How we see

I'm Paddy and I'm going to try and explain how you see things.

Seeing things (vision) is one of the most amazing things you can do. You may well think that you see with your eyes, and that’s true - you do. But that’s not the whole story, because you also see with your brain. Without your brain, you wouldn’t be able to see at all.

To see, you also need light. Light is reflected off objects and enters your eyes. The eyes then focus the light (a bit like a magnifying glass does) and turn it into a message that they send to the brain. So it is inside the brain that we actually see things.

The way we see things depends on where the reflected light is coming from. If it’s coming from exactly where you’re looking, you see things sharply and in detail; this is called our "central vision". If it’s coming from somewhere off-centre, it falls within our side vision, or "peripheral vision".

Both central vision and side vision are important. Without central vision, we couldn’t read, recognise faces or look at things directly. Without side vision, it would be very difficult to move around without bumping into things!

If you only have one eye, it can be hard to judge distances, or depth. With two eyes, what you see appears in three dimensions (3D) and you can tell roughly how far away things are. To test this, try catching a ball with one eye closed. You can probably still do it, but it’s quite a bit trickier!

Find out exactly how the eye works.