Diplopia, Strabismus & Amblyopia
Distinguish optical doubling from misalignment and understand developmental visual loss.
Quick revision ↓ Medical Dictionary
01Monocular or binocular
Ask whether doubling disappears when either eye is covered. Binocular diplopia resolves with either eye covered and suggests misalignment. Monocular doubling persists when the affected eye views alone and often has an optical cause. The distinction guides assessment but does not establish a diagnosis. Sudden onset, headache, ptosis or other neurological signs increases urgency.
02Alignment and movement
Inspect the corneal light reflex and use cover testing appropriately to identify manifest or latent deviation. Assess movements and whether diplopia changes with gaze. Cranial nerve palsy, restrictive orbital disease and neuromuscular junction disorders are among the causes. New adult strabismus is not simply a cosmetic problem and requires investigation matched to the presentation.
03Childhood visual development
Amblyopia is reduced visual development associated with unequal input, strabismus or deprivation during childhood. Examine for structural causes before assigning the diagnosis. A child may not complain because the better eye compensates. Age-appropriate acuity testing, refraction and eye health assessment are important, and timely treatment offers better opportunities for improving visual development.
04Treatment principles
Correct refractive error and address the underlying cause. Selected children need patching or pharmacological penalisation prescribed and monitored by the eye team. Alignment surgery and amblyopia therapy have different goals; straightening the eyes does not automatically restore acuity. Follow-up checks response and protects the vision of both eyes while supporting adherence and family understanding.
05Urgent exceptions
New squint with headache, vomiting, neurological signs or an abnormal red reflex needs urgent evaluation. A white reflex is not explained safely by amblyopia alone. In adults, acute diplopia with severe headache or a pupil abnormality requires emergency assessment. Advise against driving with uncontrolled diplopia and follow applicable local fitness-to-drive rules.
High-Yield Revision
- Binocular diplopia resolves when either eye is covered.
- Amblyopia requires assessment for structural causes.
- Alignment and visual acuity are separate treatment outcomes.
Common Pitfalls
- Calling every childhood squint cosmetic.
- Prescribing unsupervised patching without a diagnosis.
References & Further Reading
Read the relevant guideline sections alongside these original clinical teaching cases. Local pathways, available services and individual patient factors determine care.
Reference review: 28 September 2026. Consult current local protocols for prescribing, procedures and escalation.