5 fascinating facts about vision

Wednesday, 11 October 2017 by Callan Smith-Sheerin

World Sight Day is a great opportunity to focus attention on the issues surrounding blindness and vision impairment. Regular eye tests are the most effective way of detecting anything that might be wrong with your vision or eye health, so it’s important to get a check-up at least once every two years.


This year, our parent company Essilor have started the #putvisionfirst initiative, donating to charity for every person that pledges to get their eyes tested.

We all know the importance of vision in daily life, but did you know that some people see bright spectrums of colour instead of the colour grey? Or that it’s just as important as taste in deciding whether your dinner is delicious? We’ve pulled together 5 of our favourite fascinating facts about vision for your enjoyment this World Sight Day.

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Your sight can compensate for a lack of taste

…and we don’t mean in the case of your fashion sense. Sight is almost as important as taste when it comes to enjoying your food. Looking at an orange gives us the clearest indication that what we’re eating is an orange. If you, for some reason, had a cold and were also blindfolded while you ate a slice you might not be as confident that you were eating an orange.

What we call ‘taste’ is a fusion of smell, touch, sight and flavour. As there are only five pure flavours; sweet, sour, bitter, umami and salty, these other senses come into play when we talk about the smaller or more subtle differences.

Your eyesight is so crucial to the perception of flavour that even culinary experts have been fooled. One test involved dying white wine red and serving it to a group of connoisseurs. Despite their years of experience and training, when they were asked to describe the wine, they used characteristics of red wine rather than white. This suggests that merely changing the colour of the drink completely altered what they thought of it.

We've all got our blind spots

It’s a quirk of the eye’s design that all of us have an area that we can’t see out of. Vision works by light passing through the pupil and being bent (or refracted) by the cornea, so that it hits the retina that covers the back of the eye. The retina then passes the information to the optic nerve which carries it to the brain to process it into an image.

As a physical part of your eye, the optic nerve is limited by its size and shape. There is a section of your retina that it can't receive information from, leaving you with a blind spot in each eye. Having two fully functioning eyes means that one picks up the other’s blind spot but, if you're curious, there’s a quick and fun way to find yours for each eye.

First, draw two dots next to each other with a gap between them on a plain piece of paper. Cover one eye and hold the paper with your free hand, holding it straight in front of you so the two dots are the same distance from the ground. Focus on one dot and bring the paper closer and further away from your face. At one point, the other dot will disappear and, voila!, you’ve found your blind spot.

It may seem like poor design for us to have blind spots in our anatomy, but it’s fairly common across the animal kingdom. Credit has to go the squids and octopuses of the world, who have managed to get it right, with totally perfect vision. Well done guys!

Meet the women who see rainbows

rainbow-in-grey-cityMost humans have something called trichromatic colour vision. This means that we have 3 types of ‘cone’ cells that are responsible for helping us recognise colour. However, there is a small proportion of people with tetrachromatic vision, which means they have 4 of these cones of vision. This gives the individual the potential of seeing even more colours as well as combinations that most cannot see. An unusual aspect of this condition is that only women experience it, due to the fact that you need two X chromosomes to have this condition.

An even smaller segment of these people report that when they look at something such as a plain grey pavement, they see something very different to most other people. Instead of the drab grey that we’re all used to, a tetrachromat can see a myriad of pinks, oranges, blues and more, spilling out like a rainbow. It’s an incredible thought and if you want to see how the world looks (well, as much as possible) with tetrachromia, check out the art of Concetta Antico, who has the condition and attempts to convey what she sees through her paintings.

How did you end up getting stars in your eyes?

When we’re sleepy a normal reaction is to rub our eyes in an attempt to refresh them. Afterwards, you’ve probably noticed specks of coloured light in a variety of different shapes. These can be spots, stars and so on.

This phenomenon is caused by pressure on, or stimulation of the retina at the back of your eye. To keep it perfectly round, your eye is filled with a thick fluid which, when you rub your eyes, presses against the retina. As the retina is responsible for sending information to the brain via the optic nerve, the pressure distorts this information and ends up confusing the brain, causing the blemishes on the image we see.

You might have noticed the same thing after sneezing or standing up too fast. Sneezing causes a sudden jolt which shakes the retina, while standing up too fast means that the blood flow which carries oxygen around the body is slower than it should be. This means the retina is starved of oxygen and can’t function as they normally does.

Nothing we see looks exactly as we think it does

bowl-of-fruitWe’re getting a bit deeper with this one! The image we see of the world around us we know is completely unique to each person, and is affected by a range of different factors.

Take a colourful bowl of fruit as an example. During the day it will seem to be bursting with bright and vivid colours, but this is a result of our eyes and brain working together. It’s the eyes’ job to absorb light, process the information and deliver it to the brain where this information is then interpreted into the image we see.

If you change something about your environment, the image you see will be different. Looking at that same bowl of fruit in the dark, you don’t see the same colours, nor would you if you were colour blind. If you stare at the fruit bowl with one eye closed, it will appear to be in a different position or have different proportions.

So, can we ever know what something truly looks like? Probably not. Is the ‘red’ apple at the top of this bowl still red at night? Well, as the colour red is a property of visible light which you cannot see in total darkness, it’s difficult to say. If that’s the case, can it ever really be called red? At Vision Direct, we like to ask the big questions!

We don’t know about you, but these facts only help to make us even more fascinated about our vision and goes to show how complex it is. Remember, particularly this World Sight Day, just how important and amazing your eyesight is and commit to getting an eye test at putvisionfirst.com

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