Polymeric ophthalmic lens with crosslinker containing saccharide residue

An ophthalmic lens, particularly a soft hydrogel contact lens, is disclosed. The lens can be derived from a crosslinked polymer made by reacting a hydrophilic monomer with a crosslinking amount of a polyfunctional compound containing a saccharide residue. The preferred hydrophilic monomer is actually a mixture of the following individual hydrophilic monomers: a) the reaction product of a free radical reactive monoisocyanate and a monoalkoxy polyalkylether, b) N,N-dimethylacrylamide, and optionally c)hydroxyethyl methacrylate. The preferred polyfunctional compound is a prepolymer derived from an alkoxylated glucose or sucrose. This prepolymer can be made by reacting glucose or sucrose, which has been ethoxylated or propoxylated, with a free radical reactive isocyanate which has been capped. The free radical reactive isocyanate can be capped by reacting it with a polyalkylether, such as polyethylene glycol, and then reacting this intermediate with a diisocyanate.

BACKGROUND OF THE INVENTION 
This invention relates to a crosslinked polymer derived from the 
polymerization of a hydrophilic monomer and a crosslinking agent. More 
specifically, it relates to such a polymer which has the properties 
desired for ophthalmic lenses, particularly soft hydrogel contact lenses. 
Soft hydrogel contact lenses are currently the lens design of choice for 
extended wear applications. These lenses are derived from the 
polymerization of a hydrophilic monomer such as hydroxyethyl methacrylate 
(HEMA). Other hydrophilic monomers can be used, such as 
N,N-dimethylacrylamide (DMA) and N-vinyl pyrrolidone (NVP), although these 
alternative monomers have not yet found as wide-spread an acceptance as 
HEMA for the fabrication of commercially viable contact lenses for daily 
or extended wear applications. 
A contact lens composed of the polymerization reaction product of HEMA 
(polyHEMA) is swollen in water to prepare a hydrogel. For higher 
water-containing hydrogels, the water content of the hydrogel lens is an 
important factor in patient comfort because the permeability of oxygen 
through the lens is dependent on its water content. Since the corneal 
tissue of the eye of a contact lens wearer needs oxygen to "breathe", the 
water content of the lens, and hence its oxygen permeability, are 
important factors in achieving an acceptable degree of wearer comfort and 
corneal health. 
Although polyHEMA lenses can be swollen with water to prepare hydrogels 
with minimally acceptable water contents and oxygen permeability, such 
lenses composed of polyHEMA alone do not exhibit sufficient mechanical 
properties for routine handling and care. Accordingly, commercially 
available contact lenses are derived from polymerizing not only HEMA, but 
also a crosslinking monomer to enhance the mechanical properties of the 
finished lens. The crosslinking monomer conventionally used is ethylene 
glycol dimethacrylate (EGDMA). While the crosslinking monomer improves the 
mechanical properties of the finished lens, and therefore enhances the 
handleability of the lens, it also has adverse consequences. High levels 
of conventional crosslinking agents serve to reduce the water content of 
the finished lens and increase its brittleness. The reduced water content 
lowers the permeability of oxygen through the lens, which in turn 
decreases patient comfort and corneal health over an extended period of 
wear. The increase in brittleness of the lens makes the lens more fragile, 
and therefore more susceptible to tearing. 
Since neither polyHEMA alone nor the reaction product of HEMA with a 
crosslinking agent has produced optimum properties for a soft contact 
lens, commercially available lenses typically incorporate additional 
monomeric components from which the lens is derived. For example, anionic 
monomers such as methacrylic acid (MAA) are frequently added to further 
increase the water content of the lens: and hydrophobic monomers, such as 
alkyl acrylates or methacrylates, are added to further enhance the 
mechanical properties of the finished lens. Unfortunately, there is still 
plenty of room to improve the desired properties for ophthalmic lenses, 
particularly soft hydrogel contact lenses, and so therefore numerous 
attempts have been made to develop such lenses from novel polymer systems. 
Numerous examples abound in the literature of attempts to fabricate 
hydrogel contact lenses from unique polymer systems. What follows is a 
discussion of some of the more relevant teachings with respect to these 
alternative polymers for use in fabricating ophthalmic lenses. 
U.S. Pat. No. 3,988,274 describes soft contact lenses made from a number of 
monomeric components designed to optimize oxygen permeability and 
strength. The predominant monomer is an alkylene glycol monomethacrylate 
such as HEMA, or a monomethacrylate of polyethylene glycol (monoester of 
PEG). The crosslinking monomer is a conventional polyfunctional monomer 
such as EGDMA, or a higher molecular weight crosslinker such as 
polyethylene glycol dimethacrylate. Acrylic or methacrylic acid is added 
to increase water content, and an alkyl ester of acrylic or methacrylic 
acid, such as N-hexyl methacrylate, is added to improve strength. 
U.S. Pat. 5,034,461 describes contact lenses made from copolymers of 
conventional ethylenically reactive monomers such as HEMA, or fluorinated 
analogs of these monomers, and a prepolymer. The prepolymer is prepared 
sequentially by first reacting an isocyanate-terminated polyol with a 
polyalkylene glycol, and then capping this reaction product with HEMA. 
U.S. Pat. No. 4,780,488 describes preparing a contact lens material from a 
crosslinked polymer of a polyfunctional monomer. In one embodiment, the 
polyfunctional monomer is made by first capping a polyalkylene glycol, 
e.g. polypropylene glycol (PPG), with a diisocyanate, and then 
functionalizing the capped polyol with ethylenic unsaturation by reacting 
it with HEMA. Dimensional stability may be improved by adding a 
conventional crosslinking agent. 
