As many as four percent of children in the US are affected by amblyopia and, if not treated, those children will become amblyopic adults. Many patients are more familiar with the term “lazy eye”, but that term can also be confusing and doesn’t quite cover the potential implications of amblyopia. So what’s the big deal? We use our sight for most daily tasks from work, to hobbies, to errands, and when learning. Amblyopes must work extra hard at all of these tasks because their visual system doesn’t work as well for them.

This article covers important information about amblyopia that everyone needs to know.

So What Is “Lazy Eye”, Really?

“Lazy eye” is a colloquial term that is often used to describe an eye that turns. This turn can be inward or outward, but, in rare cases, the eye will turn up or down. On occasion, “lazy eye” is also described as an eye that doesn’t see as well as the other. In essence, “lazy eye” describes both strabismus and amblyopia

An Important Definition for Refractive Error

Refractive error describes a condition where light cannot be clearly focused on the back of the eye. This is often due to the size and shape of the eye. Nearsightedness, farsightedness, and astigmatism all fall under the umbrella of refractive error.

Let’s Dive Into the Details of Amblyopia

What Is Amblyopia?

Per the American Optometric Association, “amblyopia is the loss or lack of development of clear vision in one or both eyes.” This means that one or both eyes are not seeing as well as they should be seeing simply because they haven’t had the practice and not because of any eye disease.

What Causes Amblyopia?

Our visual system relies on input from our eyes, which is then processed by our brain. During infancy and childhood, our brain essentially learns how to see. However, if the brain is given “bad” information, it won’t learn to see properly.

There are several causes of amblyopia but they are all related to some sort of deprivation of the visual system:

Uncorrected Refractive Error: An high uncorrected refractive error in one or both eyes will cause amblyopia. Eye care professionals know exactly where the “dangerous” range of refractive error begins and will recommend glasses for full-time wear.

An Eye Turn: An eye turn that is persistent will cause the brain to block out the “bad information” from that eye. Just as the brain prefers a clear image, it also prefers to see “straight ahead”. On the other hand, if the eye turn is intermittent, meaning that it comes and goes, the brain will cherry-pick information and is more likely to build those neural connections

An Obscured Line of Sight: The obscuration can be due to prolonged patching of the eye or due to a congenital cataract that is treated too late in the child’s life- after the visual system has already begun to develop.

How is Amblyopia Diagnosed?

For eye care professionals, amblyopia is a diagnosis of exclusion. This means that an eye doctor will first carefully check eye health to make sure that no other ocular diseases are present that can account for the vision loss.

How is Amblyopia Treated?

Your eye doctor may recommend glasses, patching, prisms, and vision therapy to help rehabilitate an amblyopic eye.

The best way to successfully treat amblyopia is to catch it early. Children’s visual systems are particularly sensitive until puberty and this is thought to be the best time to treat amblyopia. The younger the child, the greater the chances of success.  This is perhaps why the American Optometric Association recommends an eye exam at six months of age and then another by three years of age to ensure that amblyopia-causing refractive errors are detected in a timely manner.

Unfortunately, treating amblyopia in teenagers and adults is much more challenging. However, anecdotal evidence from eye care professionals suggests that even adults will improve with consistent correction and visual therapy.

A Note on Patching

Your eye care provider will generally recommend patching if one eye is amblyopic, ie seeing more poorly than the other. Patching involves obscuring vision in the “better” eye to give the “worse” eye some practice; the brain must rely on the “bad” eye and will work harder to relearn how to see. If your eye doctor recommended patching and you’re struggling, you’re not alone- there are many support groups for parents and children including the Truffles the Kitty Organization.

You should also tell your eye doctor that you’re having trouble with patching; your eye doctor may offer alternatives such as atropine drops to blur vision in the “better” eye.

Eye Care Provider Tip: Ambylopes respond best to single letters versus a line.

With a better understanding of amblyopia, patients, eye care providers, and even other health care providers can work together to help ensure that amblyopia is caught early and treated successfully.

Stay tuned for part 2, which will focus on strabismus.

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