Contact lens mold packaging

A contact lens package made from one of the mold parts used to mold a contact lens, the lens being packaged in a storage cavity separate from a molding surface of the mold part.

FIELD OF THE INVENTION 
The present invention pertains to the field of contact lens packaging means 
and the use of molding apparatus as the final packaging means. 
BACKGROUND OF THE INVENTION 
Cast molding is a known method for producing contact lenses. Generally, 
monomer mix is introduced into two mold parts which form the mold 
assembly. The monomer mix is then cured in the mold assembly to form a 
contact lens. The monomer mix is generally placed in an anterior, or 
female mold. The anterior mold has a concave surface that is used to shape 
the anterior surface of a lens. A posterior, or male mold is then brought 
into contact with the anterior mold so that the monomer mix is located in 
the cavity formed between the two molds. The posterior mold has a convex 
surface used to shape the posterior surface of the lens. The monomer mix 
is cured within the mold to form a contact lens. The anterior and 
posterior lens molds are then separated, and the cured lens is removed and 
placed into a package able to withstand the requirements for storage and 
shipping. The lens is usually packaged and shipped in the hydrated state 
so that, in addition to the lens, the package usually contains a storage 
solution. 
Molds are typically discarded after the lens has been removed. While some 
of the mold materials may be recyclable, significant waste occurs and cost 
is added to the overall lens manufacturing process. 
Recently, there has been interest in using molds, after the molding process 
is completed, as the lens package in which the finished lens is shipped 
and stored. U.S. Pat. No. 5,036,971 discloses the use of the anterior or 
female mold, as a packaging means for the molded lens. U.S. Pat. No. 
5,143,660 discloses the use of the posterior or male mold as a packaging 
means for the molded lens. In both of these U.S. patents, the molding 
surface forms a part of the lens storage cavity. An advantage of these 
prior art approaches is that the lens can remain on the same surface from 
the time it is formed until it is removed from the package by the end 
user. 
However, a problem with the approach disclosed in the patents is that the 
dimensions of such molding cavities may not be suitable for use as a 
storage chamber or final lens package for the lens. The cavity or chamber 
may have walls which are too steep to facilitate lens removal by the 
practitioner or patient. Further, the cavity in which the contact lens is 
molded and retained may have insufficient volume and therefore cannot hold 
a desired amount of lens solution thought to be required for storage and 
shipping. 
In addition, in the case of hydrogel lenses, the lens is often hydrated 
after molding, but before shipping. During hydration, the lens swells. The 
dimensions of the anterior and posterior molding surfaces are generally 
smaller than the diameter of the hydrated lens. Therefore, the lens may 
not fit in the mold cavity in its hydrated state. 
SUMMARY OF THE INVENTION 
The present invention is a contact lens package comprising a contact lens 
mold having a lens molding surface used for lens formation and a sealable 
contact lens storage cavity distinct from the lens molding surface. 
More specifically, the present invention is a contact lens package 
comprising a mold having a concave lens molding surface, a convex surface 
opposite the molding surface and a substantially cylindrical wall 
extending from the molding surface which forms a sealable contact lens 
storage cavity. 
In a further embodiment a contact lens package is disclosed comprising a 
mold having a convex lens molding surface, a concave surface opposite the 
molding surface and a substantially cylindrical wall extending from the 
molding surface which forms a sealable contact lens storage cavity.

DETAILED DESCRIPTION OF THE INVENTION 
Preferred molds for use as the contact lens packages of this invention are 
of the kind described in U.S. Pat. No. 5,271,875. More specifically, 
preferred anterior molds have a concave lens molding surface, a convex 
surface opposite the molding surface and a substantially cylindrical wall 
extending from the molding surface so as to form a sealable lens storage 
cavity with the convex surface. 
Preferred posterior molds have a convex lens molding surface, a concave 
surface opposite the molding surface which forms a sealable lens storage 
cavity. Particularly preferred posterior molds have a hollow substantially 
cylindrical base. Preferred embodiments will now be described with 
reference to the Figures. 