European Patent Application 321,403 describes contact lenses made from 
crosslinked polyvinyl alcohol (PVA). In one embodiment, a PVA derivative 
is prepared by reacting PVA with glycidyl methacrylate (GMA). The PVA/GMA 
can be copolymerized with a vinylic monomer composition containing a 
predominant amount of a hydrophobic monomer and a minor amount of a 
hydrophilic monomer. 
U.S. Pat. No. 4,921,956 describes preparing a reactive modifier which can 
be used to increase the water content of a soft contact lens made from 
hydrophilic polymers. The modifier, in one embodiment, contains a cyanate 
functionality which can be reacted with the hydrophilic monomer which is 
polymerized to form the lens. 
More recently, an attempt has been made to develop a contact lens from a 
polymer containing a glucose or sucrose derivative. U.S. Pat. No. 
5,196,458 discloses preparing a contact lens from a polymer containing 
such a glucose or sucrose derivative. A prepolymer is formed by reacting 
an alkoxylated glucose or sucrose with a capped, free radical reactive 
isocyanate, e.g. an ultraviolet light curable (UV-curable) isocyanate. The 
tree radical reactive isocyanate is capped by first reacting it with a 
polyalkyether, such as PEG or PPG, and then reacting this intermediate 
with a diisocyanate. In a related disclosure, European Patent Application 
394,496, published Oct. 31, 1990, teaches saccharide derivatives which can 
be polymerized to form a polymer for biomedical applications. In one 
embodiment, the saccharide derivative is a glycoside derivative prepared 
by reacting an alkyl glycoside, such as methyl glycoside, with an ester of 
acrylic or methacrylic acid, such as HEMA. 
Another attempt to fabricate ophthalmic lenses, especially soft hydrogel 
contact lenses, from alternative polymeric systems is described in 
European Patent Application 493,320, published Dec. 20, 1990. This 
publication teaches making lenses from the following reaction product: a) 
a polyalkylether capped with a UV-curable isocyanate (including tri- or 
tetrafunctional polyalkylethers), b) a fluoromonomer with ethylenic 
functionality, c) a hydrophilic monomer such as HEMA or DMA, and d) a 
conventional crosslinker such as EGDMA. 
While numerous attempts have been made to optimize the properties of 
ophthalmic lenses, particularly soft contact lenses, these attempts have 
fallen short of the ultimate goal of fabricating ophthalmic lenses with 
not only properties ideally suited for patient comfort and corneal health 
during extended wear, but also outstanding mechanical properties. What is 
truly needed is a polymer which has the requisite properties to achieve 
the highest degree of patient comfort and corneal health without 
appreciably sacrificing its mechanical properties when the polymer is 
fabricated into an ophthalmic lens, particularly a soft hydrogel contact 
lens. 
SUMMARY OF THE INVENTION 
In one aspect, the invention is a crosslinked polymer. The crosslinked 
polymer comprises the reaction product of a hydrophilic monomer and a 
crosslinking amount of a polyfunctional compound containing a saccharide 
residue. 
In another aspect, the invention is an ophthalmic lens. The ophthalmic lens 
comprises the crosslinked polymer described above. 
The crosslinked polymer of this invention exhibits the requisite array of 
properties particularly desired for ophthalmic lenses, especially soft, 
hydrogel contact lenses. Surprisingly, in preferred embodiments of this 
invention, incorporating the polyfunctional compound as a crosslinker in 
the polymer from which the soft hydrogel lens is derived actually enhances 
not only its mechanical properties, but also its properties associated 
with patient comfort and corneal health for extended wear applications. 
This is contrary to the changes in properties expected when a crosslinking 
monomer or prepolymer is incorporated into a polymer from which the lens 
is derived. 
Specifically, one of the improvements observed by incorporating the 
polyfunctional compound into the lens is that its modulus increases, and 
hence its handling properties correspondingly improve. But the beneficial 
improvements exhibited in the properties of the lens go beyond the 
improved modulus. In addition, the water content of the lens unexpectedly 
increases with the incorporation of the polyfunctional compound, so that 
oxygen permeability through the lens likewise increases to enhance patient 
comfort and corneal health. The increased water content of the lens is 
achieved while maintaining its elongation, which means that the lens does 
not become more brittle and hence more fragile. All of these noteworthy 
changes in properties are contrary to those changes exhibited when 
conventional crosslinking monomers such as EGDMA are incorporated into the 
monomer system from which the polymerized lens is derived. 
In a particularly preferred embodiment, the polymerization of the 
hydrophilic monomer and the polyfunctional compound occurs in the presence 
of an inert diluent in a mold for an ophthalmic lens. When preferred 
diluents are used in combination with a monomeric mixture incorporating a 
preferred polyfunctional compound as the crosslinker, the shrinkage of the 
polymerized lens as it forms in the mold is substantially reduced relative 
to that of conventional monomer-diluent systems which have been previously 
used in the ophthalmic art. 
The crosslinked polymer of this invention can be used for any application 
which could benefit from the optimum balance of properties it offers. 
Advantageously, the polymer is used for biomedical 
applications,.particularly for the fabrication of ophthalmic lenses, such 
as soft hydrogel contact lenses. 
DETAILED DESCRIPTION OF THE INVENTION 
The polyfunctional compound is a crosslinking agent containing at least two 
reactive polymerization sites. The number of reactive sites will depend on 
the particular saccharide chosen from which the compound is derived. The 
polymerization sites are preferably sites of ethylenic unsaturation, and 
each such site is preferably displayed at the terminus of a branch of the 
molecular chain of the compound. 
