What is lazy eye?
Lazy eye, or amblyopia, is reduced vision in an eye that is otherwise healthy, caused by the visual system not developing normally in early childhood. It is treated more effectively the earlier it is found.
- Subject
- Children's eyes
- Topic
- Glasses, squints & lazy eye
- Kind of question
- What is…
- Last reviewed
- 22 September 2026
In more detail
This is the main reason screening in early childhood exists. Once the visual system has matured, the same treatment is much less effective.
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Where this answer sits
It is one of 483 answers in the vision and eye health knowledge base, filed under Children's eye health in Glasses, squints & lazy eye . The subject page carries the answers either side of it, and the hub is searchable.
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
General answers cannot tell you what is happening in your own eyes. Only an examination by a qualified ophthalmologist can do that.
Sources & further reading
We prefer primary sources. Where a claim comes from a manufacturer, a single study or a regulator, it is labelled as such below.
- Eye Health Information
Condition-by-condition eye health information from a US government research institute, written for patients rather than for clinicians.
Used for Plain-language explanations of eye conditions and their symptoms; Healthy vision and screening guidance.
Link checked 23 September 2026
- EyeSmart: eye health information for the public
Patient-facing material from the largest ophthalmology professional body, covering conditions, tests and treatments outside refractive surgery.
Used for Cross-checking patient-facing explanations of non-refractive eye conditions; Describing what tests such as dilation and OCT involve.
Link checked 23 September 2026