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LE Magazine February 2003
Preserving Clear Vision
When aging individuals are asked what
they fear most, one of the most frequently cited concerns is
going blind or having a major loss of vision. Elderly people
encounter staggeringly high rates of cataract, glaucoma and
macular degeneration.
The good news is that degenerative eye
disease is not inevitable. Scientific studies conclusively
show that the risk can be mitigated via lifestyle and
nutritional modifications. While major advances have been made
in treating ocular disorders, there are still technological
gaps that cause many to lose their precious vision. This
article reviews the published literature and reveals new
studies showing that common diseases of the eye are largely
preventable.
Cataract surgery is virtually a rite of
passage in aging Americans. Each year, 1.3 million cataractous
lenses are surgically removed and replaced with synthetic
lenses.1 The cost of all of these
procedures combined has been estimated to be at least 3.5
billion dollars.
With the aging of the American population,
it's likely that ophthalmologists who perform these surgeries
will find themselves becoming progressively busier as cataract
diagnoses climb in number. Cataract surgery has been perfected
to the point where it is often viewed as simple surgery
because complications are rare and recovery is generally
rapid. The facts are that it is actually a complex and
delicate surgery wherein things can and do go wrong during and
after the surgery. Complication rates can vary significantly
from surgeon to surgeon.
Even though complication rates are low, a
small fraction of 1.3 million surgeries results in a
significant number of people (about 26,000 to 28,000 people in
the U.S.) being affected. These unfortunate individuals
develop serious complications such as secondary glaucoma,
detached retinas, corneal edema, severely compromised corneas
requiring corneal transplants and internal eye infections that
can cause possible complete loss of the eye.2-9 These complications can mandate
hospitalization, and other major surgery to treat the
complication.
Twenty to thirty percent of people who
have cataracts removed and replaced with artificial lenses
develop opacifications (clouding) of the lens capsule. This
capsule was originally part of the patient's own lens but was
left in the eye to hold the newly implanted lens in the proper
position. Laser surgery is required to remove these
opacifications and restore clear vision.
Why cataract is so common
In most body tissues, new, healthy cells are constantly
replacing worn-out cells. The lens of the eye, however,
experiences no turnover of cells at all-which means that the
ones you have when you are born are the ones that you have to
last you your lifetime.
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Symptoms of Cataract
As the cataract progresses it
will lead to some or all of the following
symptoms:
- Altered color vision (people tell
you that your clothes are mismatched or your hair is
not its usual color, although you see the right colors
when you look in the mirror).
- Feeling of looking through a
clouded-over piece of glass.
- Increased sensitivity to glare
from the sun or oncoming headlights.
- Increasingly blurred vision.
- Need for progressively brighter
illumination in order to see clearly.
- Double vision when looking out of
only one eye (the other eye is covered).
- Difficulty seeing in the
dark.
- Vision that is brighter in one
eye than in the other.
You are more likely to have
cataracts if you:
- Have diabetes.
- Live in a sunny climate without
regular use of hat and UV-blocking sunglasses.
- Have had to use topical or
systemic steroid drugs.
- Have ever smoked heavily.
- Have generally poor
nutrition.
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The lens of the eye is composed mostly of protein and
water, which forms a structurally clear tissue allowing light
to pass through and focus on the retina. As we age the lens
continues to grow and become less transparent to light. Long
term photo (light) stress, oxidative stress, glycation and
other factors can lead to severe distortions in the lens fiber
proteins. The result is that proteins in the eye lens clump
(crosslink), become oversaturated with water (water influx),
and rupture in the cell fiber wall (bleb formation). All of
this structural damage to lens proteins eventually creates
opacity (inhibiting light transmission), which by definition
is a cataract.
At first, symptoms may be so mild that the visual changes
are attributed to a need for new glasses. Patients will often
seek help for their visual changes and will be given a new
pair of glasses, which will actually help because as the
cataract develops it will cause the lens to swell changing the
eyeglass prescription. Most doctors will not tell the patient
that they have cataracts at this stage. Therefore, you must
inform your doctor that you want to know about all lens
changes-even small ones.