The compound can be a polyfunctional monomer or oligomer, but preferably it 
is a polyfunctional prepolymer which has a relatively high molecular 
weight in comparison to conventional crosslinking agents used for the 
preparation of ophthalmic lenses, such as EGDMA. Preferably, the number 
average molecular weight of such a prepolymer is between about 700 to 
about 50,000. The most preferred number average molecular weight is 
between about 9,000 to about 20,000. If the molecular weight of the 
prepolymer were less than about 700, then the crosslink density obtained 
when the prepolymer is polymerized with the hydrophilic monomer to form 
the crosslinked polymer may be undesirably high. This increased crosslink 
density could adversely reduce the water content of the swollen polymer, 
and hence its oxygen permeability. Additionally, the polymer may exhibit a 
decreased elongation with an undesirable increase in its brittleness. With 
respect to molecular weights greater than about 50,000, although it is 
possible to use prepolymers with these higher molecular weights, it may be 
difficult to process such prepolymers for the preparation of desired 
ophthalmic lenses. 
For the purpose of defining this invention, a "saccharide residue" is a 
residue of a monosaccharide, an oligosaccharide, or a polysaccharide. 
Preferably, the saccharide residue is a monosaccharide or oligosaccharide 
with 1 to 6, inclusive, more preferably 1 to 5, inclusive, more preferably 
1 to 3, inclusive, sugar units. Examples of some of the preferred 
saccharides which can be used are set forth in European Patent Application 
394,496, published Oct. 31, 1990, incorporated by reference herein. The 
most preferred saccharide residues are derived from monosaccharides and 
disaccharides. Of these, the most preferred are glucose and sucrose. 
Polysaccharides can also be used for preparing the polyfunctional 
prepolymer. In addition, carboxyl-containing polysaccharides can be used. 
Examples of these include alginic acid, pectin, and certain 
glucosaminoglycans. Also, saccharides such as maltose, lactose, 
methyl-.beta.-D-galactoside or methy-.beta.-D-galactopyranoside and 
methylated deoxyribose, can be used. 
In addition to the saccharide residue, the preferred polyfunctional 
prepolymers of this invention not only have a relatively high molecular 
weight in comparison to conventional crosslinking agents, but also contain 
a plurality of carbamate or carbamide residues. For the purpose of 
defining this invention, these carbamate or carbamide residues may be 
represented by the following formula: 
##STR1## 
The preferred polyfunctional prepolymers are represented by the following 
formula: 
EQU S--(A).sub.n !.sub.y 
wherein 
S is the residue of a five or six membered saccharide ring; 
A=--(CH.sub.2).sub.b --O--R.sub.2 --(R.sub.3).sub.c --(R.sub.4).sub.t 
--(CONH--R.sub.5)hd u 
n is between 2 and 4, inclusive; 
y is between 1 and 4, inclusive; 
b is 0 or 1; provided that for at least one A, b is 1; 
c is 0 or 1; 
R.sub.2 =(CH.sub.2 CHR.sub.6 O).sub.x H; 
R.sub.6 is hydrogen or methyl 
x is between 8 and 250, inclusive; 
R.sub.3 =--CONH--R.sub.7 --NHOC--; 
R.sub.7 is a divalent radical; 
R.sub.4 =--(CH.sub.2 (CHR.sub.6).sub.a X).sub.z CH.sub.2 (CHR.sub.6).sub.a 
X when c is 1, or alternatively, 
R.sub.4 =--O--R.sub.8 when u is 0; 
t is 0 or 1; 
X=0 or NH; 
a is between 0 and 3, inclusive; 
z is between 10 and 180, inclusive; 
R.sub.8 =C(R.sub.9).sub.3 C(R.sub.9).sub.2 !.sub.d (CH.sub.2).sub.e 
(OCH.sub.2 CHR.sub.6).sub.f ; 
R.sub.9 =H or F; 
d is between 0 and 30, inclusive; 
e is between 1 and 69, inclusive; 
f is between 0 and 50, inclusive; 
R.sub.5 is a free radical reactive end group; and 
u is 0 or 1, provided that u is 0 only when c and t each equal 0, and 
provided further that for at least one A, u is 1. 
Preferably, S is the residue of a sucrose or glucose ring; n is 3 or 4, 
preferably 4; y is between 1 and 3, inclusive, preferably 1 or 2; c is 1; 
and x is between 15 and 125, inclusive, preferably between 25 and 60, 
inclusive. In the preferred embodiment, R.sub.7 is the residue of 
isophorone diisocyanate (IPDI) or toluene diisocyanate (TDI); and R.sub.5 
is the residue of styrene isocyanate, isocyanatoethyl methacrylate, or the 
reaction product of HEMA with IPDI or TDI. In one preferred embodiment, 
when c equals 1, a is 1 or 2, preferably 1; and z is between 25 and 145, 
inclusive, preferably between 80 and 120, inclusive. In another preferred 
embodiment, when c equals 0, d is between 0 and 16, inclusive, preferably 
0; e is between 15 and 50, inclusive, preferably 21 and 33, inclusive; and 
f is 0. 
The most preferred prepolymers are those described in copending application 
U.S. Ser. No. 777,767, filed Oct. 15, 1991, now U.S. Pat. No. 5,196,458, 
issued Mar. 23, 1993 incorporated by reference herein. The preferred 
prepolymers are prepared by reacting an ethoxylated or propoxylated 
glucose or sucrose with a capped, free radical reactive isocyanate. The 
free radical reactive isocyanate is capped by first reacting a free 
radical reactive isocyanate with PEG or PPG, and then further reacting 
this intermediate with a diisocyanate. 