FIG. 1 shows an exploded view of a lens mold assembly after curing. The 
posterior mold 1 has a posterior contact lens storage cavity 2 visible on 
the top of the posterior mold and a posterior lens molding surface which 
is not visible. The anterior mold 3 has an anterior lens molding surface 
4, and an anterior contact lens storage cavity which is not visible. The 
anterior and posterior lens molding surface, when brought together form 
the lens molding cavity in which the contact lens is molded. When the 
monomer mix is injected onto the lens molding surfaces and cured into a 
lens, the mold parts are removed and the cured contact lens 5 is released 
from the lens molding surfaces. 
As shown in FIG. 2, in a preferred embodiment, an anterior mold 3 includes 
a substantially cylindrical wall 6 which blends into a tapered head 
portion 6a. The tapered head portion 6a serves as a centering means to 
center the anterior mold within a complimentarily shaped taper in the 
posterior mold. The anterior mold also includes a concave anterior lens 
molding surface 4 formed to provide the desired anterior surface to the 
cured lens. If the anterior mold is to be used as a package for the 
finished lens, the lens is placed in the lens storage cavity 7. Because of 
its concavity, during the lens molding procedure, the curable monomer mix 
will be placed onto the anterior lens molding surface 4. 
As shown in FIG. 3, the posterior mold 1 includes a substantially 
cylindrical wall 8 dimensioned to allow the anterior mold 3 to fit the 
posterior mold 1 complementarily as discussed above. An annular flat 
surface 9 is shown. The posterior mold 1 includes a posterior lens molding 
surface 10, the opposite side of which defines the bottom surface of the 
lens storage cavity 2. The annular flat surface 9 may optionally have a 
raised rim (not shown) which could interlock with, or otherwise facilitate 
attachment of a sealing cover (not shown) to the top flat portion as would 
be apparent to one skilled in the packaging field, thereby sealing the 
posterior storage cavity 2. 
The thicknesses of the posterior and anterior molds are selected to be 
sufficient so that the mold cavity defining surface is rigid and does not 
deform under curing or polymerizing stress unless such material 
deformation is specifically desired or critical to proper lens formation. 
In a preferred embodiment, the substantially cylindrical wall 8 of the 
posterior mold 1 is joined to an annular flat portion 9 at shoulder 11. 
The posterior mold 1 further includes a portion of the base 12 which is 
relatively thinner than the remainder of the mold to provide an internal 
diameter that is larger at the base than that defined by the remainder of 
the mold, thereby facilitating access for anterior mold 3. Base portion 12 
includes optionally includes a stepped diameter which leads into taper 13. 
Taper 13 provides an automatic centering means for the alignment and 
centering of anterior mold 3 with respect to posterior mold 1. It is 
understood that the present invention contemplates the use of any two 
molds each having a complementary molding surface which may be brought 
into close association for the purpose of creating a molding cavity in 
which a contact lens is molded. 
Taper 13 reverses at 14 and leads to posterior lens molding surface 10 
having a generally spherical surface. "Generally spherical" is understood 
to include shapes which are not strictly spherical such as aspheric or 
toric shapes. 
As shown in FIG. 2, anterior mold 3 includes a substantially cylindrical 
wall 6, tapered head 6a and "generally spherical" (as defined above) 
anterior lens molding surface 4. The diameter of taper in the anterior 
mold 3 is selected so that it is slightly smaller than the corresponding 
diameter of taper in the posterior mold 1. This ensures that the mold 
sections seat correctly while also ensuring that they are properly 
centered. Preferably the molds seat with a 0 to 20 micron clearance 
between tapers 6 and 13; more preferably with a 0-10 micron clearance. 
FIG. 4 cross-sectionally illustrates posterior mold 1 and anterior mold 3 
in their assembled form. Posterior mold 1 seats in close association 
against anterior mold 3. Tapers 13 and 6a meet with the above-noted 
clearance so as to center the anterior and posterior molds thereby 
preventing prism or other undesired defects caused by decentering. As so 
assembled, the two mold sections form a predefined mold cavity 15 in which 
curable contact lens monomer mix formulations such as polymerizable 
2-hydroxyethyl methacrylate (HEMA) may be held during curing. While such 
an embodiment is not depicted, it is understood that the present invention 
encompasses intentional decentration of the two mold parts for the purpose 
of inducing desired prism in the molded lens. It is further understood 
that the invention would be useful for contact the manufacture and storage 
of any type of lenses, and would be particularly useful for the 
manufacture and shipping of soft hydrophilic contact lenses including 
hydrogels which presently are shipped in the hydrated state. Hydrogels are 
hydrophilic polymers that absorb water to an equilibrium value and are 
insoluble in water due to the presence of a three-dimensional network. 
