Lazy eye (amblyopia) is decreased vision that results from abnormal visual development in infancy and early childhood. Although lazy eye usually affects only one eye, it can affect both eyes. Lazy eye is the leading cause of decreased vision among children. Left untreated, vision loss may range from mild to severe.
With lazy eye, there may not be an obvious abnormality of the eye. Lazy eye develops when nerve pathways between the brain and the eye aren't properly stimulated. As a result, the brain favors one eye, usually due to poor vision in the other eye. The weaker eye tends to wander. Eventually, the brain may ignore the signals received from the weaker — or lazy — eye.
Usually doctors can correct lazy eye with eye patches, eyedrops, and glasses or contact lenses. Sometimes lazy eye requires surgical treatment.
Signs and symptoms of lazy eye include:
- An eye that wanders inward or outward
- Eyes that may not appear to work together
- Poor depth perception
Although lazy eye usually affects just one eye, it's possible for both eyes to be affected. Sometimes lazy eye is not evident without an eye exam.
When to see a doctor
Primary care doctors often check vision as a routine part of well-child checkups — especially if there's a family history of crossed eyes, childhood cataracts or other eye conditions. If you notice your child's eye wandering at any time beyond the first few weeks of life, consult your child's doctor.
Depending on the circumstances, your doctor may refer your child to a specialist in eye conditions (ophthalmologist or optometrist). For all children, a complete eye exam is recommended between ages 3 and 5.
Anything that blurs a child's vision or causes the eyes to cross or turn out may cause lazy eye. There are three common causes of lazy eye:
- Strabismic. The most common cause of lazy eye is strabismus - an imbalance in the muscles responsible for positioning of the eyes. This imbalance can cause the eyes to cross in or turn out. The muscle imbalance prevents the eyes from tracking together in a coordinated way.
- Deprivation. Deprivation lazy eye occurs if there is a problem with one eye, such as a cloudy area in the lens (cataract). This "deprives" the child of clear vision in the eye.
- Refractive. This type of lazy eye is the result of a significant difference between the vision in each eye, due to nearsightedness, farsightedness or an imperfection on the surface of the eye (astigmatism). These are the types of vision problems typically corrected by glasses or contact lenses.
Occasionally, a wandering eye is the first sign of an eye tumor.
Lazy eye tends to run in families. Lazy eye may be more likely among children who are born prematurely or with low birth weight, or who are born in a family with a history of childhood cataracts or serious eye disease.
Left untreated, lazy eye can cause permanent vision loss. In fact, lazy eye is the most common cause of single-eye vision impairment in young and middle-aged adults.
Preparing for your appointment
Your child is most likely to be diagnosed with lazy eye during a vision exam. Every child should have a complete eye exam between ages 3 and 5. If your child is in this age range or has any symptoms of eye or vision problems, make an appointment with your doctor. He or she may refer you to an eye specialist (ophthalmologist or optometrist).
What you can do
To prepare for your appointment:
- Make a note of any other medical issues. Include any other eye problems your child has had.
- Make a list of all medications and dosages your child is taking. Include any prescription and nonprescription drugs, vitamins, or other supplements.
- Write down any allergies. Include medications, food or other substances to which your child may have an allergy.
- Include family history. Tell the doctor about any family history of eye problems, such as lazy eye, cataracts or glaucoma.
- Prepare questions. Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together.
Some basic questions to ask your doctor include:
- Does my child have lazy eye?
- Other than lazy eye, is there any other possible diagnosis?
- If this is lazy eye, what is the likely cause?
- Is lazy eye associated with any other health conditions?
- What treatment options are most likely to help my child?
- How much improvement can we expect with treatment?
- Is my child at risk of other eye-related or non-eye-related complications from this condition?
- Is my child at risk of a recurrence of this condition?
- What treatment options are available if there is a recurrence?
- How often should my child be seen for follow-up visits?
- When would you recommend seeing another specialist, such as a pediatric ophthalmologist?
- Are there any brochures or other printed material that I can take with me? What websites do you recommend?
In addition to questions you've prepared in advance, don't hesitate to ask questions during your appointment anytime you don't understand something.
Tests and diagnosis
Your doctor will diagnose lazy eye with a thorough eye exam. He or she will look for a wandering eye, as well as a difference in vision between the eyes or poor vision in both eyes. Depending on your child's age, tests may include the following:
- Newborns. Red reflex test to look for cataracts, using a lighted magnifying device (ophthalmoscope)
- Infants. Test for ability to fixate their gaze and follow a moving object, as well as check for strabismus
- Toddlers. Red reflex test, photo screening or remote autorefraction
- Preschoolers and older children. Testing using pictures or letters. Each eye is patched in turn to test the other
Your doctor may also check for inflammation, tumors and other inner eye problems.
Treatments and drugs
Ideally, lazy eye treatment begins in early childhood — when the complicated connections between the eye and the brain are forming. Depending on the cause and the degree to which your child's vision is affected, treatment options may include:
- Corrective eyewear. If a condition such as nearsightedness, farsightedness or astigmatism is contributing to lazy eye, your doctor will likely prescribe corrective glasses or contact lenses. Sometimes corrective eyewear is all that's needed.
- Eye patches. To stimulate the weaker eye, your child may wear an eye patch over the stronger eye. Most children older than age 4 will benefit from wearing the patch three to six hours a day. This helps the part of the brain that manages vision to develop more completely.
- Eyedrops. A daily or twice-weekly drop of a drug called atropine can temporarily blur vision in the stronger eye. This will encourage your child to use his or her weaker eye, and offers an alternative to wearing a patch. Drops may not work as well when the stronger eye is nearsighted.
- Surgery. If your child's eyes cross or wander apart, your doctor may recommend surgical repair for the eye muscles. Your child may also need surgery if he or she has droopy eyelids or cataracts.
For some children, glasses or contact lenses alone will improve lazy eye, but other children also need to use a patch or eyedrops. Patches and eyedrops appear to work equally well except when the stronger eye is nearsighted.
A number of "active" treatments such as drawing, puzzles or computer games — sometimes in addition to patching or eyedrops — are now available. However, good evidence does not yet exist for their effectiveness compared with "passive" treatments such as eyedrops and patching.
For most children with lazy eye, proper treatment improves vision within weeks to several months — and the earlier the treatment is started, the better. Although research suggests that the treatment window extends through the teenage years, results are better when treatment begins in early childhood.