For the purpose of defining this invention, a "hydrophilic monomer" refers 
to any monomer or mixture of monomers which, when polymerized, yields a 
hydrophilic polymer capable of forming a hydrogel when contacted with 
water. Examples of hydrophilic monomers include, but are not limited to, 
hydroxy esters of acrylic or methacrylic acid, DMA, NVP, styrene sulfonic 
and carboxylic acids, and other hydrophilic monomers known in the art. 
Examples of hydroxy esters of acrylic or methacrylic acid include HEMA, 
hydroxyethyl acrylate, glyceryl methacrylate, hydroxypropyl methacrylate, 
hydroxypropyl acrylate and hydroxytrimethylene acrylate. The preferred 
hydroxyester is HEMA. 
The most preferred hydrophilic monomers are those derived from the reaction 
product of a free radical reactive monoisocyanate with a monoalkoxy 
polyalkylether. The polyalkyl ether is desirably a polyalkylene glycol, 
such as PEG or PPG, or a polyalkylene glycol with amino terminals. The 
free radical reactive monoisocyanate can be any monoisocyanate with a 
polymerizable ethylenic functionality. Examples of such isocyanates 
include isocyanatoethyl methacrylate (IEM), styrene isocyanate, and the 
reaction product of HEMA with either isophorone diisocyanate (IPDI) or 
toluene diisocyanate (TDI). To simplify the description of this invention, 
these preferred hydrophilic monomers will be referred to as "monocapped 
PEG". 
Monocapped PEG are the preferred hydrophilic monomers because such monomers 
provide outstanding physical properties to the crosslinked polymer in 
conjunction with the polyfunctional prepolymer acting as the crosslinking 
agent. Specifically, these hydrophilic monomers contribute significantly 
to increasing the modulus of the crosslinked polymer without sacrificing 
elongation. The use of these monomers appreciably contributes to the 
fabrication of ophthalmic lenses exhibiting high oxygen permeability and 
reduced brittleness. 
The preferred monocapped PEG monomers are represented by the following 
formula: 
EQU CH.sub.3 (CH.sub.2).sub.w O(CH.sub.2 CHR.sub.10).sub.v CONHR.sub.11 
wherein 
w is between 0 and 20, inclusive; 
v is between 20 and 135, inclusive; 
R.sub.10 is hydrogen or methyl; and 
R.sub.11 is represented by any of the following: 
##STR2## 
The most preferred monocapped PEGs are represented when v is between 85 and 
110, inclusive; w is between 0 and 3, inclusive; R.sub.10 is hydrogen; and 
R.sub.11 is represented by the following formula: 
##STR3## 
The most preferred monounsaturated polyalkylether is the reaction product 
of IEM with methoxyPEG because it is relatively easy to synthesize. 
In the preferred embodiment of the invention, the hydrophilic monomer is a 
mixture of hydrophilic monomers. The preferred mixture is a mixture of 
monocapped PEG with DMA. The weight ratio of monocapped PEG to DMA in the 
hydrophilic monomer mixture is desirably between about 1.5:1 to about 4:1, 
preferably between about 1.5:1 to about 2.5:1. In addition, it may be 
desirable to add a minor amount of HEMA to the hydrophilic monomer 
mixture. 
The hydrophilic monomers are preferably copolymerized with comonomers in a 
monomer reaction mixture to impart specific improvements in chemical and 
physical properties, depending on the particular application desired. For 
example, the equilibrium water content of an ophthalmic lens can be 
increased if MAA is used as a comonomer. Similarly, other components may 
be added for specific applications, for example, to impart UV absorbent or 
handling, enhancement or cosmetic tint properties to the finished lens. 
In a particularly preferred embodiment, a fluorinated monomer is added as a 
coreactant in the reaction mixture. The preferred class of fluorinated 
monomers are those derived from the reaction product of a free radical 
reactive monoisocyanate with a fluorinated alcohol. The fluorinated 
alcohol is preferably a monohydric alcohol, preferably an aliphatic 
alcohol. The preferred monohydric aliphatic alcohol is a C.sub.6-30 
alcohol. The most preferred fluorinated alcohol is perfluorooctanol. With 
respect to the free radical reactive monoisocyanate, it can be any of the 
monoisocyanates described previously. However, the most preferred of these 
is IEM, and so therefore the most preferred fluoromonomer is the reaction 
product of IEM with perfluorooctanol. 
Advantageously, the amount of fluorinated monomer added to the reactive 
monomer mixture is between about 2 to about 9 weight percent of reactive 
components, preferably between about 5 to about 7. The incorporation of 
the fluorinated monomer is particularly desired for the fabrication of 
ophthalmic lenses because the fluorinated monomer decreases the surface 
energy of the finished lens to improve its resistance to deposition of 
ocular tear components, such as lipids and proteins. If the amount of 
fluorinated monomer added to the reaction mixture were less than about 2 
percent, then the decrease in surface energy of a finished ophthalmic lens 
may not be realized. Conversely, if the amount of fluorinated monomer were 
greater than about 9 percent, then the optical characteristics of a 
finished lens may diminish, and the water content may drop as well. 
In another preferred embodiment, a second crosslinking agent is added to 
the reaction mixture to further increase the modulus of a finished 
ophthalmic lens derived from the crosslinked polymer. Although this 
crosslinking agent can be any polyunsaturated monomer, such as EGDMA, it 
preferably has a number average molecular weight between about 500 to 
about 2000 preferably about 750-1500. The preferred crosslinking agent is 
derived from the reaction product of an aromatic or cycloaliphatic polyol, 
e.g. bisphenol A, with a free radical reactive monoisocyanate, e.g. IEM. 
Its concentration in the reactive mixture is between about 5 to about 25 
weight percent of the reactive compounds, preferably about 13 to about 17 
percent. A concentration less than about 5 percent may fail to increase 
the lens modulus, and a concentration greater than about 25 percent may 
negatively impact water content. 
