Lazy eye (Amblyopia)

What is amblyopia or 'lazy eye'?

Amblyopia is an eye condition where the brain 'turns off' or ignores the input from one eye. However, in some complex cases amblyopia can happen in both eyes. It’s one of the most common causes of visual problems in young children. The brain can only learn to see as clearly as the picture given to it by the eyes. If the brain has not been given a sharp, clear picture by the eye because of astigmatism then it cannot learn to see clearly. If spectacles are worn to help focus the light then amblyopia may be prevented.

As children grow, we see how they learn to interact with the world around them. It can be worrying as a parent or teacher when we notice a child struggling to read or write, for example, especially when it’s difficult to pinpoint the problem.

What causes a ‘lazy’ eye?

During the first years of a child's life, the visual system in the brain is constantly developing. If the vision of any eye is interfered with, the brain will automatically favour one eye over another, resulting in vision loss in the less favoured eye. 

In a normal vision system, the brain receives an image from each eye and it merges these together to form one complex image. The two images are slightly different and slightly apart, and this difference creates 3D vision. But, if the two images are very different in size (aniseikonia) and/or too far apart (strabismus), the brain can't merge the two - resulting in double vision. 

Our brains aren’t able to process double vision, so instead they 'turn off' the signal from one eye - usually the non-dominant one. Once turned off, this eye will not function properly - hence the term 'lazy' eye. If this happens during the critical stages of growth and development of the eye (from birth to 8-12 years old), it can cause permanent vision loss in the lazy eye. That’s why it’s important to pick up any vision issues as early as possible and intervene promptly with treatment.

There are a variety of reasons that amblyopia may develop in a child, such as: 

• Strabismus (turning eye) 

• Visual deprivation

• Refractive errors

• Family history 

• Undiagnosed amblyopia

How does a lazy eye affect my child’s vision?

The most common symptoms of lazy eye are the eyes drifting apart and misalignment. However, a lazy eye can cause some serious vision problems, such as:

• Rapid loss of visual ‘sharpness’ in the lazy eye, especially if it’s left undiagnosed, uncorrected and increasingly unused.

• Loss of binocular vision (being able to focus on an image with both eyes), leading to the inability to gauge depth of field.

• Increase risk of vision loss for the stronger eye, since vision problems that typically occur in both eyes will begin with affecting the stronger eye.

Treatment

Traditional treatments for amblyopia consist of turning off the good eye and forcing the lazy eye to work, and this is known as penalisation therapy. This is often in the form of putting an eye drop in or an eye patch over the strong eye and forcing the lazy eye to work. 

Newer research indicates that rather than promoting one eye over the other, encouraging the two eyes to work better together is more effective at resolving amblyopia. This is known as dichoptic or binocular therapy. 

Patch-free lazy eye treatments:

- An effective dichoptic treatment for aniseikonia-related amblyopia is specialised aniseikonic lenses, called Shaw Lenses.

- An effective dichoptic treatment option for strabismus-related amblyopia is vision therapy.

- Atropine eye drops can be used daily in the dominant eye to blur the vision to encourage the "lazy" eye to work harder. 

Often, these treatment options will be used in conjunction with each other and/or with the traditional penalisation treatments. Your optometrist will recommend tailored treatment options, based on your child’s eyes and requirements.

FAQs

How early can you detect Amblyopia? Signs of amblyopia can be picked up in infants. At OCULA, we offer an InfantSEE program for children up to the age of 2, to ensure you have peace of mind for your child's eye health from a young age.

Can you prevent amblyopia? Yes, by having regular eye tests from a young age, you can detect eye conditions such as amblyopia, early on. This means you can start treatment for the eye condition in its early stages; which can be simpler than if left untreated for a long time.

Is my child at risk of getting a lazy eye? Some children are born with amblyopia, for others it develops later on during childhood. If your child has one of the following, they could have a higher chance of having amblyopia:

• If they were born premature

• If they were considered a small baby at birth

• If there is a family history of amblyopia, childhood cataracts or another eye condition

• If they have developmental disabilities

If you or someone else is concerned about your child's vision, please speak to your doctor, plunket or make an appointment to come in and speak to one of our team.

Will amblyopia get worse with age? If left untreated, vision in the lazy eye will progressively get worse, and you or your child’s vision will be reliant on the stronger eye.

Can a child grow out of amblyopia? It is very rare that a child will grow out of amblyopia. It is more than likely that the condition will worsen, if left untreated. 

Aniseikonia vs Strabismus, what’s the difference?

Aniseikonia occurs when the perceived image of each eye is in different sizes. Often, this is because each eye has a different prescription - just because they’re a pair, it doesn’t mean both eyes are the same. For example, one eye might be significantly more short-sighted (myopia), or long-sighted (hyperopia) than the other, so one eye is essentially ‘seeing’ different to the other.

Strabismus or “cross eye” is a misalignment of the eyes, when the muscles surrounding the eyes (that also help them focus), aren’t working properly together. It can be both a cause of and an effect of amblyopia.