Amblyopia

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 3 Aug 2025

Last updated: 07 Sep 2023

Amblyopia is a visual impairment resulting from abnormal visual stimulation during early childhood, the prevalence of which ranges from 1% to 4%.

Can result from strabismus, form deprivation (e.g., due to congenital cataracts or corneal opacities), and various types of refractive errors. These errors include anisometropia (unequal refractive error between the two eyes), isoametropia (high but similar refractive error in the two eyes), and high astigmatism in one or both eyes.

Amblyopia due to strabismus with or without refractive error is commonly treated with initial optical correction, and subsequent patching or atropine penalization of the better-seeing eye. Amblyopia due to refractive error alone frequently responds to optical correction alone.

Amblyopia due to form deprivation is treated initially with early surgery, to remove the visual obstruction. In unilateral or asymmetric cases, patching of the better-seeing eye is necessary after surgery.

Treatment is highly successful when instituted during the infantile and preschool years, although some children as old as 13-17 years respond to treatment, particularly if there has been no prior therapy.

Definition

Amblyopia is a reduction of best corrected visual acuity (usually unilateral, but may be bilateral) that is not attributable solely to a structural abnormality of the eye or visual pathways.[1] For the brain to learn to see with each eye, and to develop the capacity for binocular vision, each eye must have a clear and focused retinal image, and the two eyes must be aligned. Research has demonstrated that there are critical periods for the development of normal vision, and that amblyopia is associated with structural changes in the primary visual cortex.[2][3]

History and exam

Key diagnostic factors

infant not tracking parent's face
abnormal red reflex

Full details

Other diagnostic factors

asymptomatic
subnormal visual acuity for age in one or both eyes
asymmetric corneal light reflex
unequal behavioral response to alternate eye occlusion
abnormal cover/uncover testing
blurred vision
eye strain
congenital nystagmus
abnormal pupil exam
abnormal external eye exam

Full details

Risk factors

age <9 years
strabismus (misalignment of the eyes)
opacity in the cornea, anterior chamber, lens, vitreous, or retinal surface
severe ptosis or prolonged occlusion of one or both eyes
prematurity
family history of amblyopia or strabismus
hyperopic anisometropia (farsightedness with unequal refractive error between the 2 eyes) of >+1.50 diopter
myopic anisometropia
astigmatism (cylindrical, rather than spherical, defocus of the eye) >2.00 diopter
hyperopia >+4.50 diopter
myopia >-3.00 diopter
developmental delay

Full details

Diagnostic tests

1st tests to order

visual acuity tests (by specialist)
stereopsis (perception of depth or 3-dimensionality) and binocular vision testing
assessment of fixation, ocular alignment and ocular motility
anterior segment exam using a slit lamp
dilated fundoscopy
cycloplegic retinoscopy
binocular red reflex test (Brückner test)

Full details

Emerging tests

visual evoked potentials

Treatment algorithm

ONGOING

without form-deprivation amblyopia

form-deprivation amblyopia

refractory amblyopia

Contributors

Authors

Irene Gottlob, MD

Professor of Ophthalmology

Department of Neuroscience, Psychology and Behaviour

University of Leicester

Ulverscroft Eye Unit

Leicester Royal Infirmary

Disclosures

IG declares that she has no competing interests. IG is an author of references cited in this topic.

Gail Maconachie, PhD, BMedSci

Lecturer

School of Allied Health Professions, Nursing and Midwifery,

Faculty of Health

University of Sheffield

Disclosures

GM declares that she has no competing interests. GM is an author of a reference cited in this topic.

Eleni Papageorgiou, MD, PhD

Consultant in Pediatric Ophthalmology, Strabismus and Neuro-Ophthalmology

Department of Ophthalmology

University Hospital of Larissa

Larissa

Greece

Disclosures

EP declares that she has no competing interests.

Acknowledgements

Dr Irene Gottlob, Dr Gail Maconachie, and Dr Eleni Papageorgiou would like to gratefully acknowledge Dr Tina Rutar, the previous contributor to this topic.

Disclosures

TR declared that she had no competing interests.

Peer reviewers

David Robbins Tien, MD

Associate Clinical Professor of Ophthalmology

Alpert Medical School of Brown University

Director of Ophthalmology

Hasbro Children's Hospital

Providence

Disclosures

DRT declares that he has no competing interests.

David K. Wallace, MD, MPH

Associate Professor of Ophthalmology and Pediatrics

Duke Eye Center

Durham

Disclosures

DKW has received NEI grants of more than 6 figures USD. DKW is an author of a number of references cited in this topic.

Michael Clarke, FRCS, FCOphth

Reader in Ophthalmology

Newcastle University

Newcastle

Disclosures

MC has received NHS research grants of more than 6 figures USD. MC is an author of a number of references cited in this topic.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Cruz OA, Repka MX, Hercinovic A, et al. Amblyopia preferred practice pattern. Ophthalmology. 2023 Mar;130(3):P136-78.Full text Abstract

Hutchinson AK, Morse CL, Hercinovic A, et al. Pediatric eye evaluations preferred practice pattern. Ophthalmology. 2023 Mar;130(3):P222-70.Full text Abstract

US Preventive Services Task Force; Grossman DC, Curry SJ, Owens DK, et al. Vision screening in children ages 6 months to 5 years: US Preventive Services Task Force Recommendation Statement. JAMA. 2017 Sep 5;318(9):836-44.Full text Abstract

American Academy of Ophthalmology. Pediatric ophthalmology/strabismus summary benchmarks - 2022. December 2022 [internet publication].Full text

Wallace DK, Lazar EL, Holmes JM, et al; Pediatric Eye Disease Investigator Group. A randomized trial of increasing patching for amblyopia. Ophthalmology. 2013 Nov;120(11):2270-7.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Refractive error with no amblyopia
- Functional visual impairment
- Central nervous system pathology affecting visual pathways
More Differentials
Guidelines
- Vision rehabilitation preferred practice pattern
- Vision screening for infants and children
More Guidelines
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Amblyopia

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Emerging tests

Treatment algorithm

without form-deprivation amblyopia

form-deprivation amblyopia

refractory amblyopia

Contributors

Authors

Irene Gottlob, MD

Disclosures

Gail Maconachie, PhD, BMedSci

Disclosures

Eleni Papageorgiou, MD, PhD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

David Robbins Tien, MD

Disclosures

David K. Wallace, MD, MPH

Disclosures

Michael Clarke, FRCS, FCOphth

Disclosures

Peer reviewer acknowledgements

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice