BOSTON - Engineers at the Massachusetts Institute of Technology (MIT) have designed a retinal implant for people who have lost their vision.
The retinal prosthesis may help restore some vision by electrically stimulating nerve cells that normally carry visual input from the retina to the brain.
The chip will not restore normal vision but can help blind people navigate a room or walk down a sidewalk more easily, say MIT researchers.
“Anything that could help them see a little better and let them identify objects and move around a room would be an enormous help,” says Shawn Kelly, a researcher at MIT.
Patients who receive the implant would wear a pair of glasses with a camera that sends images to a micro-chip attached to the eyeball.
The glasses also contain a coil that wirelessly transmits power to receiving coils surrounding the eyeball. When the micro-chip receives visual information, it activates electrodes that stimulates nerve cells in the areas of the retina corresponding to the features of the visual scene.
The electrodes directly activate optical nerves that carry signals to the brain, bypassing the damaged layers of retina.
The research team, led by John Wyatt, MIT professor of electrical engineering and computer science, recently reported a new prototype that they hope to start testing in blind patients within the next three years, after some safety refinements are made.
These findings are slated for publication in IEEE Transactions on Biomedical Engineering.
Potassium is a mineral that is involved in both electrical and cellular functions in the body. (In the body it is classified as an electrolyte).
Potassium is a very important mineral to the human body. It has various roles in metabolism and body functions:
* It assists in the regulation of the acid-base balance and water balance in the blood and the body tissues.
* It assists in protein synthesis from amino acids and in carbohydrate metabolism.
* It is necessary for the building of muscle and for normal body growth.
* It is needed for the proper functioning of nerve cells, in the brain and throughout the body.
Potassium in Diet: Food Sources
Fish such as salmon, cod, flounder, and sardines are good sources of potassium. Various other meats also contain potassium.
Vegetables including broccoli, peas, lima beans, tomatoes, potatoes (especially their skins), and leafy green vegetables such as spinach, lettuce, and parsley contain potassium.
Fruits that contain significant sources of potassium are citrus fruits, apples, bananas, and apricots. Dried apricots contain more potassium than fresh apricots.
Potassium in Diet: Recommendations
There is no recommended daily allowance for potassium, although experts recommend approximately 2 to 2.5 grams per day. The average American diet provides 2 to 6 grams of potassium per day.
Over-the-counter potassium supplements provide 99 milligrams of potassium per tablet. Potassium supplementation should never be taken without the approval of your GE E-Care health care provider.
Potassium in Diet: Side Effects
A deficiency of potassium (hypokalemia) can occur in people with chronic disease or as a result of the aging process. The most common problems associated with reduced potassium levels are hypertension, congestive heart failure, cardiac arrhythmias, depression, and fatigue. A variety of conditions can cause the loss of potassium from the body. The most common of these conditions are vomiting, diarrhea, and other gastrointestinal problems.
Hypokalemia can also be caused when too much water is taken in too quickly in conjunction with heavy perspiration — for example, in an overzealous attempt to prevent dehydration during sports. This can affect marathon runners and other serious athletes.
Renal disease (such as acute renal failure) and diabetes, depending on the stage of either, can also cause fluctuations in the levels of potassium. Additionally, many medications can cause depletion of potassium. Examples include diuretics, cortisone, prolonged use of aspirin, and laxatives.
The most common symptom of potassium depletion is fatigue. Other symptoms of potassium deficiency include slow reflexes, muscle weakness, and dry skin. A quick loss of potassium could lead to cardiac arrhythmias.
Severe potassium deficiency symptoms include decreased heart rate, extreme muscle weakness, bone fragility and, if untreated, death. A low level of potassium can be determined with a blood test and can be treated with potassium supplements.
Increased levels of potassium in the blood is known as hyperkalemia. Some common causes of this are reduced renal (kidney) function, an abnormal breakdown of protein, and severe infection. If there is no pathological cause for increased potassium levels, the kidneys are able to handle a large amount of potassium, and prevent the blood levels from increasing.
