Lazy Eye (Amblyopia): Symptoms, Causes and Treatment

What is Amblyopia (Lazy Eye)?

Amblyopia, also called lazy eye, refers to an eye condition in which there is one weaker eye. The weaker eye develops during infancy or early childhood.¹

Because the brain relies on the stronger eye, a lazy eye worsens over time. It can also significantly affect vision.

While difficult to deal with, amblyopia is very common. It’s the most frequent cause of vision loss in children. It affects up to 3 out of 100 children.¹

There are various types of lazy eyes that have different causes and treatment needs. Whatever the root cause, early diagnosis of amblyopia is vital to reduce further vision problems.

3 Types of Lazy Eye

There are three main types of lazy eye:

1. Refractive

A refractive lazy eye refers to major differences in vision between both eyes.² You may see clearly in one eye but not the other.

2. Strabismic

A strabismic lazy eye is when there is constant eye turn in just one eye.¹

3. Deprivational

A deprivational lazy eye is when there are vision abnormalities in one eye due to issues like cataracts or structural problems.

What Causes Lazy Eye? 

Some children are at a higher risk of developing a lazy eye. These include children who have:¹

• A family history of vision issues
• Developmental disabilities
• Complications at birth (including premature birth)

There are several types of vision issues that can cause a lazy eye, with or without these risk factors:

Refractive Errors

Certain refractive errors can cause a lazy eye. They include:⁸

• Nearsightedness (myopia) refers to difficulty seeing objects at a distance
• Farsightedness (hyperopia) refers to trouble seeing things up close
• Astigmatism refers to a curve in the cornea that causes blurred or distorted vision

Crossed Eyes

Crossed eyes, also known as strabismus, can lead to other eye problems like amblyopia. 

If one eye is constantly drifting, the brain might start to depend on the other eye. When this happens, a lazy eye can develop.

Physical Eye Problems

Some physical eye problems can also affect vision or cause vision loss. These include cataracts, droopy eyelids, eye injuries, and other issues.

Other Symptoms of Lazy Eye

Symptoms of a lazy eye range in severity. While some symptoms may go unnoticed, others are more obvious.

Here are some symptoms to be aware of:¹

• Crossed eyes
• Droopy eyelids
• Squinting eyes
• Blurry vision
• Frequent head tilting
• Differences in vision strengths between the eyes
• Favoring one eye

Other symptoms that might accompany a lazy eye, and can be a byproduct of the condition, include:

• Eyestrain
• Headaches
• Trouble reading
• Difficulty concentrating

When to See a Doctor

See a doctor if you are experiencing worsening vision issues. Here are some examples:

• Your vision issues are making it difficult to see and dangerous to get around
• Your lazy eye is getting worse, which may cause discomfort, among other symptoms
• The symptoms of your lazy eye are not improving with treatment 

Diagnosis

Your doctor can diagnose a lazy eye with a simple vision check. You should also attend annual eye exams to check for any eyesight changes.⁵

Treatment

There are several ways to treat a lazy eye. Here are four options:

• Wear an eye patch over the strong eye to force the weaker eye to become stronger. The brain will have to rely on it to see.⁶
• A Bangerter filter is an alternative to an eye patch. It’s a filter that fits on the inside of an eyeglass lens. It is worn over the dominant eye to create the same effect.⁶
• Apply atropine eye drops to the stronger eye to blur vision temporarily. This also forces the brain to focus on the weaker eye, making it stronger over time.⁶
• Wear eyeglasses and contact lenses to correct vision. An eye doctor will have to give you a prescription to treat your particular case.⁶
• Vision therapy exercises like eye movement control and strengthening techniques.

Outlook

Without lazy eye treatment, vision can worsen. With treatment, vision will improve significantly. The earlier you treat a lazy eye, the better.

Can You Prevent Amblyopia? 

Some lazy eyes are preventable. For example, if you have crossed eyes or a structural eye problem, you may be able to treat it before it leads to amblyopia.

For some children, a lazy eye is inherited. In these cases, treatments like eye drops or eye patches can help strengthen the weaker eye. But the lazy eye might always be slightly weaker than the other.

Summary

Amblyopia is very common, especially if you have a family history of eye problems. Having one weaker eye can cause blurred vision and other issues.

It is important to treat amblyopia as early as possible. An eye exam can diagnose this condition. Once your eye doctor understands what is causing your lazy eye, they will determine the best treatment for your needs.