Types of Amblyopia
and What Causes Each
Lazy eye is one name for several different problems. The type depends on what disrupted the eye's development, and the type shapes the treatment. Answer five questions to see which type fits.
What are the types of amblyopia?
The main types of amblyopia are strabismic (caused by a squint), anisometropic (a large difference in prescription between the eyes), refractive or bilateral (high prescriptions in both eyes), meridional (uncorrected astigmatism) and deprivation (something blocking vision, such as a cataract or droopy eyelid). Many children have a mix of strabismic and anisometropic amblyopia.
- Most common
- Anisometropic and strabismic
- Most urgent
- Deprivation
- Most often missed
- Anisometropic: the eyes look straight
- Affects both eyes
- Refractive (bilateral)
Which Type Fits?
Answer what you know. The matching types light up. Leave a question on Not sure if you do not know.
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Strabismic
An eye turn makes the brain switch that eye off.
Lazy eye treatment, then squint treatment.
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Anisometropic
One eye needs a much stronger prescription.
Full-time glasses first, then patching or drops.
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Mixed
An eye turn and unequal prescriptions together.
A longer course, plus squint treatment.
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Refractive (bilateral)
High, uncorrected power in both eyes.
Full-time glasses and regular reviews.
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Meridional
Uncorrected astigmatism blurs some directions.
Glasses with full astigmatism correction.
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Deprivation
Something blocked the image during development.
Remove the cause quickly, then intensive treatment.
Answer Yes to anything you know. Matching types will light up.
A guide to the terms, not a diagnosis. The type is confirmed by measuring each eye and the prescription.
Anisometropic and Strabismic Amblyopia
Anisometropic amblyopia happens when one eye needs a much stronger prescription than the other. The brain favours the clearer image and the blurred eye never develops full vision. Because the eyes look straight, it is often found late, at a school screening. Glasses alone bring a large improvement in many children.
Strabismic amblyopia develops when one eye turns in, out, up or down. The two eyes send different pictures, and to avoid double vision the brain switches off the turned eye. It needs lazy eye treatment and treatment for the squint; see lazy eye vs squint.
When both are present it is called mixed, or combined-mechanism, amblyopia, and it tends to need a longer course.
How Big Is the Gap?
Choose the line the weaker eye reads. Clinicians grade every type by this same severity band.
Moderate lazy eye
Move the slider to compare the two eyes.
With each eye tested on its own, the gap between them is what defines a lazy eye.
An illustration of blur and suppression, not a vision test. Only an eye examination can measure each eye.
Refractive, Meridional and Deprivation Amblyopia
Refractive (isoametropic) amblyopia affects both eyes when both have high, uncorrected prescriptions, usually long-sightedness or astigmatism. Vision is reduced in both eyes and improves steadily with full-time glasses.
Meridional amblyopia comes from uncorrected astigmatism. Lines in one direction stay blurred during development, so vision stays reduced for those orientations. Early glasses that fully correct the astigmatism are the treatment.
Deprivation amblyopia is the rarest and most urgent. A cataract, a droopy eyelid, a corneal scar or bleeding in the eye blocks the image. The obstacle must be removed quickly, and intensive treatment follows. See form deprivation amblyopia for more.
Not sure which type your child has? An assessment finds the cause, and the cause sets the plan.
How Each Type of Amblyopia Is Treated
| Type | Cause | First step | Then |
|---|---|---|---|
| Anisometropic | Unequal prescriptions | Full-time glasses | Patching or drops, binocular therapy |
| Strabismic | An eye turn | Glasses where needed | Patching or drops, then squint treatment |
| Mixed | Both of the above | Full-time glasses | A longer course, plus squint treatment |
| Refractive | High power in both eyes | Full-time glasses | Regular reviews |
| Meridional | Astigmatism | Glasses with full correction | Regular reviews |
| Deprivation | A blocked image | Remove the cause quickly | Intensive patching and close follow-up |
Whatever the type, treatment that trains both eyes together, such as dichoptic therapy, helps reduce suppression and build depth perception. The age at which treatment starts matters for every type; see the lazy eye treatment age limit.
Everything We Have Written on Lazy Eye
Back to the overview: amblyopia (lazy eye) treatmentBy age
Treatments
Common questions
- Types of amblyopia
- Lazy eye vs squint
- Is lazy eye curable?
- Deprivation amblyopia
Parent Guides on This Topic
- Spotting lazy eye in a baby The age-by-age warning signs from newborn to three years, and why a school screening will not find them.
- Can lazy eye actually be cured? What the success rates look like by age, and why binocular therapy outperforms patching alone.
- Patching versus vision therapy Why amblyopia often returns after patching stops, and what treating the suppression instead involves.
- Lazy eye treatment, step by step Glasses, patching, drops and binocular therapy in the order they are used, with a tool to see which fit your child.
Questions Families Ask
What is anisometropic amblyopia?
What is the most common type of amblyopia?
What is meridional amblyopia?
Which type of amblyopia is hardest to treat?
Can amblyopia affect both eyes?
Find Out How Much the Weaker Eye Can Gain
A lazy eye assessment measures the vision in each eye, checks for a squint and for suppression, and sets out a written plan. In clinic in Chennai and Hyderabad, with online consultations across India.