Life Extension Magazine February 2003
Preserving Clear Vision
The macula is the central and most vital area of the retina. It records images and sends them via the optic nerve from the eye to the brain. The macula is responsible for focusing central vision that is needed for seeing fine detail, reading, driving and recognizing facial features.
Age-related macular degeneration is the leading cause of blindness in people over the age of 55, affecting more than 10 million Americans. It is a condition in which the central portion of the retina (the macula) deteriorates. It is equally common in men and women and more common in whites than blacks. The cause is unknown, but the condition tends to run in some families. Macular degeneration affects more Americans than cataracts and glaucoma combined.
There is little that can be done within conventional medical treatment protocols to restore lost eyesight with either form of the disease. Leading researchers, however, are documenting the benefits of a more holistic approach in the treatment of macular degeneration. Patients are being encouraged to increase physical fitness, improve nutrition (including a reduction in saturated fats), abstain from smoking and protect their eyes from sunlight. Dietary supplementation of trace elements, antioxidants and vitamins is recommended for improving overall metabolic and vascular functioning. Early screening and patient education offer the most hope for reducing the debilitating effects of the disease.
Exposures to sunlight and photochemical damage have been suspected factors in macular degeneration, as well as decreased antioxidant activity responsible for damage control.
An age-dependent drop in glutathione blood status and a significantly lower level of glutathione has been found in older individuals compared to younger ones. Moreover, an increase of oxidized glutathione by-product over time suggests more oxidation and the incumbent higher risk of age-related eye diseases.30 In the early stages of macular degeneration, glutathione has been found to protect retinal pigment epithelial cells from dying.41
Glutathione, which is particularly concentrated in the lens, has been shown to have a hydroxyl radical-scavenging function in lens epithelial cells.19
Other studies have been examining how antioxidant status relates to the risk of age-related macular degeneration. The Baltimore Longitudinal Study of Aging, for instance, found that tocopherol, and an antioxidant combination of tocopherol, carotene and ascorbate were protective. Researchers have also been looking at the potentially therapeutic role of individual compounds. For example, a study from Sete, France of 2584 inhabitants showed that higher plasma levels of alpha-tocopherol were inversely related to macular degeneration development and progression.43
The Age-Related Eye Disease Study Research Group43 has shown a protective effect against macular degeneration when higher doses of antioxidants and minerals are taken on a regular basis. The same can be said for cataracts as there is now ample evidence that indicate cataracts have in fact a nutritional connection. It, therefore, appears that prevention is the best solution to postponing or avoiding macular degeneration and cataract surgery. Most eye care professionals to date have told patients affected by these conditions that no treatment exists for macular degeneration and that surgery is the only treatment for cataracts. Emerging research, however, provides new hope for many of these individuals.
One of the leading complications associated with diabetes is blindness or other eye diseases stemming from vascular damage to the eyes caused by high blood sugar. Diabetic retinopathy, the most common form of diabetes eye conditions, is caused by damage of the retinal blood vessels. This damage causes the ruptured vessels to leak fluid, restricting oxygen and blurring sight. As the disease progresses, the eye tries to form new vessels on the surface of the retina, which may also bleed or obscure sight by their mere presence. Diligently controlling blood sugar is a major means of preventing or at least slowing the onset and progression of diabetic retinopathy.
In diabetics, the vitreous body of the eye has been found to change more rapidly than with just normal aging. These changes have been implicated in functional disturbances and retinal detachment. The vitreous body is composed of a fine network of hyaluronan gel, collagen, proteoglycans and fibronectin, all of which are susceptible to free radical damage brought on by light and UV damage and glycation.44
A growing body of research shows that oxidation induced by glycation can wreak havoc on the eye. Protein glycation occurs when sugar molecules inappropriately bind to protein molecules, forming crosslinks that distort the proteins and consequently render them useless. Glycation appears to increase oxidative processes, which may explain why both glycation and oxidation simultaneously increase with age. High blood sugar also increases glycation activity, which may also explain the various kinds of tissue damage that characterize advanced diabetes.
Even before an individual is officially diagnosed with Type II diabetes, high serum insulin levels can induce retinopathy. Overweight individuals at risk for Type II diabetes should have their fasting insulin levels checked to guard against a pre-diabetic state (characterized by hyperinsulinemia) that can severely damage the eyes. By following a low glycemic diet, excess serum insulin can be reduced. More on lowering excess insulin will be discussed in an upcoming issue of this publication, but those concerned with diabetic retinopathy can view a new protocol by logging on to www.lef.org and looking under the Health Concerns section for the Retinopathy protocol.
Glaucoma can result from the build-up of pressure in the aqueous humor, the liquid that fills the area between the cornea and the lens. Pressure build-up sometimes is not the whole story, as optic nerve damage can continue after pressure is returned to normal. It is thus critical to have an ophthalmologist check for optic nerve damage and not just abnormal intraocular pressures.
Age-related losses of antioxidants increase physical stress on the eye, and oxidative damage are underlying causes. For example, diminished antioxidant activity in lacrimal (tear) fluid and blood plasma seems to coincide with progression of glaucoma. It's also proposed that the rate of nerve damage increases as antioxidant capacity and protease activity declines with age.
Evidence is slowly mounting to support the potential effectiveness of antioxidants against glaucoma. A Russian study of 64 patients with primary open-angle glaucoma found that a combined regimen of hyperbaric oxygen and antioxidants over a five-year period stabilized visual function in 80% of patients.45
To read Life Extension's revised Glaucoma protocol, log on to www.lef.org. Click the Health Concerns button and scroll down to Glaucoma.
Preventing degenerative eye disease
Young eyes contain high concentrations of natural antioxidants that protect against cataract, macular degeneration and other ocular disorders. In the aged eye, synthesis of natural antioxidants such as glutathione is reduced, resulting in excessive free radical damage.
According to one published report, "nutritional intervention to enhance the glutathione antioxidant capacity may provide an effective way to prevent or treat age-related macular degeneration." Even glaucoma has been linked with reduced blood flow and increased levels of damaging free radicals.
Another problem with aging eyes is protein degradation and the formation of advanced glycation end products. Aged eyes fail to break down and remove old proteins, which results in the accumulation of non-functioning protein crosslinks. The resulting accumulation of damaged proteins leads to senile ocular diseases.
The antioxidant supplements consumed by Life Extension Foundation members have been shown to provide considerable protection against senile eye disorders. Unfortunately, aging diminishes circulation to the eye, thereby denying the eyes the full benefits of orally ingested antioxidant and anti-glycating agents.
The good news is that topical eye drop preparations are now available to provide some of the most important nutrients directly into the eye.
If people live long enough, severe visual impairment or blindness is almost inevitable. Few people know that poor vision from cataracts affects 80% of people 75 years of age and older.
The eyes are particularly vulnerable to the effects of aging. Degenerative changes in the eye often begin in middle age. By age 70, a significant percentage of people suffer from macular degeneration, glaucoma and/or cataract. Diabetic retinopathy is also a major cause of visual disability among adults.
A review of the published scientific literature shows that common ocular disorders can be prevented with lifestyle modifications such as following a low glycemic diet, wearing UV blocking sunglasses, avoiding excess saturated fat and not smoking.
A compelling body of evidence indicates that orally ingested antioxidants and anti-glycating agents (such as carnosine) help to prevent and treat eye disease.
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