An expert guide to common refractive errors

As we reach midlife, many things about our bodies begin to change, not least our eyes. If you’ve noticed that you have to hold your phone at arm’s length or closer to your eyes in order to read a text, or you’re struggling to read instructions on food packaging, you could be suffering from a common refractive error.

While myopia, hyperopia and presbyopia may sound like Latin plant names or mythical creatures from a children’s book, they are in fact the scientific names for some of the most common eye conditions, such as short-sightedness, long-sightedness and astigmatism.

Collectively these conditions are known as ‘refractive errors’ as they affect the way in which light travels through the eye and therefore the clarity with which we can see objects both near and far. They are also extremely common. In fact, short-sightedness is thought to affect up to one in three people in the UK – and it’s becoming more common.

So, what are the possible causes and treatments for these conditions, and what can we do to make sure our vision is as good as it can be?

Mr Alex Shortt, consultant ophthalmic surgeon at Optegra Eye Hospital London

Hyperopia

Otherwise known as long-sightedness or far-sightedness, hyperopia causes objects to appear blurred because the eye does not focus light on the retina, the light-sensitive layer at the back of the eye.

Most people with hyperopia have problems focusing on close objects, but some will have problems with distance and close objects at the same time.

A person may be long-sighted because:

— The eyeball is too short

— The cornea (transparent layer at the front of the eye) is too flat

— The lens inside the eye is unable to focus properly

It’s not clear what causes these problems but they’re rarely a sign of any underlying condition. Sometimes, long-sightedness may be a result of the genes you inherited from your parents or a result of the lenses in your eyes becoming stiffer and therefore less able to focus as you get older.

Myopia

Myopia, otherwise known as short-sightedness, causes objects in the distance to appear blurred while close objects are often seen clearly.

It occurs when the eye has too much focusing power, either because it’s too long or the cornea is more curved than usual, making the eye too strong. This means that the light doesn’t focus on the retina at the back of the eye properly but focuses just in front of the retina, making distant objects appear blurred.

There are some factors that can increase your chances of becoming short-sighted:

— Genes. You’re more likely to be short-sighted if one or both of your parents are too. Research has so far identified more than 40 genes linked to the condition, which are responsible for the eye’s structure and development and the signalling between the brain and the eyes.

— Too little time outdoors. Spending time outside as a child may reduce our chances of becoming short-sighted and existing conditions may progress less quickly. It’s a good idea to encourage your child to play outside to help reduce their risk

— Excessive close work. Spending time focusing your eyes on nearby objects, such as reading, writing and possibly phones and tablets, can also increase your risk of becoming short-sighted. Everything in moderation!

Astigmatism

If your cornea or lens develops into an irregular shape you will experience a condition called astigmatism. This usually happens alongside myopia or hyperopia.

The cornea should have a regular curve, a bit like the shape of a football, but for people with astigmatism, the cornea’s curve is more like a rugby ball. This means the cornea can’t focus light rays properly and can cause blurry vision.

Presbyopia

This condition is a result of natural ageing of the eye, which happens to most people in their forties, where you experience a loss of focus for objects close by, as the lens inside the eye becomes less flexible with time.

Presbyopia may occur in a person with good distance vision or with any of the other refractive errors (astigmatism, myopia and hyperopia). It is often incorrectly referred to as long-sightedness.

Treatments for refractive errors

Depending on the seriousness of the problem, contact lenses or glasses can be worn, but some people may find it less of a hassle to have one of the laser eye surgeries we offer at Optegra Eye Hospital London.

Laser eye surgery is ideal for those who are affected by short sighted, long sighted or astigmatism, where the shape of the eye affects focusing power.

For those with myopia (short-sight) who are not suitable for laser eye surgery, perhaps because their prescription is too strong, an alternative is to place a soft contact lens within your eye – either between your natural lens and the iris, or between iris and cornea. Known as refractive lens exchange, this is a particularly good alternative for those under the age of 40 because the natural lens of the eye, and its capacity for close-up vision, are retained.

Presbyopia can often be treated simply by using reading glasses for close, focused work. Alternatively, Presbyond is a type of laser eye surgery for people with presbyopia that blends vision for distance and near between the dominant and non-dominant eye, reducing or eliminating the need for glasses.

Clare O’Donnell, head of Optegra Eye Sciences, recently had this treatment. She says: “This is a solution for people like me who need different strength glasses for far and near viewing. The big advantage is the improved range of clear vision it provides. I do a lot of computer work, as well as reading, ‘virtual’ meetings and driving. In other words, my distance, mid-range and close up vision all need to be sharp. Blended laser vision correction has worked really well for me.”