Amblyopia

What is it?

A person with amblyopia, or ‘lazy eye’, has a condition, in which the message sent from the affected eye or eyes to the brain is of low quality, making the sight of the eye poor. Sometimes the phrase ‘dimness of vision’ is used to describe amblyopia. A person with amblyopia will have poor vision, which cannot be simply corrected with spectacles.

 


 

What causes amblyopia?

Amblyopia has many different causes. Generally, if a person cannot easily maintain both eyes working together, amblyopia will result in one eye. Common causes of this are a turned eye or a large difference in the extent of shortsightedness or astigmatism (refractive error),or for large degrees of long-sightedness in both eyes.

How do these factors lead to amblyopia?

Normally the message sent to the brain from both eyes is similar. In the person with amblyopia, the message received by the brain from one eye is weaker than the message from the other eye.

This has been caused by the brain having difficulty working with the image or alignment of the eyes. To reduce this difficulty to a managable level the brain ignors the message from one eye. The affected eye tends to be used less for detailed sight and further weakening of the eye to brain links result.

Although the basic components of the visual system are present at birth, a child’s visual system continues to develop after birth in response to his or her visual environment. This development progresses rapidly in the first few years of life and continues until at least the age of seven years.

If a child’s visual system is not properly stimulated during these early years, lack of development may result in a permanent or long-term problem.

Amblyopia may follow in families and children under 2 years of age should be assessed for this.

How common is amblyopia?

Up to four percent of the population have amblyopia.

How can I tell if my child has amblyopia?

The most important sign is poor vision, but because only one eye is affected and the other eye usually does the work of both, parents often are unaware of the problem. Other clues are a noticeable favouring of one eye, a ‘turned’ eye and bumping into objects on one side of the body.

A full eye examination is the only sure way of finding out if your child has amblyopia. If you think that there may be something wrong with your child’s vision, talk to your Optometrist.

When there is another family member who has poor sight in one eye, even with glasses or contact lenses then all children in the family should be examined.

How is amblyopia treated?

The treatment depends on the particular cause of the amblyopia.

Most commonly glasses, prisms, contact lenses and vision therapy programs are used to coordinate the poor eye’s visual function. Sometimes the better eye is covered for short periods to force the lazy eye to be used. Treatment requires effort by the child and family for 3-12 months. The earlier amblyopia is detected, the more effective the treatment is likely to be.

Can amblyopia be treated as an adult?

Improvement is possible at any age but takes significantly longer after 10 years of age. It may not improve as much as for young babies and younger children. The earlier amblyopia is detected, the more effective the treatment is likely to be.

Why treat amblyopia?

The purpose of treatment is to promote the best sight in each eye. Without treatment some people will have reduced or little sight in one eye for their lifetime.