Last reviewed: 1 Sep 2023
Last updated: 07 Sep 2023



History and exam

Key diagnostic factors

  • infant not tracking parent's face
  • abnormal red reflex
More key diagnostic factors

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
Other diagnostic factors

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
More risk factors

Diagnostic investigations

1st investigations 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)
More 1st investigations to order

Emerging tests

  • visual evoked potentials

Treatment algorithm


without form-deprivation amblyopia

form-deprivation amblyopia

refractory amblyopia



Irene Gottlob, MD

Professor of Ophthalmology

Department of Neuroscience, Psychology and Behaviour

University of Leicester

Ulverscroft Eye Unit

Leicester Royal Infirmary



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

Gail Maconachie, PhD, BMedSci


School of Allied Health Professions, Nursing and Midwifery,

Faculty of Health

University of Sheffield



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




EP declares that she has no competing interests.


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


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




DRT declares that he has no competing interests.

David K. Wallace, MD, MPH

Associate Professor of Ophthalmology and Pediatrics

Duke Eye Center




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




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.

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