What causes cataract
Exposure to ultraviolet (UV) radiation is a well-known risk
factor for cataract. Excessive UV exposure increases free
radical formation in the lens, and can outpace the body's
ability to subdue those damaging free radicals with
antioxidants. optometrists and ophthalmologists almost
universally recommend the use of wide-brimmed hats and
sunglasses during sun exposure to minimize the amount of UV
radiation that strikes the lens of the eye.
The link between poor nutrition and risk of cataract
formation has been illustrated in a large number of clinical
studies.10 A fair amount of
research has linked shortages of specific nutrients to
increased cataract risk, and shown that populations that
consume higher levels of those nutrients have reduced
risk.11,12 It is widely
acknowledged that elevated free radical stress is also at
least partially responsible for glaucoma and age-related
macular degeneration, two other leading causes of blindness in
aging individuals.
Diabetics are at particularly high risk for cataract. The
high blood sugar levels found in diabetics have a direct
effect on lens health, elevating oxidative stress and a
destructive process called glycation.
Glycation is the pathogoical binding of sugars to proteins,
which causes the resulting glycated proteins to produce 50
times more free radicals than non-glycated proteins. This
heightened oxidative stress works, in turn, to accelerate
glycation reactions-a vicious cycle. The end result of
uncontrolled glycation is rapid organ aging and increased risk
of a number of age-related diseases. Glycated proteins trigger
a process called crosslinking, where proteins become bound
together, causing them to become inflexible and less able to
function in physiological systems.
It is likely that glycation plays a role in aging in
non-diabetics as well, especially those who eat diets high in
sugars and refined carbohydrates or those who have blood
sugars higher than normal but not high enough to merit a
diabetes diagnosis.
Diabetes also causes increased activity of an enzyme called
aldose reductase, which encourages clouding of the lens. It
has been found that nutrients that inhibit the activity of
this enzyme-specifically, the flavonoid nutrient quercetin-may
slow the progression of diabetes-related cataracts.
Protecting the eye lens
A great deal is known today about the causes of cataract,
and significant progress has been made in the search for
inexpensive, non-invasive, low-risk methods to halt
cataractogenesis and prevent cataracts from forming. Such a
preventative therapy could help many aging people avoid
surgery altogether and protect the millions who don't have
access to surgery against blindness caused by cataract. There
could be an added benefit of prevention of other blinding eye
diseases, including glaucoma and age-related macular
degeneration.
Nutrients that have been shown effective at protecting
against cataract include carnosine, glutathione, taurine and
cysteine; the antioxidant vitamins C, A and E; and vitamin B2
(riboflavin). The following paragraphs describe how each of
these nutrients helps protect against loss of vision.
Carnosine
Carnosine is a free radical scavenger that is especially
protective against lipid peroxidation.13 Since cell membranes are primarily
comprised of fatty acids, carnosine helps maintain membrane
function and cellular structure.
Carnosine's best-known effect, however, is its ability to
prevent the formation of advanced glycated end products
(protein crosslinks). Carnosine competes with proteins for the
binding sites they would occupy on sugar molecules, making it
the best glycation preventative currently recognized in the
world of nutrition research.
Carnosine has been found to significantly extend the life
span of cultured cells and fruit flies, inhibit the toxic
effects of the protein that accumulates in the brains of
Alzheimer's patients, protect against the toxic effects of
copper- zinc in the brain and enhance the state of balance
(homeostasis) under which physiological systems work best.
And, finally, it has been shown to prevent and/or reverse
cataract.14,15
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When administered topically to the eye in the form of
N-acetyl-L-carnosine-(functionally, a time-release form of
carnosine), this dipeptide can move easily into both the
water-soluble (aqueous) and lipid-containing parts of the eye.
