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Amblyopia ("lazy eye")
Amblyopia is reduced best-corrected visual acuity from abnormal visual input during the critical period of visual development, without a structural disease that explains it; it is treated by correcting the refraction and then forcing the weak eye to work — a patch or atropine to the good eye — and the earlier treatment starts the better the outcome.
Why it matters in the exam
The exam asks about causes and treatment. Three causes: strabismus (strabismic) — the brain suppresses the deviating eye; a refractive difference between the eyes (anisometropic) — mainly hyperopia or astigmatism in one eye, so no strabismus and no external sign; and deprivation — congenital cataract, a ptosis covering the pupil or a corneal scar — the most severe and most urgent. High refractive error in both eyes (isoametropic) also causes bilateral amblyopia. The practical definition: a difference of 2 lines or more between the eyes.
The PEDIG studies changed treatment: first glasses alone for several weeks to months — some children improve with them alone; in moderate amblyopia 2 hours of patching a day work as well as 6 hours, and in severe amblyopia 6 hours work as well as full-time patching; atropine 1% to the good eye, even on weekends only, works as well as patching in moderate amblyopia. Children aged 7–12 still respond, and adolescents not treated before may respond. After treatment stops about a quarter of children decline again within a year, so treatment is tapered.
Screening: red reflex test in the newborn and at every infant visit; photoscreening from age one; visual acuity testing at age 3–5. Deprivation amblyopia is a paediatric emergency — a unilateral congenital cataract is operated on in the first weeks of life. Digital binocular treatments are approved as an add-on, not a substitute. The good eye needs follow-up — atropine and patching can cause reverse amblyopia.
Key points
- Reduced corrected acuity from abnormal visual input, without structural disease.
- Causes: strabismus, anisometropia, deprivation.
- Glasses first, then patch or atropine.
- 2 hours of patching equals 6 in moderate amblyopia.
- Deprivation → urgent removal of the obstruction.
Summary table
| Type | Cause | Sign | Treatment |
|---|---|---|---|
| Strabismic | Strabismus | Deviating eye, preferred fixation | Glasses, patch, then alignment |
| Anisometropic | Refractive difference | No external sign | Glasses, then patch or atropine |
| Deprivation | Cataract, ptosis, scar | Absent or blocked red reflex | Urgent removal of the obstruction, then patch |
| Isoametropic | High refraction in both eyes | Bilateral reduction | Full glasses |
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Sources
- AAO Preferred Practice Pattern: Amblyopia, 2022 — Diagnosis and treatment
- Pediatric Eye Disease Investigator Group (PEDIG) amblyopia treatment studies, 2002-2010 — Patching and atropine regimens
- AAO Basic and Clinical Science Course, Section 6: Pediatric Ophthalmology and Strabismus, 2024-2025 — Amblyopia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.