marks for the purpose of
registration of the final optical correction with the 5 coordinates
of the optical system of the eye. The method steps may include:
selecting the initial lens to conform to the shape of the
underlying cornea; capturing an image of the circumferential marks
and the pupil margin; measuring the size of the pupil in photopic,
mesopic and/or scotopic illumination; measuring the residual low
and high order aberrations of the lens-eye system; and performing
analysis utilizing the known ocular surface profile, the initial
lens thickness profile, the registration error, the pupil size and
the residual lens-eye aberration error to determine prescription
information for generating a final contact lens. In one embodiment
of this method, the diameter of the near focused optical correction
may be in the range of about 1.8 mm to about 4.0 mm.
[0072] Another method of the present invention employs a multifocal
contact lens and corrects visual acuity deficiencies in presbyopia
by reduction of the residual lens-eye aberrations. The method uses
a set of multifocal hybrid contact lenses having a known ocular
surface profile and thickness profile and containing
circumferential marks for the purpose of registration of the final
optical correction with the coordinates of the optical system of
the eye. The method steps may include: selecting the initial lens
to conform to the shape of the underlying cornea having a
multifocal anterior surface; capturing an image of the
circumferential marks and the pupil margin; measuring the size of
the pupil in photopic, mesopic and/or scotopic illumination;
measuring the residual low and high order aberrations of the
lens-eye system; and performing analysis utilizing the known ocular
surface profile, the initial lens thickness profile, the
registration error, the pupil size and the residual lens-eye
aberration error to determine prescription information for
generating a final multifocal contact lens. In one embodiment of
this method, the diameter of the near focused optical correction
may be in the range of about 1.8 mm to about 4.0 mm.
[0073] Another method of the present invention employs a multifocal
contact lens and corrects visual acuity deficiencies in presbyopia
by reduction of the residual lens-eye aberrations. This method also
incorporates information relating to a light transmittance pattern.
The method uses a set of multifocal hybrid contact lenses having a
known ocular surface profile and thickness profile, light
transmittance pattern, and containing circumferential marks for the
purpose of registration of the final optical correction with the
coordinates of the optical system of the eye. The method steps may
include: selecting the initial lens to conform to the shape of the
underlying cornea having a multifocal anterior surface; capturing
an image of the circumferential marks and the pupil margin;
measuring the size of the pupil in photopic, mesopic and/or
scotopic illumination; measuring the residual low and high order
aberrations of the lens-eye system; and performing analysis
utilizing the known ocular surface profile, the initial lens
thickness profile, the registration error, the light transmittance
pattern, the pupil size and the residual lens-eye aberration error
to determine prescription information for generating a final
multifocal contact lens. In one embodiment of this method, the
diameter of the near focused optical correction may be in the range
of about 1.8 mm to about 4.0 mm.
[0074] The above-described methods of prescribing and/or fitting a
hybrid contact lens may also employ additional method steps or
additional devices. For example: the method of determining the
difference in the coordinates of the center of the circumferential
lens marks and the pupil margin may incorporate a reticle of a
biomicroscope or a camera with subsequent manual or electronic
digital image detection. In addition, the method of measuring the
residual aberrations of the lens-eye system may incorporate
Shack-Hartmann aberrometry, aberrometers utilizing Tscherning
technology, laser ray-tracing or Talbot interferometry
technology.
Correction for Various Components of the Visible Light Spectrum
[0075] Aberrometry performed with the contact lens in place
provides us with knowledge of the angles that the rays emerging
from the anterior lens make with respect to the visual axis. In the
perfect case, the rays would all emerge parallel to the visual
axis. But as illustrated in FIG. 7, in the presence of aberrations
these rays make an angle with respect to the visual axis and this
angle is not restricted to the plane of the paper. To correct these
aberrations, there are generally two variables to play with. The
first variable is the slope of the contact lens at the point each
ray emerges from the contact lens. Changing this slope will change
the direction of the ray exiting the eye via Snell's Law. There
will exist a slope of the anterior contact lens surface that causes
the ray to exit parallel to the visual axis. The second variable is
the local lens thickness at the point where each ray exits the
contact lens. As this thickness is adjusted, the- slope of the
surface at this point also needs to change in order to keep the
emerging ray parallel to the visual axis. There will exist a set of
local thicknesses and slopes that simultaneously cause all of the
emerging rays to be parallel to the visual axis and keep the
overall thickness of the lens reasonable, that is, not too thin or
too thick.
[0076] Aberrometry is normally only performed at one wavelength,
usually in the infrared. However, as illustrated in FIG. 8, the
slopes of the various rays will depend on the color of the light.
In general, blue lights rays will be more convergent than the green
light rays. The red light rays will be more divergent than the
green light rays.
[0077] The dilemma now is which color rays should be made parallel
to the visual axis. If the eye responded equally to all colors in
the visible range (wavelengths of about 380 nanometers (nm) to
about 780 nm), you would make the rays that corresponded to the
middle wavelength parallel to the visual axis. In this manner, half
of the light would be diverging and half of the light would be
converging as it left the eye.
[0078] Referring to FIG. 9, for a uniform response, the center
wavelength of the visible spectrum would be ideal for correcting
aberrations since, the equal areas of the rectangles on either side
of this wavelength means equal amounts of energy is distributed
around this wavelength.
[0079] However, the eye does not respond to all wavelengths the
same. The photopic response curve, illustrated in FIG. 10, shows
that the eye is more sensitive to the red/green end of the
spectrum. The same sort of concept as described above can now be
used to determine the ideal wavelength for correcting aberrations.
The ideal wavelength gives equal areas under the photopic response
curve on either side, as shown in FIG. 10.
[0080] In addition to the variation in response of the eye to
different colors, the present invention may also vary the
transmission of the contact lens to different colors. This may be
beneficial to reducing the effects of chromatic aberration in the
eye. If the contact lens transmission is multiplied by the photopic
response of the eye, a net response of the eye results, as
illustrated in FIG. 11. One ideal wavelength is based on this net
response which again gives equal areas under the curve. This ideal
wavelength is then used as the target for correcting aberrations by
the means described above.
[0081] For example, for either a final monofocal or multifocal
lens, one embodiment hybrid contact lens constructed according to
the present invention contains colorants that reduce the
transmission at both the blue and red end of the visible spectrum
thereby narrowing the band of transmitted light and potentially
shifting the peak of the transmission curve of the lens. A contact
lens of the present invention may therefore include color additives
for the purpose of reducing light transmission, or color additives
for the purpose of reducing chromatic aberration.
[0082] Thus, it is seen that a hybrid hard-soft contact lens
system, method, and article of manufacture is provided. One skilled
in the art will appreciate that the present invention can be
practiced by other than the above-described embodiments, which are
presented in this description for purposes of illustration and not
of limitation. The description and examples set forth in this
specification and associated drawings only set forth preferred
embodiment(s) of the present invention. The specification and
drawings are not intended to limit the exclusionary scope of this
patent document. It is noted that various equivalents for the
particular embodiments discussed in this description may practice
the invention as well.
* * * * *