What is lazy eye (amblyopia)?

What amblyopia is

The National Eye Institute (NEI) describes amblyopia as a type of poor vision that usually happens in just one eye, less commonly in both, where the brain can't recognize the sight from that eye [1]. Because the brain relies more on the stronger eye, the weaker eye is not used as much and its vision does not develop as it should. That is why glasses alone may not be enough and other treatment may be needed.

Clinicians often describe part of the problem as suppression: the brain turns down the signal from the weaker eye. Approaches such as patching aim to make the brain use the weaker eye more; dichoptic therapy aims to get both eyes working together.

How common it is

According to the NEI, up to 3 out of 100 children have amblyopia, and it is the most common cause of vision loss in children [1]. A 2020 meta-analysis of 60 studies estimated the worldwide prevalence at 1.44%, with higher estimates in Europe (2.90%) and North America (2.41%) than in Asia (1.09%) and Africa (0.72%) [10].

Causes

Doctors often cannot identify a specific cause. Underlying eye conditions that can lead to amblyopia include [1]:

• Refractive errors: nearsightedness, farsightedness or astigmatism, especially when the two eyes differ a lot (called anisometropia).
• Strabismus: eyes that are misaligned or turned.
• Cataracts: cloudiness in the lens that blocks a clear image from reaching the brain.

Symptoms

Amblyopia can be hard to notice, and many parents first learn about it from an eye exam. Signs the NEI lists include poor vision in one eye, poor depth perception, squinting, shutting one eye and tilting the head [1]. A child may not complain, because the stronger eye compensates.

Diagnosis

Amblyopia is diagnosed with an eye exam, often during a vision screening. The NEI recommends that all children between the ages of 3 and 5 have their vision checked at least once [1]. Only an eye care professional can tell you whether vision differences are caused by amblyopia or something else.

Standard treatments

Treatment usually starts by correcting whatever is causing the problem, then encouraging the brain to use the weaker eye. The NEI lists [1]:

• Correcting the underlying problem with glasses, contact lenses or surgery (for example for cataracts or strabismus).
• Patching: wearing an eye patch over the stronger eye.
• Atropine eye drops: special drops put in the stronger eye.

The NEI stresses that it is important to start treating children early: "the sooner the better" [1]. Which treatment is right, and for how long, is a decision for your eye doctor. Our treatment overview explains each option in more detail.

Amblyopia in adults

The NEI notes that treatment is usually less effective in adults than in children [1]. That does not mean an adult should not ask about it: an eye exam can confirm the diagnosis, rule out other causes, and your doctor can explain what improvement, if any, is realistic.

About ZyncView

ZyncView is a separate product from anything described on this page. It is a set of free browser games and a reading exercise for vision training and eye coordination, played with red/blue glasses. It is a wellness and entertainment product. It is not a medical device, it is not a treatment for lazy eye or any other condition, and it has not been tested in a published trial. If you are worried about your vision or your child's, see an eye care professional first. You can try the games or read how dichoptic games work.