Macular degeneration

Macular degeneration which is commonly known as age-related macular degeneration (AMD /ARMD), is a medical condition which can lead to blurred or weakness of vision in the center of the visual filed. This condition at the early stage often does not present any symptoms, however over time it causes gradual worsening of the vision which can make it hard to recognize faces, drive, read, or perform some other daily activities. Data from the National Institute of Health suggests that more Americans are affected by AMD than cataracts and glaucoma combined.

The macula is a highly pigmented yellow spot near the center of the retina of the human eye, providing us with the clearest, most distinct vision needed in reading, driving, seeing fine detail, and recognizing facial features. AMD is characterized by the deterioration of the macula which impairs central vision. Both forms of the disease may start from affecting one eye or both eyes simultaneously.

There are two forms of macular degeneration either atrophic (dry) or neovascular (wet). These conditions can be spotted during a regular eye exam. Dry AMD is observed in 80–90% of cases and tends to progress slowly. In 10–20% of people, dry AMD progresses to the wet type.

The "dry" form of macular degeneration shows itself by the presence of yellow deposits, called drusen, in the macula. A few small drusen may not cause changes in vision; but, as they progress in size and/or quantities, their symptoms become more noticeable In advanced stages of dry macular degeneration, the light-sensitive layer of cells in the macula is thinning as well, which leads to atrophy, or tissue death resulting in development of blind spots in the center of the vision.

The "wet" form of macular degeneration is the result of the abnormal growth of the blood vessels underneath the macula. These blood vessels leak blood and fluid into the retina, causing distortion of vision, such as when the straight lines look wavy, or blind spots and loss of central vision. These abnormal blood vessels and their bleeding eventually form a scar and damage the surrounding tissues.

What are the Risk Factors or Causes for Macular Degeneration?

Macular degeneration typically occurs in older ages. Genetic factors and ethnicity play roles, for example AMD is more seen in Americans than African-Americans. Vascular diseases (including cardiovascular disease), hypertension (high blood pressure), smoking, Photo-toxicity (exposure to UV or blue light, oxidative stress, inflammation, poor diet low in B vitamins, Carotenoids, and high consumption of saturated and trans fats; all are important in progression and initiation of the AMD.

The evidence suggests that chronic vascular disease, including cardiovascular disease, as a potential cause. It is believed that slow degradation of the retina's blood vessels may lead to macular degeneration. Blockages and increased pressure of the blood vessels in the vascular layer of the eye (Choroid), possibly due to vascular disease, lead to increased ocular rigidity and less efficiency in retinal blood circulation. Cholesterol exists within the drusen spots. Research suggest that the AMD lesions and its symptoms are due to the accumulation of sub-endothelial apolipoprotein B, which is a similar condition to atherosclerotic coronary artery disease (Curcio 2010) Therefore the predictive bio-markers for cardiovascular risk such as elevated homocysteine, LDL, and C-reactive protein (CRP- Inflammatory marker) levels, are considered risk factors for AMD as well. Drusen accumulations continue to grow with advancing age; Those over 75 are 16 times more likely to develop large drusen compared to those 43-54.

Loss of elastin and collagen in Bruch’s membrane (the barrier between the retina and the choroids) and increased formation of the abnormal blood vessels which are also more fragile than typical blood vessels, cause blood and protein leakage below the macula.

Age-related accumulation of low-molecular-weight, photo-toxins, , metabolic by-products, and reduced enzymatic activity of the photoreceptor cells in the retinal pigment epithelium (RPE) is associated with drusen formation.

Oxidative stress is increased due to bad diet, exposure to UV, and smoking resulting in further inflammation in macula. The retina is susceptible to oxidative stress because of its high consumption of oxygen, high proportion of polyunsaturated fatty acids, and exposure to visible light have consistently shown to contribute to photochemical retinal injury.

Based on the genetic and epidemiology data, those who have a close relative with AMD have a 50% higher risk of eventually developing it compared to 12% for other people.

Natural Medicine For Prevention & Management of AMD

There is a well established the relation between the density of macular pigment (MP) and the onset of AMD. Macular pigments include family of main Carotenoids such as lutein, zeaxanthin, and meso-zeaxanthin(Meso-zeaxanthin is a synthetic form of natural zeaxanthin). These carotenoids are found within the macula, surrounding tissues and vessels. Lutein,& zeaxanthin participate in filtering out UV light and act as antioxidants .

Due to aging levels of these carotenoids decrease; and low levels of MPs are linked to AMD (Johnson 2010). Although there is a decline in all three types, meso-zeaxanthin found to have a sharp decrease in the macula of macular degeneration subjects. All three carotenoids are considered to be very important in maintaining the structural integrity of the macula.

Supplementing with lutein and zeaxanthin is an important preventative measure, but may also help reverse the degeneration process in the long term use. Lutein and zeaxanthin have the tissue-specific characteristic of all carotenoids, their natural tendency is to concentrate in the macula and retina. The denser the pigment, the less likely a retinal tear or degeneration to happen. Zeaxanthin is not easily found in the diet, but when taken as a supplement, it is absorbed into the blood stream and effectively increases macular pigment levels.

