What are myopia, hypermetropia and astigmatism?

Often people say ‘I am long-sighted’ or ‘short-sighted’, but for a lot of us who don’t wear glasses sometimes it’s difficult to understand what this means.

Fancy long and complicated words like myopia and hypermetropia make this all the more confusing.

Does short-sighted mean you can see things up close or you can’t? What makes a person long-sighted? How can glasses, lenses or laser eye surgery correct this? We can help you find the answers to these questions!

Short sighted or long sightedness occur when a person’s lens cannot focus light entering the eye in the right way on the back of the eye, also known as the retina.

If you are short-sighted (also known as myopia) you can see things that are up close, but can struggle to see things further away. This is because light entering the eye is focused in front of the retina, when it should focus on the retina. It focuses too soon. This happens for two reasons: either the lens focuses light too strongly or the eye is too ‘long’ meaning the retina is too far away from the lens. To correct this we give short-sighted people lenses that change (diverge) the way light enters the eye so once it is focused by their natural lens it focuses on the right place of the retina. These types of lenses are called minus, hence why short-sighted people get ‘minus prescriptions’.

Long sighted (also known as hypermetropia or hyperopia) is when you cannot see things up close. It’s exactly the opposite problem to short sightedness. This happens when light entering the eye is focused behind the retina; you can think of it like the eye focuses light too late. This happens when either the eye is too short and the retina is too close to the lens, or when the lens focuses light too weakly. To correct this we give long-sighted people lenses that converge the light that enters the eye so once it is focused by their natural lens it focuses on the right place of the retina. These types of lenses are called plus, hence why short-sighted people get plus prescriptions’.

Another term that we hear quite often when talking about disorders of the eye is astigmatism. It is caused by abnormalities in the cornea and the lens. Astigmatism can be described as the condition when the front of the eye is not a perfect round shape like a football, instead it is more oval like a rugby ball. This gives the front of the eye an asymmetric curvature so light scatters as it goes into the eye. This produces a jagged and slightly distorted image.

Some people are unlucky enough to have astigmatism as well as long or short-sightedness. Luckily short-sighted and long sighted don’t often happen together. But some people when getting older may get one eye short sighted and another one long sighted. Optometrists may leave these patients with uncorrected vision if they feel comfortable and would find glasses an inconvenience.

Fortunately, the wonders of modern medicine and technology mean there are many amazing ways to correct long or short sightedness! Glasses can be a low cost and even stylish solution, contact lenses although not always ideal can be a practical one. But there are even more exciting and amazing ways that vision correction can done now.

At My-iClinic our specialists are experts in two types of procedures that can cure long or short sight and astigmatism: laser eye surgery or refractive lens exchange.