In another embodiment, it may be desirable to add fluorinated analogs of 
the hydrophilic monomers described above, and organosilicone monomers, to 
the reaction mixture to further enhance properties. Examples of these 
monomers are given in U.S. Pat. No. 5,034,461, incorporated by reference 
herein. 
The monomer reaction mixture also includes an initiator, usually from about 
0.05 to 1 percent of a free radical initiator which is thermally 
activated. Typical examples of such initiators include lauroyl peroxide, 
benzoyl peroxide, isopropyl percarbonate, azobisisobutyronitrile and known 
redox systems such as the ammonium persulfate-sodium metabisulfite 
combination and the like. Irradiation by ultraviolet light, electron beam 
or a radioactive source may also be employed to initiate the 
polymerization reaction, optionally with the addition of a polymerization 
initiator, e.g. benzoin and its ethers, as well as charge transfer 
initiators such as benzophenone/amine systems known in the art. 
The amount of the polyfunctional compound which is copolymerized with the 
hydrophilic monomer and other coreactants, if any, depends on numerous 
factors. This amount can be readily determined empirically. The amount 
chosen will depend on the molecular weight of the polyfunctional compound, 
its degree of functionality, and the final properties of the crosslinked 
polymer desired. When the polyfunctional compound chosen is a prepolymer 
having molecular weight between 9,000 and 20,000, and contains a glucose 
or sucrose residue, then the concentration of prepolymer in the reaction 
mixture is desirably between about 0.002 to about 0.020 moles prepolymer 
per 100 grams of reactive monomer components, more preferably between 
about 0.003 to about 0.0045 moles prepolymer per 100 grams of reactive 
monomer components. 
The polymerization of the reactive monomer mixture to form the crosslinked 
polymer is conveniently carried out in the presence of an inert diluent. 
The selection of a suitable diluent is important to solubilize the 
reactive components of the mixture, particularly those monomeric 
components which have relatively high molecular weights. Suitable diluents 
for the polymerization of the reactive monomers described herein are 
disclosed in U.S. Pat. No. 4,889,664. The preferred diluents are the boric 
acid esters of dihydric alcohols. The most preferred boric acid esters are 
those esters of polyethylene glycols, specifically, the boric acid ester 
of polyethylene glycol 400. The preferred amount of the boric acid ester 
of polyethylene glycol is between about 25 to about 65 weight percent of 
the reactive components, and the most preferred amount is between 35 to 50 
weight percent. 
For purposes of describing this invention, an "ophthalmic lens" is any lens 
adapted for placement on the cornea or in the eye. Examples of such lenses 
include scleral lenses, contact lenses, intraocular lenses, and corneal 
bandage lenses. The most preferred ophthalmic lens is a contact lens. The 
most preferred contact lens is a soft hydrogel lens. A hydrogel lens can 
be prepared by swelling the crosslinked polymer of this invention, which 
has been shaped in the form of the lens, with a significant amount of 
water. 
The preferred methods for forming the desired lens in the presence of a 
suitable inert diluent include the well known methods of centrifugal 
casting and cast molding, for example using molds described in U.S. Pat. 
No. 4,568,348. 
When the polymerization reaction to prepare the lens is sufficiently 
complete, the lens can be hydrated to its equilibrium water content. 
Preferably, the water content of the lens will range from about 35 to 
about 85 weight percent, more preferably from about 55 to about 75 weight 
percent. This range is considered ideal for extended wear applications 
where patient comfort, corneal health and handling characteristics are 
critical properties. 
The following examples set forth the most preferred embodiments of this 
invention. These examples are illustrative only, and should not be 
interpreted to limit the scope of this invention as set forth in the 
appended claims. Numerous additional embodiments within the scope and 
spirit of the claimed invention will become readily apparent to those 
skilled in the art upon a detailed review of this specification. 
Test Method 1 
Oxygen Permeability (Dk) 
The oxygen permeability through the lens is expressed as the Dk value 
multiplied by 10.sup.-11, in units of cm.sup.2 ml O.sub.2 /s ml mm Hg. It 
is measured using a polagraphic oxygen sensor consisting of a 4 mm 
diameter gold cathode and silver-silver chloride ring anode. 
Test Method 2 
Tensile Properties (Modulus, Elongation and Strength) 
The lens to be tested is cut to the desired specimen size and shape and the 
cross-sectional area measured. The specimen is then attached into the 
upper grip of a constant rate-of-crosshead-movement type of testing 
machine equipped with a load cell. The crosshead is lowered to the initial 
gauge length and the specimen attached to the fixed grip. The specimen is 
then elongated at a constant rate of strain and the resulting 
stress-strain curve is recorded. The elongation is expressed in percent 
and the tensile modulus and strength is expressed in psi (pounds per 
square inch). 
Test Method 3 
Gravimetric Water Content (Equilibrium Water Content-EWC) 
Flat discs are made which weigh approximately 5-8 grams. These discs are 
equilibrated in physiological saline, weighed and then dehydrated and 
weighed. gravimetric water content is expressed as a percent difference 
after a constant weight is recorded.