Hydrogels are generally formed of a copolymer of at least one hydrophilic 
monomer and a crosslinking monomer. The hydrophilicity is due to the 
presence of hydrophilic groups, such as alcohols, carboxylic acids, amides 
and sulfonic acids. The swollen equilibrated state results from a balance 
between the osmotic driving forces that cause the water to enter the 
hydrophilic polymer and the forces exerted by the polymer chains in 
resisting expansion. In the case of silicone hydrogel contact lenses, the 
copolymeric material further includes a silicone-containing monomer. 
Generally, the two mold parts, anterior and posterior, are substantially 
cylindrical with varying overall diameters such that the convex lens 
forming surface of the posterior mold comes into intimate contact or close 
association with the concave anterior mold lens forming surface. Intimate 
contact and close association are defined as being as close as the desired 
thickness of the contact lens being produced between the two cooperating 
mold parts. 
The substantially cylindrical walls of the posterior and anterior molds are 
sufficiently thick to withstand the whatever pressure which may be 
supplied to the mold assembly during the lens molding process. The lens 
mold assembly is understood to represent the anterior and posterior molds 
in close association with one another. In the preferred embodiment, if 
predetermined material deformation is required of the mold, the posterior 
mold is made from a material flexible enough to deform as needed, while 
also retaining its shape so that it may be used as a sealable contact lens 
package. The height of the substantially cylindrical walls is not 
critically important. However, in the preferred embodiment, the height of 
the cylindrical walls of the posterior mold is less than the height of the 
anterior mold to facilitate mold separation and lens release. 
As already described, preferred posterior molds have a convex lens molding 
surface and a concave surface opposite the molding surface which forms the 
lens storage cavity. Particularly preferred posterior molds have 
substantially cylindrical walls. The posterior and anterior lens storage 
cavities are preferably concave and convex respectively, at the bottom, 
but may be any desired shape or texture at the bottom. The storage cavity 
preferably has a diameter and volume capacity large enough to store a 
contact lens and lens storage solution. The bottom or side walls of the 
storage cavity may have features designed to assist in restricting the 
movement of the contact lens. The storage cavity may also have features to 
facilitate lens removal such as a particular slope or textured finish. 
The annular flat surface at the top perimeter of the storage cavity may 
itself have a rim or raised area to facilitate securing a sealing means to 
cover the contact lens storage cavity. The sealing means may be affixed to 
the rim via heat or chemical reaction or through any covering and sealing 
means as would be readily apparent to one skilled in the container field. 
The present invention contemplates using the molds and packages of the 
present invention in connection with the production of all types of 
contact lenses. Therefore any lens-forming material can be employed in the 
present invention. The materials may be hydrophilic, or hydrophobic, or 
mixtures of both. The resulting contact lenses may be hard lenses as 
exemplified by the rigid acrylic plastics including poly(methyl 
methacrylate); or such contact lenses may be flexible, hydrophobic lenses 
exemplified by the unsubstituted and fluoro-substituted polyethylenes, the 
silicone elastomers, and the like; or such lenses may be soft hydrogel 
lenses as already described. 
It is understood that materials for posterior and anterior molds may be 
selected in consideration of their physical properties such as their 
affinity for cured lens materials. Such affinity is useful if it is 
desired that the lenses are preferentially retained by either the anterior 
or posterior mold half upon their separation from one another during lens 
processing. It has been found that a combination of polypropylene (e.g. 
MARLEX.RTM. from Phillips 66) for posterior mold 1 and rigid unplasticized 
polyvinyl chloride (e.g. GEON.RTM. from B. F. Goodrich) for anterior mold 
3 provides a suitable combination of materials. Other materials would be 
readily apparent to the skilled practitioner and the same materials may be 
used for both anterior and posterior molds. 
