In the United States, amblyopia affects 2 to 3 percent of all children. It is the most common cause of partial or total blindness in one eye.
Lazy eye, also known as amblyopia, is an early childhood condition in which a child’s eyesight does not develop as it should in one or both eyes.
The term “lazy eye” is misleading because the eye is not lazy. In fact, it is a developmental problem in the nerve connecting the eye to the brain, not a problem in the eye itself.
“Amblyopia cannot have obvious signs within the eye. It is more of a brain problem. This is due to vision loss because the connections between the neural pathways between the brain and the eye don’t get the proper sensory input during childhood,” said Vision Boutique Optometrist Ashley Setterberg.
Signs and symptoms of lazy eye include: head tilting, eye wanders inward or outward, squinting or shutting an eye and poor depth perception.
“This is quite common. It is actually the leading cause of vision loss in children. They estimate 2 to 3 children out of 100 are affected by this,” said Setterberg.
Early recognition and treatment of the problem in children can help to prevent permanent visual loss.
“This can be prevented by having an eye exam and wearing proper glasses that are needed or surgery for strabismus. In addition, there are a few other causes of this, and surgery usually can correct and prevent it from occurring. If it does occur though, amblyopia can be managed and maybe even fully successfully treated if started early enough in childhood,” said Setterberg.
But if left untreated, lazy eye can cause severe visual disability in the affected eye, including legal blindness.
Symptoms of amblyopia can often be confused with other visual impairments, namely crossed eyes.
The crucial time to diagnose amblyopia is during infancy, before the condition becomes more severe.
Look for the following signs to determine if you or your child has amblyopia:
- Head tilting
- An eye that wanders inward or outward
- Eyes that appear to not work together
- Poor depth perception
- Squinting or shutting an eye
What Causes Amblyopia?
There are three types of amblyopia, based on the underlying cause:
- Strabismic amblyopia. Strabismus is the most common cause of amblyopia. To avoid double vision caused by poorly aligned eyes, the brain ignores the visual input from the misaligned eye, leading to amblyopia in that eye (the “lazy eye”). This type of amblyopia is called strabismic amblyopia.
- Refractive amplyopia. Sometimes, amblyopia is caused by unequal refractive errors in the two eyes, despite perfect eye alignment. For example, one eye may have significant uncorrected nearsightednessor farsightedness, while the other eye does not. Or one eye may have significant astigmatism and the other eye does not.
In such cases, the brain relies on the eye that has less uncorrected refractive error and “tunes out” the blurred vision from the other eye, causing amblyopia in that eye from disuse. This type of amblyopia is called refractive amblyopia (or anisometropic amblyopia).
- Deprivation amblyopia. This is lazy eye caused by something that obstructs light from entering and being focused in a baby’s eye, such as a congenital cataract. Prompt treatment of congenital cataracts is necessary to allow normal visual development to occur.
- Symptoms of lazy eye include blurred vision and poor depth perception.
- Lazy eye is not a problem with the eye, but the connections to the brain.
- Amblyopia can be caused by a number of factors, including a muscle imbalance or eye disease.
- Treatment can be effective and the sooner it begins, the better.
Amblyopia is a relatively common problem.
Treatment tends to be more effective the younger the child is.
After a child is 8 years old, the likelihood of vision improvement drops significantly but can still be effective.
There are two approaches to lazy eye treatment:
- treating an underlying eye problem
- getting the affected eye to work so that vision can develop
Treatment for underlying eye problems
Many children who have unequal vision, or anisometropia, do not know they have an eye problem because the stronger eye and the brain compensate for the shortfall. The weaker eye gets progressively worse, and amblyopia develops.