INTRODUCTION

Amblyopia (also called lazy eye) is a type of poor vision that happens in just 1 eye. It develops when there’s a breakdown in how the brain and the eye work together, and the brain can’t recognize the sight from 1 eye. Over time, the brain relies more and more on the other, stronger eye — while vision in the weaker eye gets worse.

It’s called “lazy eye” because the stronger eye works better. But people with amblyopia are not lazy, and they can’t control the way their eyes work.

Amblyopia starts in childhood, and it’s the most common cause of vision loss in kids. Up to 3 out of 100 children have it. The good news is that early treatment works well and usually prevents long-term vision problems.

SYMPTOMS

Amblyopia starts in childhood, usually between ages 6 and 9. Identifying and treating it before age 7 brings the best chances of fully correcting the condition.

Common symptoms include:

• Trouble telling how near or far away something is (depth perception)
• Squinting or shutting one eye
• Head tilting

CAUSES

• Refractive errors. One eye might have much better focus than the other. The other eye could be nearsighted or farsighted. Or it could have astigmatism (distorted or blurry vision). When your brain gets both a blurry image and a clear one, it starts to ignore the blurry one. If this goes on for months or years, vision in the blurry eye will get worse.
• Strabismus. This is when your eyes don’t line up the way they should. One could turn in or out. People who have strabismus can’t focus their eyes together on an image, so they often see double. Your brain will ignore the image from the eye that isn’t aligned.
• Cataracts. A cloudy lens inside your eye can make things look blurry. The vision in that eye might not develop the way it should.
• Droopy eyelid (ptosis). A sagging eyelid can block your vision.

RISK

A child might be more likely to have a lazy eye if they:

• Were born early (premature)
• Were smaller than average at birth
• Have a family history of amblyopia or other eye conditions
• Have developmental disabilities

DIAGNOSIS

Ophthalmologists diagnose amblyopia by checking to see if vision differs between the two eyes. To check a baby's or young child's vision, the ophthalmologist may cover one of the child's eyes and watch how well they can follow a moving object. The doctor may also watch how the child reacts when one eye is covered. If one eye has amblyopia and the other is covered, the child may try to look above or below the patch, pull it off or cry.

The ophthalmologist will do a complete medical eye exam, looking for other eye problems that could be affecting vision.

Poor vision in one eye does not always mean a child has amblyopia. In some cases, wearing glasses to correct a refractive error in one eye can improve vision.

TREATMENT

If there’s a vision problem causing amblyopia, the doctor may treat that first. For example, doctors may recommend glasses or contacts (for kids who are nearsighted or farsighted) or surgery (for kids with cataract).

The next step is to re-train the brain and force it to use the weaker eye. The more the brain uses it, the stronger it gets. Treatments include:

Wearing an eye patch on the stronger eye. By covering up this eye with a stick-on eye patch (similar to a Band-Aid), the brain has to use the weaker eye to see. Some kids only need to wear the patch for 2 hours a day, while others may need to wear it whenever they're awake.

Putting special eye drops in the stronger eye. A once-a-day drop of the drug atropine can temporarily blur near vision, which forces the brain to use the other eye. For some kids, this treatment works as well as an eye patch, and some parents find it easier to use (for example, because young children may try to pull off eye patches).

After your child starts treatment, their vision may start to get better within a few weeks. But it will probably take months to get the best results. After that, your child may still need to use these treatments from time to time to stop amblyopia from coming back.

It’s important to start treating children with amblyopia early — the sooner the better. Kids who grow up without treatment may have lifelong vision problems. Amblyopia treatment is usually less effective in adults than in children.