Amblyopia (Lazy Eye)

amyblyopia / lazy eye

Also known as “lazy eye,” amblyopia (am-blee-O-pea) occurs when vision in one eye (or both eyes) is impaired because the eye and brain are not working together. Often the eye itself looks normal, but it is not being used normally because the brain is favoring the other eye. Amblyopia is the most common cause of visual impairment in children—two to three percent of children suffer from it. If left untreated, the lazy eye will persist into adulthood and lead to visual impairment.

There are several varieties of amblyopia:

  • Amblyopia secondary to Strabismus: Strabismus is the medical term used to describe eyes that are misaligned. Children’s brains are neuroplastic, which means they can easily adapt and eliminate problems such as double vision by suppressing images from one eye. But the plastic response to the brain results in amblyopia. Typically this form of amblyopia is treated with eyeglasses, or by placing an eye patch over the dominant eye to force the weaker, “lazy” eye to communicate with the brain.
  • Refractive or anisometropic amblyopia: A refractive error between the two eyes (anisometropia) may result in refractive amblyopia. The dominant eye is typically the one that provides the brain with the clearest image. When the image from the other eye is blurry, it results in an abnormal development of one half of the visual system. Amblyopia is often associated with a combination of strabismus and anisometropia.
  • Form-deprivation: Form-deprivation amblyopia is seen in children with eye problems such as cataracts. Like other conditions that create opacity (non-transparency or non-translucency) in the eye, cataracts prevent normal amounts of light from reaching the eye, which results in disrupted development. In this form, if it is not treated during the early stages, amblyopia can persist after the cause of the problem is removed.
  • Occlusion amblyopia: In occlusion amblyopia, the visual axis may be blocked due to a hemangioma (a benign tumor) or some other obstruction.

Symptoms of Amblyopia

Amblyopia can be mild or severe. In some mild cases, the affected person may not know they have the condition until they get older. This is because vision in the good eye is often strong enough to compensate for the lazy eye, allowing for normal vision. Symptoms of severe amblyopia may include:

  • Poor depth perception
  • Eyes that turn in or out
  • Eyes that obviously do not work together
  • Low sensitivity to contrast
  • Low sensitivity to motion

If you suspect amblyopia in yourself or your child, contact your eye doctor to set an appointment.

What Causes a Lazy Eye?

In most cases, a lazy eye is the result of an undeveloped nerve pathway from one eye to the brain during childhood. An affected eye sends blurry images (or sometimes wrong images) to the brain. This confuses the brain and may encourage it to ignore images from the weaker eye.  Typically, there is a family history of the condition. Additional causes may include:

Diagnosing Amblyopia

Unlike other eye conditions, amblyopia is easily diagnosed with a complete eye examination. Your eye doctor may ask you questions about the severity of your symptoms, your medical history, and your family history in order to make a correct diagnosis.

Amblyopia Treatment

Treating amblyopia typically involves treating the cause of the condition first. If cataracts are present, they will be treated. In some cases eyeglasses may be prescribed for farsightedness or astigmatism. It is common for an eye patch to be placed over the normal eye to force the brain to communicate with the weaker eye. Occasionally, instead of an eye patch, eye drops are used to blur the vision of the dominant eye. These eye drops are called Atropine, and they are quite safe for monitored regular use. Children will often refuse patching or Atropine treatment, but the parent must insist and take charge so that normal vision and depth perception can be restored.

In most cases, children under the age of five who receive adequate treatment usually recover almost completely, although depth perception may be a problem throughout the child’s life. Delayed treatment inevitably results in permanent vision damage. If the condition is not treated before the age of 10, partial recovery of vision is the best that can be expected.

Complications

If not treated in a timely manner, complications of amblyopia can include:

Preventing Amblyopia

Like many eye conditions, amblyopia can sometimes be prevented by recognizing the symptoms and beginning treatment during the early stages of the condition. If a child starts to develop the need for glasses and this is recognized early and treated, then anisometropic amblyopia won’t develop. Similarly, if a child is developing an occlusion, such as from a hemangioma, then by treating the occlusion when it threatens the visual axis one can prevent amblyopia. All children should have an eye exam between the ages of three and five. Most eye-care professionals use special techniques when dealing with young patients who are unable to communicate.

Questions to Ask Your Doctor

  • How severe is my child’s amblyopia?
  • Which treatment options would best help my child?
  • In addition to the common ones, which symptoms should I watch for?
  • What are the chances my other children will develop this condition?
  • Which type of amblyopia does my child have?
  • Which kinds of tests can we expect during the diagnosis?
  • What are the side effects of the available treatment options?

Did you know: Prevent Blindness America says that only 21 percent of American children have their vision screened before kindergarten, with only 14 percent receiving a comprehensive eye exam?

References:
  • J. Weizer, MD; J Stein, MD, MS “Reader’s Digest Guide to Eye Care” (Quantum Publishing, 2009) 24, 75-76
  • J. Lavine, MD “The Eye Care Sourcebook” (Contemporary Books, 2001) 109, 111-112
  • J. DiGirolamo “The Big Book of Family Eye Care” (Basic Health Publications, 2011) 102-104
  • American Optometric Association, Amblyopia (Lazy Eye) http://www.aoa.org/x4699.xml
This article was last updated on 09/2014