EXAMPLE 1 
Synthesis of Glucam E-20-polyethylene glycol (PEG) 1000) 
A total of 100 g (0.100 mol) of dry PEG 1000 is placed into a 1L three neck 
flask equipped with mechanical agitation, and gas-inlet tube. The system 
is flushed with dry nitrogen and then dry oxygen. To the PEG 1000 are 
added 375 g of dry acetonitrile and allowed to mix until the PEG 1000 has 
completely dissolved. Subsequently, 2 drops of Stannous Octoate and 500 
ppm MEHQ are added. Via a dropping funnel are added 15.20 g (0.098 mol) of 
isocyanatoethyl methacrylate. The reaction is allowed to proceed at room 
temperature for 24-28 hours. The progress of the reaction is followed by 
the disappearance of the NCO absorption at 2270 cm.sup.-1 in the infrared 
spectra. When the peak at 2270 cm.sup.-1 has completely gone the above 
reaction mixture is transferred to a dropping funnel. The contents of the 
dropping funnel are slowly added to a solution containing 200 g of dry 
acetonitrile and 17.42 g (0.100 mol) of 2,4-toluene diisocyanate. The 
reaction is again followed by infrared noting the reduction followed by 
the disappearance of the hydroxyl peak at around 3400 cm.sup.-1. To the 
above mixture are added 27.5 g (0.025 mol) of Glucam E-20. After the 
adsorption at 2270 cm.sup.-1 has gone the acetonitrile is removed under 
reduced pressure and the resultant white waxy solid Glucam E-20 PEG 1000 
is used as is. 
EXAMPLE 2 
A blend is prepared using 94.60% hydroxyethyl methacrylate (HEMA), 5.0% of 
the Glucam E-20 PEG 1000 prepared in Example 1, and 0.40% Darocur 1173 The 
above blend is mixed at 40.degree. C. for thirty minutes under reduced 
pressure (&lt;10 mm Hg) then transferred to a contact lens mold. The filled 
mold is exposed to UV light (wavelength 300-380nm, Dose=1.2-1.6 
Joules/cm.sup.2) for twenty minutes at approximately 60.degree. C. The 
lens molds are then separated and placed into distilled water at 
50.degree. C. for three to four hours. After the initial hydration period 
the lenses are allowed to equilibrate in physiological saline. The lenses 
are now tested according to test methods 1,2, and 3, respectively. 
EXAMPLE 3 
Contact lenses arm made from a blend composed of 84.60% HEMA, 15.00% of the 
Glucam E-20 PEG 1000, and 0.40% Darocur 1173. This blend is treated 
analogously to that of Example 2 and tested according to test methods 1,2, 
and 3, respectively. 
EXAMPLE 4 
Contact lenses are made from a blend composed of 74.60% HEMA, 25.00% of the 
Glucam E-20 PEG 1000, and 0.40% Darocur 1173. This blend is treated 
analogously to that of Example 2 and tested according to test methods 1,2, 
and 3, respectively. 
EXAMPLE 5 
Contact lenses are made from a blend composed of 4.60% HEMA, 35.00% of the 
Glucam E-20 PEG 1000, and 0.40% Darocur 1173. This blend is treated 
analogously to that of Example 2 and tested according to test methods 1,2, 
and 3, respectively. 
TABLE 1 
______________________________________ 
Properties of Soft Hydrogel Contact Lenses 
% 
Example # 
GluPEG1000 
% EWC Modulus 
Elongation 
Tensile 
Dk 
______________________________________ 
Example 2 
5 46 90 190 101 25 
Example 3 
15 51 92 160 103 27 
Example 4 
25 54 98 170 104 31 
Example 5 
35 56 104 160 107 32 
______________________________________ 
As can be seen from Table 1, as the Glucam E-20 PEG 1000 derivative is 
increased, the water content, modulus, and oxygen permeability of the lens 
increase. 
EXAMPLE 6 
(Synthesis of Glucam P-20 derivative) 
A total of 200 g (0.1515 mol) of dry Glucam P-20 is placed into a 1L three 
neck flask equipped with mechanical agitation, and gas-inlet tube. The 
system is flushed with dry nitrogen and then dry oxygen. To the Glucam 
E-20 are added 600 g of dry acetonitrile and allowed to mix until the 
Glucam P-20 has completely dissolved. Subsequently, 2 drops of stannus 
octoate and 500 ppm MEHQ are added. Via a dropping funnel are added 42.91 
g (0.277 mol) of isocyanatoethyl methacrylate. The reaction is allowed to 
proceed at room temperature for 24-28 hours. The progress of the reaction 
is followed by the disappearance of the NCO absorption at 2270 cm.sup.-1 
in the infrared spectra. The acetonitrile is removed under reduced 
pressure and the viscous Glucam P-20 derivative is used as is. 
EXAMPLE 7 
A blend is prepared using 94.60% hydroxyethyl methacrylate (HEMA), 5.0% of 
the Glucam P-20 derivative prepared in Example 6, and 0.40% Darocur 1173 
The above blend is mixed at 40.degree. C. for thirty minutes under reduced 
pressure (&lt;10 mm Hg) then transferred to a contact lens mold. The filled 
mold is exposed to UV light (wavelength 300-380nm, Dose =1.2-1.6 
Joules/cm.sup.2) for twenty minutes at approximately 60.degree. C. The 
lens molds are then separated and placed into distilled water at 
50.degree. C. for three to four hours. After the initial hydration period 
the lenses are allowed to equilibrate in physiological saline. The lenses 
are now tested according to test methods 1,2, and 3, respectively. 
EXAMPLE 8 
Contact lenses are made from a blend composed of 84.60% HEMA, 15.00% of the 
Glucam P-20 derivative. This blend is treated analogously to that of 
Example 7 and tested according to test methods 1,2, and 3, respectively. 
EXAMPLE 9 
Contact lenses are made from a blend composed of 74.60% HEMA, 2D.00% of the 
Glucam P-20 derivative. This blend is treated analogously to that of 
Example 7 and tested according to test methods 1,2, and 3, respectively. 
