What Is Amblyopia (Lazy Eye)?

Vision is a complex sense. In order to see properly, the different parts of the eye need to work together to transmit information to the brain. The brain then has to interpret the information into shapes and colors so that you can see. If one part in this chain stops working, you can have vision changes or even vision loss.

The parts of the eye have to learn to communicate with one another — a process that takes several years to perfect. The occurrence of certain eye conditions during childhood can interrupt this communication process. If the eye and brain don’t learn to communicate properly, a child can develop trouble seeing or even vision loss. This is called amblyopia.

Even though a child with amblyopia has decreased vision in one eye, the affected eye can look totally normal. So how can you tell if your child is having trouble seeing from one eye? And when should they see an eye doctor? We’ll address these questions and more with a deep dive into amblyopia. 

What causes amblyopia (lazy eye)?

Amblyopia develops when the brain and eye don’t learn to communicate properly. This communication process begins at birth and is perfected around a child’s seventh birthday. You may have heard the term “lazy eye” used to refer to amblyopia. Healthcare providers, parents, and children with amblyopia usually prefer not to use this term.

There are several conditions that can lead to amblyopia, including:

• Strabismus (crossed or misaligned eyes)

• A droopy eyelid (ptosis)

• Congenital cataracts

• Refractive errors (uncorrected nearsightedness, farsightedness, or astigmatism)

• A hemangioma on the eyelid

How does amblyopia affect vision?

Amblyopia develops because the brain doesn’t understand the signals it’s receiving from the eye. This can happen because the signals are blurry (like with nearsightedness) or doubled (like with strabismus).

Because the brain can’t understand the signals, it essentially stops listening to them. So even though the eye is receiving images, the brain isn’t interpreting them.

Amblyopia can also develop if the brain doesn’t get any signals from the eye. This can happen with a congenital cataract. Basically, since the brain isn’t getting any information, it stops listening to the eye.

Whatever causes amblyopia, the result is a decrease in vision and depth perception — even though the eye itself is usually working properly. 

Who is most at risk to develop amblyopia?

Some children are more at risk of developing amblyopia, including those who were born prematurely or those with a parent or sibling who had or has amblyopia.

But amblyopia is pretty common. Studies estimate that 3 to 5% of children worldwide have decreased vision because of amblyopia. 

How do you know if your child has amblyopia?

It’s really hard to tell if your child has amblyopia. Children learn to rely on their “good,” or unaffected, eye to navigate the world. Children are so good at adapting to this that many children go years with decreased vision before their amblyopia is diagnosed.

Sometimes, children show signs of amblyopia, such as:

• Squinting

• Closing one eye when looking at objects

• Tilting their heads when looking at something or going down stairs

• Trouble catching or throwing objects, which is a sign of poor depth perception

But most children don’t show any signs at all. That’s why a childhood vision exam is important. An eye doctor will be able to tell if your child has amblyopia, or a condition that can cause amblyopia, with an eye exam.

Your child should have an eye exam at least once between ages 3 and 5. But if you think your child is having trouble seeing, see an eye doctor as soon as possible. 

Will amblyopia go away on its own?

Amblyopia will not go away on its own. Your child can’t “grow out of it,” but treatment can improve vision. Children who start treatment early do better than those who start later. 

What are current treatments for amblyopia?

Your child’s eye doctor will start by treating the condition that led to the amblyopia. That might mean removing a cataract or correcting a refractive error. In most cases, children will also need to use glasses (or contact lenses). If your child has mild vision changes or is very young, that can be enough to reverse their amblyopia.

Older children and children with more severe vision loss will need additional treatment. This treatment focuses on reestablishing communication between the brain and eye. This is done by forcing the brain to listen to the eye with amblyopia, by silencing signals from the unaffected eye.

How is that accomplished? It’s actually pretty simple: Your child will wear a bandage, sometimes called a patch, over their unaffected eye for a certain amount of hours each day.  Their eye doctor will determine the amount of hours, which is different for every child.

Some children can use atropine eye drops instead of a patch. Atropine works by dilating the pupil, which causes blurry vision.

While it takes a long time for the brain and eye to learn to communicate, retraining takes a relatively short amount of time. Most children have improved vision within a few weeks. 

Still, retraining can feel like a slow process: It’s frustrating when there aren’t quick results. Even though it can be a challenge to get a preschooler to keep a patch on, don’t give up! Keep trying, because every minute they keep it on is a win for their visual recovery.