Amblyopia

Amblyopia is when one of the eyes is lazy.

Amblyopia occurs between birth and 7/8 yrs old. It is when one of the eyes do not function or behave the same way as the other, and therefore is used less. The brain begins to ignore the less used eye, which leads to poor visual development in lesser-used eye. This results in a difference in vision and visual function between the two eyes.

Amblyopia can affect both eyes but is more rare.

Amblyopia is a vision development problem that occurs at a young age, which can be more difficult to detect when a child is very young and/or non-verbal. Common signs to look out for are; strabismus, when one or both eyes turn. If a child becomes distressed when covering one of the eyes, compared to the other. If a child cannot perform a simple visual task with one of the eyes compared to the other or protests to the good eye being covered.

Most importantly a child should be attending regular eye tests, to assess that they have normal vision and that both eyes work together. If they do have Amblyopia it would be detected & treated more quickly.

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Amblyopia can be caused by:

·      A squint (turn in the one of the eyes or alternates between the eyes, also known as strabismus)

·      A significant uncorrected prescription in one of the eyes compared to the other

·      Undetected or untreated blocking of visual light stimulation to one of the eyes i.e cataract (amblyopia may persist even after treatment)

There are three types of amblyopia, based on the underlying cause:

• Strabismic amblyopia/squint amblyopia. It is one of the most common causes. When one of the eyes has drifted in/out/up/down, this causes double vision, as the two eyes do not work together as a pair. The brain ignores the turned eye/squint, it ‘switches it that eye off’. The visual development of the turned eye is ignored which leads to amblyopia.  
• Refractive/anisometropic amblyopia. Where one of the eyes has a significant prescription compared to the other eye – unequal prescription in the two eyes. If the eye with the significant prescription is not corrected, the brain learns to ignore that eye and rely only on the other/better eye only, which then causes amblyopia. Early eye tests to detect this and spectacle correction will help avoid this.
• Deprivation amblyopia. One of the eyes has something that obstructs light from entering and being focused at the back of the eye, such as congenital cataract. This causes amblyopia in the obstructed eye. Any obstruction would need to be investigated and treated promptly

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·       Full vision correction with glasses or contact lenses

·       Treatment of squint/strabismus if present and vision therapy called orthoptics

·       Patching the good eye to get the weaker eye to work and be stimulated – patching time dependent on the severity of amblyopia and age of child

·       If the child cannot be patched, eye drops to blur the good eye can be used 

The outcome of treatment is dependent on how poor the vision is in the weaker/lazy eye, their age and how well the child takes to patch. The earlier amblyopia is caught (ideally before the age of 8 yrs old), alongside strong treatment adherence; the better the visual outcome.

Older children and adults with amblyopia may benefit from new computer programs that have been developed by doctors & researchers. The programs have been designed to stimulate neural changes, which has led to improved vision and contrast sensitivity in amblyopic patients.