EXAMPLE 10 
Contact lenses are made from a blend composed of 59.60% HEMA, 40.00% of the 
Glucam P-20 derivative. This blend is treated analogously to that of 
Example 7 and tested according to test methods 1,2, and 3, respectively. 
TABLE 2 
______________________________________ 
Properties of Soft Hydrogel Contact Lenses 
% GLU 
Example # 
P-20 Der % EWC Modulus 
Elongation 
Tensile 
Dk 
______________________________________ 
Example 7 
5 42 71 150 98 11 
Example 8 
15 41 79 170 100 12 
Example 9 
25 40 85 160 91 9 
Example 10 
40 38 98 155 110 8 
______________________________________ 
As can be seen from Table 2, as the Glucam P-20 derivative is increased, 
the water content and Dk decrease and the modulus increases. 
EXAMPLE 11 
(Synthesis of Glucam E-20-polyethylene glycol (PEG) 4500) 
A total of 100 g (0.0220 mol) of dry PEG 4500 is placed into a 1L three 
neck flask equipped with mechanical agitation, and gas-inlet tube. The 
system is flushed with dry nitrogen and then dry oxygen. To the PEG 4500 
are added 375 g of dry acetonitrile and allowed to mix until the PEG 4500 
has completely dissolved. Subsequently, 2 drops of Stannous Octoate and 
500 ppm MEHQ are added. Via a dropping funnel are added 3.41 g (0.022 mol) 
of isocyanatoethyl methacrylate. The reaction is allowed to proceed at 
room temperature for 24-28 hours. The progress of the reaction is followed 
by the disappearance of the NCO absorption at 2270 cm.sup.-1 in the 
infrared spectra. When the peak at 2270 cm.sup.-1 has completely 
disappeared the above reaction mixture is transferred to a dropping 
funnel. The contents of the dropping funnel are slowly added to a solution 
containing 200 g of dry acetonitrile and 3.83 g (0.0220 mol) of 
2,4-toluene diisocyanate. The reaction is again followed by infrared 
noting the reduction followed by the disappearance of the hydroxyl peak at 
around 3400 cm.sub.-1. To the above mixture are added 6.0 g (0.006 mol) of 
Glucam E-20. After .the adsorption at 2270 cm.sup.-1 has disappeared the 
acetonitrile is removed under reduced pressure and the resultant white 
waxy Glucam E-20 PEG 4500 solid is used as is. 
EXAMPLE 12 
(Synthesis of Inert Diluent PEG 400 BAE (boric acid ester)) 
A total of 400 g (1 mol) of polyethylene glycol 400 (PEG 400) is placed 
into a 2L rotary evaporator flask. To the above flask are added 108.2 g 
(1.75 mol) of boric acid. The flask is placed on a rotary evaporator and 
the pressure is slowly reduced (&lt;0.05-1 mm Hg). After full vacuum is 
established the temperature of the bath is slowly raised to 92.degree. C. 
Water is recovered from the reaction as the boric acid ester is formed. 
The clear viscous liquid PEG 400 BAE is used as is. 
EXAMPLE 13 
A blend is prepared using 58.56% hydroxyethyl methacrylate (HEMA), 1.20% of 
the Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 
40% of the inert diluent PEG 400 BAE prepared in Example 12. The above 
blend is mixed at 40.degree. C. for thirty minutes udder reduced pressure 
(&lt;10 mm Hg) then transferred to a contact lens mold. The filled mold is 
exposed to UV light (wavelength=300-380nm, Dose=1.2-1.6 Joules/cm.sup.2) 
for twenty minutes at approximately 60.degree. C. The lens molds are then 
separated and placed into distilled water at 50.degree. C. for three to 
four hours. After the initial hydration period the lenses are allowed to 
equilibrate in physiological saline. The lenses are now tested according 
to test methods 1,2, and 3, respectively. 
EXAMPLE 14 
Contact lenses are made from a blend composed of 55.56% HEMA, 4.20% of the 
Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 40% 
of the inert diluent prepared in Example 12. This blend is treated 
analogously to that of Example 13 and tested according to test methods 
1,2, and 3, respectively. 
EXAMPLE 15 
Contact lenses are made from a blend composed of 55.56% HEMA, 6.60% of the 
Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 40% 
of the inert diluent prepared in Example 12. This blend is treated 
analogously to that of Example 13 and tested according to test methods 
1,2, and 3, respectively. 
EXAMPLE 16 
Contact lenses are made from a blend composed of 45.36% HEMA, 14.40% of the 
Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 40% 
of the inert diluent prepared in Example 12. This blend is treated 
analogously to that of Example 13 and tested according to test methods 
1,2, and 3, respectively. 
EXAMPLE 17 
Contact lenses are made from a blend composed of 36.36% HEMA, 23.40% of the 
Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 40% 
of the inert diluent prepared in Example 12. This blend is treated 
analogously to that of Example 13 and tested according to test methods 
1,2, and 3, respectively. 
EXAMPLE 18 
Contact lenses are made from a blend composed of 29.76% HEMA, 23.40% of the 
Glucam E-20 PEG 4500 prepared in Example 11, 0.24% Darocur 1173, and 40% 
of the inert diluent prepared in Example 12. This blend is treated 
analogously to that of Example 13 and tested according to test methods 
1,2, and 3, respectively. 
TABLE 3 
______________________________________ 
Properties of Soft Hydrogel Contact Lenses 
% % Elon- 
Example # 
GLUPEG 4500 
EWC Modulus 
gation 
Tensile 
Dk 
______________________________________ 
Example 13 
2 40 48 189 79 12 
Example 14 
7 49 52 145 77 14 
Example 15 
11 54 58 171 82 19 
Example 16 
24 65 59 130 77 27 
Example 17 
39 72 74 131 86 34 
Example 18 
50 76 89 105 81 39 
______________________________________ 
As can be Seen in Table 3, as the Glucam E-20 PEG 4500 derivative increases 
the EWC, modulus, and Dk increase. 
