By Dr Mercola
The human retina is about the size of a postage stamp andthe macula only about the size of a pencil tip. Yet hundreds of millions of light-receptor cellsare employed. Cone cells produce color vision and are located in the macula.Rod cells produce black and white for night vision. The cone cells arelocated in the center of the retina and are used for reading and finecentral vision. The rods are in the periphery of the retina and are usedfor night and side vision. Degeneration of the rods results in night blindness(retinitis pigmentosa). Degeneration of the cones results in macular degeneration.
From back to front, the maculais nourished by the choroid or blood layer of the retina. Poor circulationwould then affect vision. The choroid has extensions into the retina.If the capillaries (connectors) become leaky, then the chorio-capillaruswill ooze some blood serum behind the retina, called subretinal swelling.If the capillaries become even more leaky, then red blood cells will oozebehind the retina and become a sub-retinal hemorrhage.
VitaminC and bioflavonoids (bilberry, cranberry, blueberry, others) help to keep strong capillaries.
Furthermore, the back of theretina is protected from sunlight damage by brown melanin pigment. Asmelanin pigment dissipates with age, macular degeneration accelerates.Plant pigments like bilberry mimic the light-absorption of melanin.
The blood and its nutrients(oxygen, vitamins, lutein) must pass a membrane, called Bruch’s membrane,which may become calcified over time, blocking nutrient entry and theexit of cellular debris. This can be remedied by taking magnesium, a calcium-antogonist(natural calcium blocker).
Once nutrients have passedBruch’s membrane, they go thru a single-cell layer of cells called theretinal pigment epithelium (RPE). The RPE are garbage-cleaning cells.They digest used-up portions of vitamin A shed from the rod cells everymorning. The RPE accomplishes this by producing an antioxidant calledglutathione peroxidase, which is generated from vitamin E and selenium.
Without Vitamin E and selenium, the RPE will build up cellular garbage deposits.
If nutrients pass through thechoroid, Bruch’s membrane, and the RPE, then they finally reach the retinallight-receptor cells, the rod and cones. These cells are lined with fat– – omega-3 fat called DHA. Studies show that people who consume morefish, which is rich in DHA-fish fat, are less likely to develop maculardegeneration. Vitamin B12 is the glue that keeps the DHA in place. VitaminE protects the DHA-fat from turning rancid.
In front of the photoreceptorsis the nerve layer of the retina. These nerve cells transmit visual signalsvia the optic nerve to the brain. It is in this nerve layer thay luteinand zeaxanthin reside. These are two yellow dietary pigments that worklike sunglass filters to protect the underlying macula from solar radiation.Blue-eyed adults have far less lutein and zeaxanthin in their retinas.
A recent study shows that 60-yearolds who had adequate retinal levels of lutein and zeaxanthin retainedthe ability to see faint light as well as 20-year old adults!! How’s thatfor anti-aging. Lutein and zeaxanthin are acquired from spinachand kale, and from food supplements as extracts of marigoldflower petals. At least 6 milligramsof lutein and zeaxanthin should be consumed daily. (Centrum multivitaminonly provide 1/4th of one milligram!.)
A nutritional regimen for macular degeneration should include:
1. Habitual wearing of UV-blueblocking sunglasses when outdoors in daylight.
2. Consumption of spinach andkale
3. A daily food supplementregimen that include lutein (6-12 mg), vitamin E (200-400 IU), selenium (organic, nor selenate or selenite) 200 mcg; vitamin B12, 300 mcg; magnesium 400 mg; vitamin C 500-2000 mg; bilberry 120-240 mg; DHA-rich fish oil providing 1000 mg of DHA; sulfur-bearing nutrients (glutathione, lipoicacid, N-acetyl cysteine or taurine).
4. Avoid high-dose calcium supplements without balancing magnesium (60:40 ratio).
5. Avoid hydrogenated fats that interfere with the omega-3 fats.
6. Avoid very low-fat diets, that rob the retina of omega-3 fats.
7. Eat sulfur-rich foods, such as garlic, eggs, asparagus, onions.