The eye’s squishy, stretchy lens is surrounded by muscles called ciliary muscles which contract to change the lens between fat and thin.

The lens’ thickness changes when you look at things that are close or far away so that the image is projected perfectly onto the retina.

If these muscles can’t change the shape of the lens quite enough, things might look blurry, and that’s why people wear glasses or contact lenses – to give the eye’s own lens a bit of help!

There’s a few different conditions that affect the eyes and cause people to wear glasses:

Presbyopia

Presbyopia is all to do with the way that getting older affects our eyes.

Even if someone’s had perfect vision all their life, as they get older, they might find that it gets harder to see things close up like the words in a book or stitches in some sewing.

They might find that they have to hold things further away to see clearly and sometimes people might say that their arms just aren’t long enough! It’s thought that over time the lens and muscles in the eye become less elastic and lose power, meaning the lens can’t focus in the way it should.

But don’t worry, it’s often possible to solve the problem with glasses or contact lenses, or even simple things like using magnifying glasses!

Astigmatism

Astigmatism is a common and usually minor condition of the eye that makes things look blurry or distorted.

It happens when the cornea or lens at the front of the eye is not a perfectly curved shape. The cornea should be shaped like a football, but in cases of astigmatism, it has an irregular curve, more like a rugby ball.

This means that light rays entering the eye are not focused properly, which is what makes things look blurred.   Most people who wear glasses have astigmatism and glasses help the eye focus correctly.

If left untreated, astigmatism can cause headaches, eye strain and fatigue.  So it’s important to make sure that you have the right glasses and regular eye tests to keep an eye on things!

Myopia

People who are myopic are sometimes called “short sighted”. Myopia is basically an issue that some eyes have in focusing on things at a distance.

It happens when the cornea, which is part of the eye, or the eyeball itself is a little more elongated than normal.  This means that light entering the eye focuses on a point within the eye rather than on the retina that’s the part of the eye that carries the signals to your brain.

This causes the eye and brain to see the image of a distant object as a blurred image.

People with myopia often squint while watching television or when trying to see distant objects.  Being short sighted is very common and often occurs with many members of the same family.

It can be helped by wearing glasses or contact lenses which help the light to focus on the right part of your eye to make things look much clearer!

Hypermetropia

More usually, people with this eye condition are called “long sighted”.  It’s a very common condition and affects the way your eyes focus on things.

It makes it difficult to see things which are close, but often the person can clearly see things which are far, far away!

Hypermetropia happens when the cornea or parts of the eye, are a little flatter than normal.  This means that light entering the eye focuses on a point behind the retina – that’s the part of the eye that carries the signals to your brain.

This causes the eye and brain to see things which are close as blurred images.  Both long sighted and short sighted are very common conditions and often will affect many members of the same family.

But don’t worry – wearing glasses or contact lenses helps the light to focus on the right part of your eyes and make things look much clearer!

Next: What happens at the opticians?

> Visit Professor Hallux’s i-Guide homepage
> Download the free i-Guide podcast from iTunes