Powerful antioxidantsincluding Anthocyanidins and Cyanidin-3-Glucoside (C3G) are found in bilberry. Taking bilberry extract supplements have provided a significat improvement for macular degeneration as well as other eye conditions including diabetic retinopathy, retinitis pigmentosa, glaucoma, cataracts, and poor night vision.

The anthocyanidins in bilberry helps decrease vascular permeability by interacting with blood vessel collagen to slow down the enzymatic damage on the blood vessel wall. This may prevent the leakage from capillaries that is prevalent in wet AMD. Bilberry extract also provides antioxidant properties and adding vitamin E has provided greater benefits .

Anthocyanidins and Cyanidin-3-Glucoside (C3G) are highly bioavailable and enhances each other functions. They protect vessels endothelial cells against peroxynitrite (which cause endothelial dysfunction and vascular failure. They help lowering vascular inflammation while improve the activity of endothelial nitric oxide synthase (eNOS), which helps maintain normal vascular function. These benefits on blood vessels are important for retina's delicate circulation and nerve cells.

Grape Seed Extract is high in bioflavonoid with potent antioxidant properties. Bioflavonoids protect retinal ganglion cells and prevents aggregation of pathologic proteins, which suggests to provide protection against macular degeneration and neurodegenerative disorders. In vitro grape extracts can inhibit angiogenesis in human cells suggesting it may help suppress the abnormal blood vessel growth in wet AMD. In animals Grape seed extract helped reduce rate of ocular blood vessel damage seen in diabetic retinopathy.

Ginkgo Biloba in addition to provide antioxidant benefits, is well known to help improve microcapillary circulation. This property is also beneficial the eyes and slows deterioration of the macula. Ginkgo Biloba helps inhibit platelet aggregation , regulate blood vessel elasticity, and improve blood flow through major blood vessels and capillaries.

Quantities of Glutathione and Vitamin C are substantially decreased in the eyes of AMD patients . Combination of Glutathione and Vitamin C with cysteine (NAC) helps to improve Glutathione synthesis , due to the fact that cysteine remains stable in aqueous solutions and is a precursor to glutathione . Vitamin C absorbs UV radiation, which contributes to cataracts .

R- lipoic acid is considered a universal antioxidant because it is fat and water soluble. It improves the life cycle and activity of other antioxidants. In animals R- lipoic acid helped reduce new abnormal vascular formation in the eyes.

Selenium is an essential trace mineral. It is a co-factor for the activity of the antioxidant enzyme glutathione peroxidase. Selenium is important in slowing the progression of AMD and other eye disorders including cataracts and glaucoma .

L-Carnosine is a naturally occurring antioxidant and anti-glycation agent (glycation is a process through which excessive sugar bound to fat and protein molecules and form highly oxidative compounds). L-carnosine inhibits lipid peroxidation and free radical-induced cellular damage N-acetyl-carnosine helped prevent light-induced DNA damage, repaired damaged DNA strands , and improved visual acuity, glare and lens opacification in animals and humans with advanced cataracts.

A high concentration of Amino Acid Taurine is found in the retina. Taurine deficiency is contributes to alteration of retina's structure and function.

Coenzyme Q10 (CoQ10) may protect against free radical damage within the eye. Mitochondrial DNA (mtDNA) stability is necessary for proper function of mitochondria. In all regions of the eye, mtDNA damage is increased as a consequence of aging and age-related disease. Supplementing with combination of antioxidants including CoQ10, acetyl-L-carnitine, and omega-3 fatty acids helped improve the function of mitochondria in retinal pigment epithelium and subsequently stabilized visual functions in participants with early AMD.

Similar risk factors contribute to both AMD andcardiovascular disease (CVD), especially elevated Inflammatory biomarkers such as CRP and homocysteine. Elevated levels of homocysteine, is associated with low levels of certain B vitamins and increased risk of AMD and vision loss in older. Supplementing with folic acid, B6, and B12 can significantly reduce the risk of AMD in adults with cardiovascular risk factors. Taking daily B vitamin supplementation which included therapeutic dose in bio-available form of folic acid , B6, and B12 helped prevent and reduce risk of developing AMD in participants.

Vitamin B2 (Riboflavin) in B complex vitamin helps reduces oxidization of glutathione and prevent light sensitivity, reduced visual acuity, as well as burning and itching in the eyes.

Fruits with a yellow or orange color such as mangoes, kiwis, oranges, and vegetables of the dark green leafy, orange and yellow varieties are sources of lutein and zeaxanthin. Consuming such foods provide a direct effect on macular pigment density.

Food rich in Omega-3 fatty acids like oily arctic fish such as salmon, mackerel, Alaskan Pollock as well as plant/ algal sourced omega 3s are important for protection against macular degeneration and other diseases . Patients with a high dietary intake of omega-3 fatty acids had a 38% lower risk of late (more advanced) AMD.

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