What is Amblyopia?

Amblyopia (lazy eye) is poor vision in an eye that did not develop normal sight during early childhood. Usually, only one eye is affected by amblyopia but occasionally, both eyes can develop amblyopia. This condition is common, affecting up to 3% of all people.

Causes of amblyopia

Normal visual experience is essential for normal vision development in children. If a child is deprived of normal visual experience during early childhood (up to first 8 years of life), the affected eye(s) may develop amblyopia.

The causes of amblyopia includes

  1. Strabismus (Squint).  Amblyopia occurs commonly with misaligned or crossed eyes. The crossed eye “turns off” to avoid double vision and the child only uses the better eye. Thus the misaligned eye fails to develop good vision.

  2. Unequal focus/ refractive error. Refractive errors are conditions that are corrected by wearing glasses. If one eye has higher refractive error (i.e. more out of focus) and is uncorrected with glasses, the unfocussed eye is blurred and becomes amblyopic.

  3. Cloudiness in the normally clear eye tissues. An eye disease such as cataract (clouding of the naturally clear lens in the eye) may lead to amblyopia unless the eye receives urgent treatment.

Diagnosis of amblyopia

It is not easy to recognize amblyopia. A child is usually not aware of having one strong eye and one weak eye since both eyes are used together. Unless there is a misalignment of one eye, a parent seldom realizes that something is wrong. Diagnosis of amblyopia is usually made by trained eye professionals such as ophthalmologists (medical doctors who specialize in eye diseases), optometrists and orthoptists. A trained eye professional will perform a detailed examination on the child’s eyes and will commence the appropriate treatment for any eye conditions that may exist. It is therefore important to have the eyes of children check routinely by qualified professionals.

Treatment of amblyopia

To correct amblyopia, the child must be made to use the weak eye. The treatment of amblyopia involves the following steps.

  1. Treatment of the underlying cause. Any underlying causes for the weak eye must be treated. For example, glasses are prescribed for existing refractive errors. Eye conditions such as squint or cataract must be treated appropriately.

  2. Occlusion therapy (patching). Occlusion or patching of the strong eye is done to make the child use the weak eye. The patching may last from a few weeks to a few months.

  3. Medication. Some children do not cooperate with patching may benefit from a dilating eye drop instilled in the strong eye. The eye drop reduces the ability of the strong eye to focus thereby blurring its vision making the child use the weak eye.

If amblyopia is not treated, several problems may occur.

  1. The amblyopic eye may develop serious and permanent visual defect.

  2. Depth perception (seeing in three dimensions) may be lost.

  3. If the good eye becomes diseased or injured, a lifetime of poor vision may be the result.

Children do not like to have their eyes patched. Therefore it is important for parents to convince the child to do what is best for him or her. The parents’ interest and involvement is crucial for successful treatment.
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