CHANCES are you only really focus on your eyes when there’s something wrong – think nasty infection or an eye sight check.
But your peepers can tell you a lot about your wider health, sometimes tipping you off to conditions like diabetes and high cholesterol.
Our series focusing on the weird and wonderful facts about various parts of the body has seen bizarre revealations about your breasts, bums, mouths, vaginas and penises.
Next up it’s eyes – they might not seem as fascinating on the face of it, but there’s a lot about this organ that might surprise you.
From whether you actually stop ‘seeing’ when you close your eyes to sleep, to how many times you blink a year and how all eyes are actually brown – here are 10 fantastic facts about your peepers.
Ever wondered what the hazy red glow you see when you close your eyes is?
That’s the inside of your eyelids! Your eyes don’t stop seeing when you close your eyes and your eyelids still let some light through.
Try closing your eyes in a lit room and then hold your hand in front of your closed eyes, you will be able to see that it has got slightly darker.
Even in the dark, you still see some kind of flashing light or moving stars when you close your eyes.
Your eyes even continue to ‘see’ and send visual information to your brain while you are sleeping. That is why as it gets lighter earlier in the summer you are more likely to wake up early.
Vision is not just about the light that you see.
Your peepers also respond to stimuli. For example, even with your eyes shut, lights and colours may appear when you sneeze or cough, or even if you gently touch your eyelids when your eyes are shut.
It is not quite as simple as you might have been taught, there are many more colours of eyes than brown, blue and green.
In fact every iris, the coloured part of your eye, is unique though there are six main shades – brown, blue, green, grey, amber and hazel.
In albinism, a health condition in which there is less melanin, which gives skin, eyes and hair their colour, the eyes can be various colours, most commonly blue but including pink. Your iris is unique to you, and is a way of identification, rather like your fingerprints.
This sounds contradictory, but they are, even though we see different colours when we look at people’s eyes.
This is because they have a different amount of melanin in the eye.
Melanin is brown, and the more melanin you have in your iris the more light is absorbed, meaning they look browner.
But if you have less melanin in your iris, it means that more light can be reflected back out, reflecting at shorter wavelengths which look blue.
Add to this, some eyes appear to change colour, depending on the light, due to what is reflected back.
This is also why babies seem to be born with blue eyes, because they are still developing melanin in the iris.
Each blink is approximately one tenth of a second.
Despite this you can’t actually blink 10 blinks in a second, maximum tends to be about five blinks a second even if you are really fluttering those peepers!
Most people tend to blink every three or four seconds, or about 15 to twenty times per minute, around 5 million times a year.
If you find yourself in a staring competition and your eyes start smarting, the uncomfortable sensation is due to the tear film drying out over your eyes.
So tip your head back and your chin up so you are ‘staring’ at your competitor out of the smallest gap in your eyelids.
Also if you are in a staring competition with a child they may well beat you, as the tear film of young children is more stable than adults, especially if you have dry eyes, meaning that you are likely to need to blink first!
And not just from all that blinking!
There are lots of muscles in the eyes but the sensation of heavy, tired eyes may not be from the eye muscles themselves.
It may be related to a headache, or from a fever, or even from dry eyes.
Looking at a computer screen constantly can dry your eyes out, and even continually focusing on small text when reading can lead to eye tiredness.
Try to stick to the 20-20-20 rule: if you spend a lot of time at a computer, every 20 minutes look up and focus 20 metres away for 20 seconds.
Your eyes send visual information down the optic nerve to your brain, and they send a lot of it from the light which you see.
But it is the visual cortex in your brain which processes that information into an image.
The way that the eye works means that any light is upside down, so if your eye ‘sees’ upside down, it is your brain which translates the image the correct way up.
Every time you blink you replenish the tear film over your eyes to stop them drying out.
You cry to keep your eyes clean, and actually if you have dry eyes your eyes might water to try and compensate.
But it isn’t known why we produce tears when we are upset, or for other emotions such as fear, anger or happiness.
It may have developed as a social cue, to help others understand what we are feeling but not everyone cries in relation to their emotions.
As for babies, they cry for various reasons, because they are hungry, or wet, or cold, or tired, or want a cuddle, they cry to tell their carers something.
But that crying, at least initially, is a sound and does not involve tears – these tend to appear from about a month old.
The retina at the back of the eye contains on average 120 million rods, which are sensitive to light and 6 million cones which are involved in seeing colour.
The optic nerve connects your brain to the back of the eye and the spot at which it connects to the retina is actually your blind spot, meaning that essentially there is a hole in your vision, an area you cannot see.
But we have binocular vision, one eye fills in the gaps of the other.
This is not the same as the blind spot when driving, that is the area of the road which can’t be seen by looking in either in the rear view or side mirrors, so always check over your shoulder!
Scientists have long thought that newborns are colourblind and only see in shades of black, white and grey but newer research suggests that they can see some limited colour.
Their vision is not fully developed, in fact newborn babies can only focus on objects at about 30cm away from their face.
It is thought that red is the first colour which babies can distinguish clearly and that they can see red, yellow and blue by about two months of age.
Colour vision is thought to continue to develop until about four or five months old.
Not enough eye contact can feel socially awkward, as can too much!
There have even been studies carried out on what the perfect amount of eye contact is when you first meet someone,to strike the balance between connection and making someone uncomfortable.
Apparently the magic number is about four seconds!
Added to this your pupils dilate, not just in response to being in a dark room when compared to a bright one, but also if you are attracted to someone.
In fact as far back as Roman times, the belladonna plant – belladonna meaning beautiful woman – was used by women to dilate their pupils.
But please don’t do this!
The saying is that your eyes are the windows to your soul but it may actually be that your eyes are the window to the rest of your health.
There can be changes in the back of the eyes related to health conditions such as diabetes and high blood pressure. Be sure to get your eyes tested regularly.
THERE a plenty of things you can do to keep your peepers healthy, from eating well to getting them checked regularly.
Source: Moorfields Eye Hospital
