Amblyopia, also known as lazy eye, means you can’t see properly with one of your eyes. The condition normally starts when you are young and your eyesight is still developing. It usually affects just one eye, although rarely it can affect both. If the condition is not recognized and treated in childhood you will have blurred vision for life.

Lots of things can cause amblyopia and how it is treated depends on the cause. The main thing is to treat the problem as early as possible so the eyesight is not permanently damaged.

What causes amblyopia and who can get it?

You see things when light rays travel through the front of your eye (cornea and lens), and form images on the light sensitive surface at the back of your eye (retina). Your retina then sends messages to your brain so you can recognise the objects you are seeing.

When you are young and your eyesight is still developing (up to the age of eight) it is important that this all happens normally, with clear images being formed in your eye and sent to your brain, so your vision develops normally.

If the picture on your retina is blurred as your eyesight develops, it can cause you to have poor vision or amblyopia.

There are lots of different eye disorders that can cause amblyopia. All of them cause a blurred image on the retina of one or both eyes. Such disorders include:

• Short-sightedness (myopia)
• Long-sightedness (hypermetropia)
• Astigmatism (where the surface of the lens is uneven, causing blurred vision)
• A congenital cataract (clouding of the lens of the eye present from birth)
• A squint (strabismus) in one eye can have a more serious effect on your long term vision.

What are the signs and symptoms of Amblyopia?

With amblyopia your affected eye can't send normal signals to the brain, so the main symptom of a lazy eye is blurred vision. This might not be obvious if only one of your eyes is affected because your vision with both eyes open is normal. There are usually no physical signs although sometimes you may have a noticeable squint, droopy eyelid, or a cataract when there is clouding of the lens of your eye.

It can be difficult to know when young children have amblyopia because they often do not realise there is anything wrong with their vision. It is often diagnosed when you have your first eye test before you start school.

How is it normally diagnosed and treated?

If an eye specialist (ophthalmologist) suspects a lazy eye, a full eye examination will be carried out.
Each eye will be tested separately to measure how well it can see and to find out whether there is any serious long or short sightedness. Then the eye position will be carefully assessed to find out if they are misaligned. The structure of the eye may also be examined to see if there are any abnormalities, such as cataract.

Treatment aims to put right any eye problem that is causing the amblyopia. For example, long or short sightedness can be corrected using glasses.

Some treatments try to make the lazy eye work. A patch can be placed over your good eye (a treatment called occlusion) or eye drops can be used to blur your vision in your good eye so that your lazy eye is forced to work.

If the condition is caused by another problem, such as a squint or a cataract, surgery may be needed.

What’s going to help?

Early diagnosis and treatment is the most important thing with amblyopia.

If amblyopia is not treated at an early age the central vision, in one or both eyes, may not develop properly. This means everyday things you do, like reading and writing, would be difficult in the amblyopic eye.

Looking forward

Provided everything is treated early enough, amblyopia should not have any long term affect on your vision.

It is important to carry on being aware of your eyes throughout your life and to keep them healthy. Get your eyesight checked regularly by an optician.

For more help and information

Please ask your doctor If you would like to know more about amblyopia.

You may also find useful help and information at the following websites:

• RNIB
• Moorfields eye hospital

Last reviewed by Great Ormond Street Hospital: 27 September 2007

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