Amblyopia (A Lazy Eye)

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This leaflet is intended to answer some of the questions of carers of patients diagnosed with Amblyopia under the care of University Hospitals Sussex NHS Foundation Trust.

Amblyopia (Am-blee-oh-pee-ya) literally means “dimness of vision”.

What is wrong with my child’s eyes?

Seeing is done not only by the eyes but also by the brain. A picture enters the eye and a signal is sent through a nerve (the optic nerve) at the back of the eye into the brain and it is this which we interpret as “vision”. In amblyopia the eyes are healthy, but visual information coming from one or both eyes is not clear and is not recognised properly in the brain.

Were they born this way?

Children are not born with perfect vision; this develops over time up until the age of around eight years old.

In order for vision to develop normally the picture coming through the eye and into the brain must be clear so that the brain and the eye can “learn to see”. If it is unclear or absent then the part of the brain responsible for seeing with that eye will fail to develop normally.

If the eyes are healthy then why don’t they see well?

The connections between the eye and the brain which allow us to recognise clear vision need to develop.

The eyes and brain are physically healthy, but, if they are not stimulated by a clear picture entering the eye then the cells in the brain cannot grow and develop.

Why is the picture entering the eye not clear?

There are several reasons that the picture coming through the eye may be unclear and cause amblyopia.

The most common are:

Uncorrected refractive error (need for glasses).
Strabismus (where the eyes are not properly aligned).
A droopy eyelid.

Other less common reasons may be:

• A childhood cataract.

How is their vision affected?

This varies depending upon the cause of the amblyopia and how long the condition has been left untreated. The longer the condition is undetected the worse the vision is likely to be.

Does it affect both eyes?

Most often amblyopia affects only one eye, but it can affect both, particularly in children who are very long or short sighted in both eyes.

Can it be treated?

Yes. The first line of treatment is to give glasses if needed; this will make the picture entering the eyes clear.

It can take up to 18 weeks for children to fully adapt to glasses and for some children this is the only treatment.

If no glasses are needed, or if the amblyopia is still present after children are fully adapted to their glasses then the orthoptist will prescribe “occlusion therapy” or “patching” as it is known. This is the principle of covering the better eye to encourage the “lazy” eye to work harder and to stimulate the eye and the brain.

Your child will be reviewed frequently to ensure their vision is responding to treatment.

Are there any other treatments?

If patching treatment is not effective we can consider using eye drops in some cases. This can be discussed on an individual basis with your orthoptist.

If the amblyopia is caused by a cataract or droopy eyelid then some children may need surgery to remove or reduce this.

What will happen if no treatment is given?

If treatment is not given before the age of eight then vision loss from amblyopia is permanent. It is important to carry out the treatment as instructed by the orthoptist and attend appointments so that the treatment can be adjusted according to your child’s progress.

If you are unable to attend you must contact the department.