Why Frequent Blinking is Essential for Healthy Eyes and Optimal Vision
Are you interested in taking optimal care of your eyes and experiencing your best vision? If so, we encourage you to get into a habit of blinking softly as often as possible.
Frequent and gentle blinking is essential to the health of your eyes and vision because it allows your eyelids to regularly coat your eyes with three beneficial layers of tears:
The first layer of tears lies right up against the whites of your eyes, and provides an even coat of protein-rich moisture for the second layer to adhere to.
The middle watery layer helps to wash away foreign debris. It also nourishes the cornea of your eyes with minerals, a variety of proteins, and moisture.
The third outer layer of tears is somewhat oily. It serves to prevent the middle watery layer from evaporating quickly, and provides needed lubrication between your eyes and your eyelids.
If your eyes are not regularly coated with the three layers of tears described above, they will be deprived of ongoing nourishment and cleansing, and they will be unnecessarily strained.
One of the reasons why many of us don’t blink as often as we should is that we don’t see frequent blinking in mainstream media. Actors and anchor-people are typically trained to blink as infrequently as possible, so when we take in mainstream media, our subconscious minds learn that it isn’t normal to blink frequently.
To optimally support your eyes and vision, it’s best to blink softly every two to four seconds, which translates to about fifteen to thirty blinks per minute. By consciously making an effort to softly blink at this rate, over time, your body will turn your conscious efforts into a subconscious habit.
Here are some notes on blinking to promote optimal eye health and vision:
A soft and natural blink should occur like the light flap of the wings of a butterfly - this is a good image to visualize as you make an effort to blink softly every two to four seconds.
You should blink regularly during all activities, including reading, working on the computer, and viewing a TV program or film.
Contact lenses can discourage frequent blinking because the back surface of your eyelids is not designed to rub over an artificial surface. This is one of several good reasons why contact lenses should be avoided whenever possible.
Some yoga and meditation instructors suggest doing exercises that involve fixating your vision on one object, such as the flame of a candle, and doing your best not to blink. We encourage you to ignore the part about suppressing your instinct to blink. It’s quite possible to experience inner stillness and peace while blinking frequently.
Since the primary goal of blinking regularly is to keep your eyes well lubricated and nourished, another good tip for eye and vision care is to keep your eyes closed whenever you are thinking about something while you do not need your vision. For example, if you are stuck in the middle of composing an e-mail message, close your eyes while you think of your next sentence.
Many plant-based eaters are under the impression that they can obtain all the vitamin A that they need from plant foods that contain carotenoids, particularly beta carotene found in foods like spinach, sweet potatoes, and carrots.
It’s true that some carotenoids like beta carotene can be converted to vitamin A in your body once they make it into your blood. What you may not know is that carotenoids are not always absorbed efficiently into your blood.
Given that vitamin A deficiency is one of the most common nutritional deficiencies in the world and is also a leading cause of death in young children, it’s critical for the general public to know that relying solely on carotenoids in plant foods for daily vitamin A needs may lead to any of the following health problems over time:
Skin Lesions Like Acne and Acne Rosacea: Vitamin A is needed to develop and maintain moist and healthy epithelial tissues, including your skin. Many long time vegans find it difficult to understand why they have acne while on a whole food, plant-based diet. Vitamin A deficiency is undoubtedly a common cause of acne for all acne sufferers, but particularly for people who eat mainly a plant-based diet and don’t include a reliable source of vitamin A in their diets.
Poor Night Vision: Vitamin A combines with a protein in the back of your eye to enable night vision.
Weak Bones, Weak Teeth, and Poorly Spaced Teeth: Vitamin A is needed for proper growth and maintenance of bones and other soft tissues throughout your body.