Once there, it helps to prevent DNA strand breaks induced by
UV radiation and enhances DNA repair.16 Once it has entered
the lipid areas of the eye, N-acetyl-L-carnosine partially
breaks down and becomes L-carnosine.
Chinese and Russian researchers have studied
cataract-preventive nutrients for nearly a decade. A Chinese
study done by A.M. Wang in 1999, used 96 patients aged 60
years or older having senile cataracts of various degrees of
maturity with the duration of the disease from 2 to 21 years.
Patients instilled one to two drops of the
carnosine-containing solution in each eye three to four times
each day for a period of treatment ranging from three to six
months. The level of eyesight improvement and the change of
lens transparency were considered as an evaluation index of
the curative effect of carnosine. The result showed that
carnosine gives a pronounced effect on primary senile
cataracts, the effective rate being 100%. For mature senile
cataracts, the effect rate was 80%.17
The Russians most recent contribution was published in 2002
in the journal Drugs Research and Development.18 In two separate studies, they applied
a one percent solution of N-acetyl-carnosine to the affected
eyes of cataract patients twice a day. Only patients with mild
cataracts-not anticipated to require surgery within the next
two years-in one or both eyes were selected to participate. A
matched control group received placebo drops, and another
small matched group received no drops at all. The first study
lasted six months, while the second continued for a total of
24 months. Tests of visual acuity and glare sensitivity were
administered every two months in the first study and every six
in the second.
After six months, a full 90% of eyes treated with
N-acetyl-carnosine showed improvements in visual acuity
ranging from 7% to 100%. Glare sensitivity improved 27% to
100% in 88.9% of carnosine recipients, and image analysis (a
measurement of visual clarity) improved in 41.5% of treated
eyes. Lens examination revealed fewer areas of lens opacity in
the posterior subcapsular region. No worsening of vision was
found in the eyes treated with N-acetylcarnosine, and all of
these benefits were sustained through the 24 months that
treatment continued.
These study results are evidence that N-acetyl-carnosine is
one of the most important nutrients for cataract prevention.
The entire body of research on carnosine reveals its promise
as an anti-aging nutrient that works at several levels to
protect multiple organ systems.
Glutathione
The concentration of glutathione in the lens of the eye is
higher than in most other tissues. It functions to protect the
structural proteins and enzymes necessary for the maintenance
of lens flexibility and clarity against free radical assault.
Aging lenses or lenses that are under oxidative stress lose
glutathione, and this shrinkage of the glutathione pool has
been found to lead directly to reactions that cause
crosslinking of proteins and lens opacification.19-26 L-carnosine and vitamin E have
been shown to protect and restore these levels of glutathione.
Oral supplements of NAC (n-acetyl-cysteine) and alpha lipoic
acid help increase tissue levels of glutathione in the
eye.
Taurine
High concentrations of taurine are needed within the eye to
maintain optimal function and structure. It has been found to
protect the lens against free radical damage.27,28 In a series of studies performed
by researchers at the University of Maryland,27 rat lenses
were cultured with a potent oxidant called menadione. The
addition of physiological amounts of taurine-enough to create
a concentration roughly equivalent to that which would exist
in healthy lenses-attenuated the harmful effects of the
oxidant. Another study found that the lenses of diabetic rats
were protected against cataract by physiological levels of
taurine.29
Vitamin C
Vitamin C protects the eye against damaging ultraviolet
radiation and has been found to reduce the risk of
cataracts.30 One study found that
the higher the vitamin C intake, the less likely cataract was
to develop. Women who used a vitamin C supplement for 10 years
or more enjoyed the most protection.31
Vitamin C naturally exists in high concentrations in the
aqueous humor (the fluid that fills the eyeball and filters
light as it passes through to the retina) and the corneal
epithelium (the outer layer of the front of the eyeball).
