Eye health resource
What Is Amblyopia?
Amblyopia, often called lazy eye, is reduced vision caused by abnormal visual development in childhood. Learn how unequal prescriptions, strabismus, or blocked visual input can cause it and how glasses, patching, atropine, or specialist treatment may help.
Reviewed for accuracy by Justin Bazan, OD on .
Amblyopia is reduced vision caused by abnormal visual development during childhood. It is often called “lazy eye,” although the eye is not lazy and the child cannot control the problem. Amblyopia usually affects one eye but can sometimes affect both.
The developing brain needs a clear, appropriately aligned image from each eye. When one eye consistently provides a poorer or conflicting image, the brain may rely more heavily on the other eye and normal visual development can be interrupted.
What Causes Amblyopia?
Common mechanisms include:
Unequal or Uncorrected Refractive Error
If one eye is much more farsighted, nearsighted, or astigmatic than the other, the brain may receive a clearer image from one eye and a blurrier image from the other. This is often called refractive or anisometropic amblyopia.
Amblyopia can also affect both eyes when a significant prescription is present in both eyes and remains uncorrected during visual development.
Strabismus
When the eyes point in different directions, the brain may suppress the image from one eye to avoid double vision or visual confusion. That can lead to strabismic amblyopia.
Strabismus and amblyopia are related but different: strabismus is an alignment problem; amblyopia is reduced vision from abnormal development.
Visual Deprivation
Anything that significantly blocks a clear image early in life can cause deprivation amblyopia. Examples include a congenital cataract, severe drooping eyelid that blocks the visual axis, or certain corneal problems.
Deprivation amblyopia can be especially time-sensitive because the underlying obstruction may need prompt treatment.
What Are the Signs of Amblyopia?
Amblyopia is often hard for parents to detect because the child may see well with the better eye and assume that their vision is normal.
Possible clues include:
- an eye that turns or drifts;
- closing one eye;
- unusual head position;
- poor depth perception;
- a failed vision screening; or
- a large prescription difference discovered during an eye exam.
Many children have no obvious outward sign at all.
How Is Amblyopia Diagnosed?
Diagnosis requires measuring vision as reliably as possible for the child's age, checking the prescription in each eye, assessing alignment and eye movements, and examining eye health to identify anything that could be limiting visual input.
Children do not have to know letters. Pictures, symbols, objective measurements, and age-appropriate testing can provide useful information even in young children.
How Is Amblyopia Treated?
The first step is to address the cause of the blurred or abnormal visual input. That may mean prescribing the correct glasses or contact lenses, treating a cataract or other structural obstruction, or managing strabismus.
If amblyopia remains, treatment may include:
- Patching the better-seeing eye for a prescribed amount of time so the brain uses the amblyopic eye more.
- Atropine penalization in selected cases, using drops in the better-seeing eye to temporarily reduce its near focusing advantage and encourage use of the amblyopic eye.
The dose and schedule are individualized. More patching is not automatically better, and atropine should be used only under appropriate clinical supervision.
Why Does Early Treatment Matter?
Visual development is most adaptable in childhood, so earlier identification and treatment generally offer the best chance of improvement. Older children can still respond to treatment in some situations, so a child should not be denied evaluation simply because the problem was discovered later than ideal.
Untreated amblyopia can leave a permanent difference in vision between the eyes.
How Often Should Children Be Checked?
Vision screening is important and helps identify many children who need further evaluation. For low-risk children, current American Optometric Association guidance also recommends a comprehensive eye assessment between 6 and 12 months, at least one exam between ages 3 and 5, and an exam before first grade with annual examinations thereafter.
Park Slope Eye participates in InfantSEE, and qualifying InfantSEE assessments are available at no charge during the first year of life.
Amblyopia Care at Park Slope Eye
Park Slope Eye optometrists can identify amblyopia risk, evaluate refractive error and alignment, prescribe appropriate optical correction, and monitor selected cases. Children who need pediatric ophthalmology, surgery, or specialist treatment outside our current scope are referred appropriately.
Park Slope Eye does not currently provide Vision Therapy.
If you are concerned that your child's eyes see differently or they have failed a screening, learn more about pediatric eye care or book an appointment.
Originally published . Substantially updated .