A Simple Guide to Amblyopia

A Simple Guide to Amblyopia
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What is Amblyopia?
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Amblyopia, commonly known as ‘lazy eye’, is reduced visual acuity in one eye that appears normal on examination.
It usually develop during early childhood.
If left untreated, amblyopia will usually continue into adulthood.

What are the Causes of Amblyopia?
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1. Squint

Squint or misalignment of the eyes occurs when one eye is looking straight and the other is looking in another direction.
The vision from the deviating eye is suppressed.
The part of the brain that receives the vision from the deviating eye does not develop normally.
Therefore there is a severe reduction of vision in the deviating eye.

2. Different refractive powers of the eyes

A significant difference in the degree of short-sightedness, long-sightedness or astigmatism between the two eyes may result in failure to form clear image in the eye with the greater refractive error resulting in Amblyopia.

3. Blurred vision in one eye

This occurs with:
1.An opaque cornea
2.Cataract
3.Drooping upper eyelids due to weakness of the muscles that lift the eyelids
4.Eye trauma or eye surgery
5.Toxic causes such as arsenic, lead, smoking,vitamin B1 and B12 deficiency
6.Neurological causes are chiasmal lesions in the brain
7.Amaurosis: complete loss of vision in one eye occurs in uremia, nephritis and eclampsia
8.Psychological causes like hysteria

Symptoms may include:
1.decreased vision in one eye
2.squint
3.drooping eyelid

Diagnosis and Early detection

1.Amblyopia in young children can only be discovered if vision in each eye is tested separately.

Treatment is usually more successful if amblyopia is detected early especially before the age of four.

2.regular eye and vision tests should be done by the family doctor, paediatrician or ophthalmologist.

Treatment

1.underlying conditions causing the ‘lazy eye’ such as refractive errors, drooping eye lid or squint should be treated.

2.The main purpose of treatment is to cause the part of the brain that reads images from the ‘lazy eye’ to work more harder to read images than the better eye.
The earlier the treatment is started, the better is the results.
Once the child is over 8 years of age, he/she may not respond well to treatment, resulting in permanently impaired vision.

Treatment can be given in two ways:
1.Eye Patch
 An opaque, adhesive patch is worn over the better eye for weeks to months. This treatment forces the child to use the weaker eye and stimulate the brain to read the images in the weaker eye.
The main problem with the eye patch is that no child likes to have his eye patched. Parents need to ensure that the eye patch is worn properly as advised by the eye doctor.

2.Atropine eye drops
In some cases where the child cannot tolerate eye patches, a drop of atropine is instilled in the stronger eye once a day to blur the vision temporarily in order that the child will prefer to use the ‘lazy eye’.

Prognosis:

Amblyopia if left untreated can lead to loss of vision in the ‘lazy eye’.

Even with treatment 1% - 2% of the population will remain amblyopic. This occurs especially if:
1.the amblyopic stimuli is excessive
2.detection of amblyopia is too late;
3.the child responds poorly to treatment.

Even with one good eye the child can go about his life provided he/she takes good care of the good eye and protect it from harm.