A Weak Immune System: Because vitamin A is needed for the development and maintainance of all of your body’s barriers to infection like your skin, lungs, and the mucosal linings in your digestive and urinary tracts, a deficiency almost assures you of an immune system that is not as strong as it can be.
Cancer: Since vitamin A is essential to the health of your immune system, a deficiency could increase your risk for developing certain forms of cancer, such as breast, lung, stomach, and cervical cancer.
Anemia and Associated Fatigue: Vitamin A is needed for proper red blood cell formation.
Vitamin A is actually a group of compounds that includes retinol, retinal, and the carotenoids. Retinol and retinal are found in animal foods such as liver, eggs, and butter. Because these forms of vitamin A are ready to be used by your body straight from their food sources, they are often referred to as pre-formed vitamin A.
Carotenoids, in turn, are often referred to as provitamin A since they are precursors to Vitamin A and need to be converted in your body.
The total vitamin A in your diet is therefore a combination of the pre-formed vitamin A and provitamin A in your diet.
It’s important to note that optimal absorption of retinol, retinal, and the carotenoids into your blood requires an adequate amount of healthy fat in your diet. This is because pre-formed and provitamin A are fat soluble compounds that are best absorbed into your blood in the presence of digestive juices that are needed to digest fat. The more healthy fat you include in your diet, the better you will absorb fat-soluble vitamins A, D, E, and K into your blood.
It is not practical to offer a chart that lists specific amounts of useable vitamin A in different foods because the amount of vitamin A that ultimately reaches your blood depends on the variables described above.
So, here are two simple lists of healthy foods that contain significant amounts of pre-formed and provitamin A. I believe that it is best for most people to eat foods from both groups on a regular basis to to meet their daily vitamin A needs.
Pre-formed Vitamin A:
Organic beef liver
Organic lamb liver
Organic eggs
Organic butter
Cod liver oil
Provitamin A:
Sweet potatoes or yams
Cantaloupe
Spinach
Carrots
Butter nut squash
What About Toxicity?
With the exception of cod liver oil, all of the other foods listed above have virtually no potential to cause vitamin A toxicity in your tissues. So long as you stick to an appropriate dose of cod liver oil, you can rest assured knowing that you aren’t getting too much vitamin A each day.
Every study that discusses the potential for vitamin A toxicity looked at synthetic sources of vitamin A. Clearly, it is best to get vitamin A from the healthy foods listed above and to avoid synthetic sources at all times.
‘Bionic Eye’ May Help Blind See: Retinal Prosthesis Shown To Restore Partial Vision
ScienceDaily (Oct. 21, 2009) — A new artificial retina, an array of electrodes implanted on the back of the eye, has been found to restore partial vision to totally blind people. In a study focused on 15 blind participants who had the implant for at least three months, 10 of the patients subsequently tested were able to identify the direction of moving objects.
The research was presented at Neuroscience 2009, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.
“These results give new hope to the many people with degenerative retinal diseases,” said Jessy Dorn, PhD, of Second Sight Medical Products, Inc., lead author of the study. More than two million Americans suffer from eye diseases such as retinitis pigmentosa and age-related macular degeneration, slowly losing their vision as the nerve cells that detect light are destroyed, due to either age or illness. There is no known cure.
In this case, the researchers worked around the destroyed cells. Each participant was given a pair of glasses with a small video camera mounted on it, and a belt with a tiny computer attached. The computer processed video images from the camera and transmitted the data to the implanted electrodes on the retina. When the users “looked” at a monitor with a white bar sweeping across a black screen, the electrodes that corresponded with the moving bar stimulated cells in the eye, creating spots of light in their fields of vision.
“We found that most of the study participants were better able to determine the direction of the bar when using the prosthesis system than without it, or with a scrambled video input,” Dorn said. “In other words, this new system gave most blind people the ability to identify an object’s direction of motion — something they could not do without it.” An international clinical trial is now testing the prosthesis system. To date, 32 blind people have received the implant.
Research was supported by the National Eye Institute.