EXAMPLE 19 
(Synthesis of dicapped Bis Phenol A (BPA) 890). 
A total of 200 g (0.345 mol) of dry Photonol 7025 is placed into a 1L three 
neck flask equipped with mechanical agitation, and gas-inlet tube. The 
system is flushed with dry nitrogen and then dry oxygen. To the BPA are 
added 375 g of dry acetonitrile and allowed to mix until the BPA has 
completely dissolved. Subsequently 2 drops of stannous octoate and 500 ppm 
MEHQ are, added. Via a dropping funnel are added 107.1 g (0.690 mol) of 
isocyanatoethyl methacrylate. The reaction is allowed to proceed at room 
temperature for 24-28 hours. The progress of the reaction is followed by 
the disappearance of the NCO absorption at 2270 cm.sup.-1 in the infrared 
spectra. The acetonitrile is removed under reduced pressure, and the 
resultant viscous liquid dicapped SPA 890 is used as is. 
EXAMPLE 20 
(Synthesis of Fluoro Monomer (FM)) 
A total of 200 g (0.050 mol) of dry 
2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluoro-1-octanol is placed into a 
1L three neck flask equipped with mechanical agitation, and gas-inlet 
tube. The system is flushed with dry nitrogen and then dry oxygen. To this 
fluoro alcohol are added 375 g of dry acetonitrile and allowed to mix for 
fifteen minutes. Subsequently, 2 drops of stannous octoate are added to 
the acetonitrile/2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluoro-1-octanol 
mixture. Via a dropping funnel are added 15.52 g (0. 100 mol) of 
isocyanatoethyl methacrylate. The reaction is allowed to proceed at room 
temperature for 24-28 hours. The progress of the reaction is followed by 
the disappearance of the NCO absorption at 2270 cm.sup.-1 in the infrared 
spectra. The acetonitrile is removed under reduced pressure and the 
resultant white waxy fluoromonomer is used as is. 
EXAMPLE 21 
(Synthesis of monocapped monomethoxy polyethylene glycol (mPEG) 2000) 
A total of 200 g (0.10 mol) of dry mPEG 2000 is placed into a 1L three neck 
flask equipped with mechanical agitation, and gas-inlet tube. The system 
is flushed with dry nitrogen and then dry oxygen. To this mPEG 2000 are 
added 600 g of dry acetonitrile and allowed to mix until the mPEG 2000 has 
completely dissolved. Subsequently, 2 drops of stannous octoate and 500 
ppm MEHQ awe added. Via a dropping funnel are added 15.51 g (0.10 mol) of 
isocyanatoethyl methacrylate. The reaction is allowed to proceed at room 
temperature for 24-28 hours. The progress of the reaction is followed by 
the disappearance of the NCO absorption at 2270 cm.sup.-1 in the infrared 
spectra. The acetonitrile is removed under reduced pressure and the white 
waxy monocapped mPEG 2000 is used as is. 
EXAMPLE 22 
A blend is prepared using 9.36% hydroxyethyl methacrylate (HEMA), 21.0% of 
the Glucam E 20 PEG 4500 prepared in Example 11, 15% of the mPEG 2000 
prepared in Example 21, 10.2% of the BPA 890 prepared in Example 19, and 
4.20% of the fluoromonomer prepared in example 20, 0.24% Darocur 1173, and 
40% of the inert diluent prepared in Example 12. The above blend is 
maintained at 40.degree. C. for thirty minutes under reduced pressure (&lt;10 
mm Hg) then transferred to a contact lens mold. The filled mold is exposed 
to UV light (wavelength=300-380nm, Dose=1.2-1.6 Joules/cm.sup.2) for 
twenty minutes at approximately 60.degree. C. The lens molds are then 
separated and placed into distilled water at 50.degree. C. for three to 
four hours. After the initial hydration period the lenses are allowed to 
equilibrate in physiological saline. The lenses are now tested according 
to test methods 1,2, and 3, respectively. 
EXAMPLE 23 
A blend is prepared using 3.36% hydroxyethyl methacrylate (HEMA), 21.0% of 
the Glucam E-20 PEG 4500 prepared in Example 11, 21.0% of the mPEG 2000 
prepared in Example 21, 10.2% of the BPA 890 prepared in Example 19, and 
4.20% of the fluoromonomer prepared in Example 20, 0.24% Darocur 1173, and 
40% of the inert diluent prepared in Example 12. The above blend is 
maintained at 40.degree. C. for thirty minutes under reduced pressure (&lt;10 
mm Hg) then transferred to a contact lens mold. The filled mold is exposed 
to UV light (wavelength=300-380nm, Dose=1.2-1.6 Joules/cm.sup.2) for 
twenty minutes at approximately 60.degree. C. The lens molds are then 
separated and placed into distilled water at 50.degree. C. for three to 
four hours. After the initial hydration period the lenses are allowed to 
equilibrate in physiological saline. The lenses are now tested according 
to test methods 1,2, and 3, respectively. 
TABLE 4 
______________________________________ 
Properties of Soft Hydrogel Contact Lenses 
Example # 
% EWC Modulus Elongation 
Tensile 
Dk 
______________________________________ 
Example 22 
73 91 118 125 49 
Example 23 
77 101 125 122 55 
______________________________________ 
As can be seen from Table 4, various combinations of the monomers and 
crosslinkers disclosed within will give contact lens materials with 
superior oxygen permeability and mechanical properties.