Published studies indicate that consuming high doses of
vitamin C orally provides substantial protection to your
eyes.32-34
Riboflavin
Also known as vitamin B2, riboflavin is responsible for
removing oxidized glutathione-glutathione that has been "used
up" in the process of buffering free radicals and has become a
free radical-bearing molecule itself-from the
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Alleviating
"Dry Eye"
Syndrome
A problem that affects people
as they age is the onset of dry eye symptoms. This
disorder is one of the leading causes for visits to the
optometrist and ophthalmologist. Dry eye can be a very
uncomfortable condition but generally does not lead to
serious eye complications. One of the best treatments
for dry eye symptoms is a good soothing eye drop. There
are numerous drops on the market, many of which have
toxic preservative systems that can actually make the
problem worse with continued use. Additionally, some of
these drops contain lubrication systems that will only
stay in contact with the corneal epithelium (the outer
layer of the cornea) for a few minutes. Most eye doctors
that are oriented toward prevention will recommend an
eye drop containing the lubricant glycerin and/or
carboxymethylcellulose sodium plus other nutrients such
as vitamin E, vitamin A, carnosine or glutathione. A
drop of this combination will provide significant relief
to dry, irritated eyes. It is estimated that 10% of all
adults and 18% of elderly adults suffer from discomfort
due to chronic eye dryness or irritation.* An eye drop
containing the above listed ingredients-used one to four
times daily will provide comfort and protection against
dry irritated eyes and will provide the nutritional
support needed by the aging eye.
*
Chibret H. Dry eyes syndrome: reality and perspectives
of treatment. Ann Pharm Fr 2002 Mar; 60(2):115-22.
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lens of the eye. Research published in the March 2000 issue
of the journal Ophthalmology posited a role for the B family
of vitamins as protectors against cataract,35 and a more recent epidemiological
study found a link between riboflavin supplementation and
decreased cataract risk.36 These new findings indicate that
the oral consumption of riboflavin, along with other B-complex
vitamins provides a considerable degree of protection against
common degenerative ocular disorders.
Vitamin A
Long known to be essential for proper eye development,
vitamin A continues to be important for the health of the eyes
throughout the human life span, particularly the retina.
Higher dietary intake of vitamin A has been found to decrease
cataract risk.36 It-along with
vitamin C and vitamin E-is also needed to regenerate oxidized
glutathione. Antioxidants work cooperatively, regenerating one
another as they are oxidized themselves in the process of
buffering free radicals.37 Vitamin
A has been used as a topical agent to treat contact lens
problems and external eye disorders for some years now.
Vitamin E
Several epidemiological studies have found that higher
intakes of vitamin E have a protective effect against
cataract.38 Low serum levels of
vitamin E correlate strongly with increased cataract
risk.39 Researchers at the
Institute of Biological Chemistry at the University of Catania
in Italy found that chronic administration of vitamin E
restored glutathione levels in aging rat lenses to those found
in young rats.40 A study by a
German research team found that vitamin E deficiency in the
lenses of rats worsened the damage done by exposure to
ultraviolet radiation.40
Looking at cataract prevention
Scientific findings continue to establish the benefits of
antioxidants and anti-glycating agents in the prevention and
treatment of cataract. For instance, research from the USDA
Human Nutrition Research Center on Aging has demonstrated that
antioxidants such as ascorbate, carotenoids and tocopherol,
may protect against cataract formation. A five-year study of
over 3000 Wisconsin residents, aged 43 to 86, showed that the
risk for cataract was 60% lower among people who reported
taking multivitamins or any supplement containing vitamin C or
E on a long-term basis (more than 10 years) compared to
non-users.32
While the evidence is compelling that individual nutrients
reduce cataract risk, a more comprehensive approach would
involve the oral ingestion of vitamin C, taurine, alpha lipoic
acid, cysteine and riboflavin along with the topical
application of carnosine, vitamin A and vitamin E directly
into the eye. Carnosine, vitamin A and vitamin E are also
important nutrients to ingest orally. More about this will
appear later.
Purchase Brite Eyes from the Life Extension Foundation
Continued on Page
2 of 2
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