Practice your "inner bat" (18)

This is amazing, and its good to know that there is still hope should we ever lose our eyesight...
http://www.bbc.co.uk/news/health-22805748

Use your 'inner bat' to navigate

Bats are known for using sound to navigate successfully, and new research suggests we could all use our 'inner bat' to get around.

BBC.CO.UK

Will eating carrots help me to see in the dark ? The myth: Yes The truth: NO (17)

If you eat more carrots, it will NOT improve your vision in any way; despite the abundant myths, this is a fact.

Why do people say it will ? Because carrots contain vitamin A, and because vitamin A is required for vision, people quite reasonably conclude that eating carrots means better vision. But this is one of the long-standing myths that needs de-bunking. So here goes:

The retina is the light-sensitive layer (in the back of the eye) that detects the light and sends the image back to the brain so you can "see". Detection of the image requires production of pigments within the retina, which are made from Retinol (Vitamin A). Vitamin A is made in your liver from Beta carotene which is found in vegetables, especially kale, cabbage, broccoli, spinach, sweet potatoes, carrots. Vitamin A is also of course available already formed in animal products especially, of course, the liver (see above); and it is one of the fat-soluble vitamins so it is also found in oily fish, whole milk, butter and cheese.

But vision requires only a small amount of Vitamin A each day, and our livers store vast amounts of the stuff - so unless you have a very deficient diet for years, such as is very occasionally seen in severe alcoholics, you will have plenty of Vitamin A on board with no risk of Vitamin A related vision deficit. Extra vitamin A in the diet is no advantage to vision.

That said, beta carotene is one of the anti-oxidant substances that protect all of our body cells against the oxidative stresses of daily life. So it's a good addition to our diet for general health reasons.

In developing countries the situation is very different - prolonged nutritionally deficient diets there cause many health problems which, for Vitamin A deficiency include:
Impaired vision in dim light (= "night-blindness")
Dry eyes; can be so severe that the cornea (the clear window on the front of the eye) becomes opaque
Increased susceptibility to skin damage from sun
In children: reduced growth, restricted bone development
Increased susceptibility to infection

In developing countries, a carrot a day would be a fantastic improvement to their diet.
In developed countries, a carrot a day would be general good dietary advice, but not for reason of vision.

Too many carrots (more than about one large carrot per day) causes carotenaemia - not a big health risk, but it makes your skin yellow !

If you want to get accurate, regularly updated, evidence-based information from the people who treat patients with eye problems on a daily basis, this is the blog to visit again and again. (16)

What is this disease called AMD ? (12)

Age-related macular degeneration (AMD) damages the central part of the retina, known as the macula. Here's a cross-section of the eye (the eye cut through from front to back):

Viewed through the front of the eye, the normal macula looks like this:

 The most common form of AMD is called "dry" AMD, It simply consists of tiny pale yellow spots in the macular area, and it looks like this:

The "dry" situation can persist, usually gradually worsening, over many many years; during this time the person may see normally or may notice a very gradual reduction in their central vision (the part needed for detailed activities such as reading, or recognising faces). But in a minority of cases it can quite suddenly convert to "wet" AMD, where blood vessels grow under the macular area, which looks like this:

 In this wet situation, the person usually notices sudden onset of distortion in their central vision, followed after some hours/days by complete loss of central vision - so suddenly they can't see to read or recognise faces. Because the wet form is heralded by distortion in the vision, people with dry AMD are often warned to come back to their eye doctor within 24 hours if they notice any  distorted vision, for example kinks in their view of door frames/window frames etc.

So the above illustrates that in both dry and wet forms of the disease, you lose your central vision, the bit you need for accurate detailed seeing; in the dry form it happens over many years, whereas in the wet form it happens over hours/days.

Concise introduction to the eye and its more common problems. (10)

Have a look at this really good simple introduction to the eye and its more common problems:


CLICK HERE