After the curing takes place, the molds are separated. The cured contact 
lens preferably clings in a predetermined way to either the posterior or 
anterior lens molding surface. The lens is then removed from the molding 
surface, to which it was preferentially bound, by directly removing the 
lens from the mold surface. The lens may also be removed from the mold by 
allowing the lens to free itself from the mold, for example into an 
hydration tank, after it has been hydrated. 
As shown in FIG. 5, the lens 16 is then placed in the storage cavity 2 
portion of the posterior lens mold 1. The storage cavity 2 is preferably 
filled with a selected volume of lens solution 17. A cover 18 which is 
designed to remain in close association with the top of the lens mold 1 
may then be sealed to the top of the mold to seal the storage cavity 2 
through heat treatment, or via other sealing means as are known and would 
be readily apparent to one skilled in the field. 
A secondary package or tray into which a number of lens packages, such as 
those shown in FIG. 5 is further contemplated by the present invention. In 
one preferred embodiment, the base portion 12 of the lens package, which 
is preferably circular, fits into circular depressions present in the 
secondary package or tray. The use of a secondary package is thought to 
facilitate packaging and shipping. 
It is understood that the storage cavity on the molds of the present 
invention could just as effectively be incorporated into the anterior or 
female mold. In this way the lens would be sealed in a storage cavity in 
the anterior mold, unrelated to and distinct from the anterior lens 
molding surface. The lens package could then be shipped individually, or 
integrated into a secondary shipping package. 
As mentioned previously, the molds of the present invention are preferably 
injection molded or thermoformed from any suitable thermoplastic materials 
such as polyolefins (e.g. polyethylenes, polypropylenes, polybutenes), 
polyamides, polyesters, polysulfones or other plastics and plastic resin 
materials which are known by those skilled in the field to perform well as 
contact lens mold and contact lens packaging materials, with polypropylene 
being particularly preferred. The materials selected must also perform 
well regarding impermeability such that the lens solution is retained 
within the package for at least the shelf life duration of the lens and 
solution, and preferably for from three to five years. The selected 
material must also be able to withstand conditions used to sterilize the 
contents as required in the industry such as heat and various radiation 
procedures. The preferred material selected should also be impervious to 
bacteria and pathogens such that the sterility of the packaged lenses and 
accompanying solution is assured. 
The configuration illustrated in FIG. 4 of the cooperating molds is a 
preferred embodiment for positioning the mold surfaces. However, it will 
be apparent to those skilled in the field that other cooperating surface 
configurations provided on each of the mold members would be acceptable 
for the same purpose so long as the required spacing and alignment 
restrictions are achieved. For example, FIG. 2 shows the anterior mold 
fitting inside of the posterior mold which houses the storage cavity. It 
is understood that the present invention clearly contemplates a posterior 
mold which may fit inside of the anterior mold. 
The material to be used as a cover for the cavity may be made of a single 
layer, or is preferably a laminate of materials such as plastic (e.g. 
polypropylene) films and metal (e.g. aluminum) foils. Such a cover can be 
sealed to the top of the cavity of the package by means known in the 
packaging field, and may be preferably heat sealed. The cover should be 
sealed such that the sterility of the lens and solution contained in the 
sealed package is preserved until the package is opened. Since the storage 
must not evaporate for a potentially long shelf life, the cover should be 
made from a material which is impermeable. It is understood that lens 
identification or other labelling information can be printed or imprinted 
on the cover. 
In one embodiment of the present invention, the area around the inside or 
outside of the top of the posterior or anterior mold may be machined such 
that the area is "threaded". It is understood that the term "threaded" 
means that a helical or spiral ridge has been machined into a material. A 
plastic cover made from a selected material (e.g. polypropylene) may be 
threaded to match the threaded region on the mold. In this way, a hard 
plastic cover, for example, may be screwed into place over the previously 
sealed storage cavity. This would be especially advantageous since the 
posterior mold could also serve as a long term and extremely compact 
contact lens case after the plastic/foil seal has been broken and removed. 
Many other modifications and variations of the present invention are 
possible to one skilled in the field in light of the teachings herein. It 
is therefore understood that, within the scope of the claims, the present 
invention can be practiced other than as herein specifically described.