Squint in children
Exam Tips
- In OSCEs, classify squint systematically: onset, constancy, direction, tropia/phoria, comitant vs incomitant, accommodative vs non-accommodative, unilateral vs alternating.
- Any acute-onset incomitant squint, restricted eye movements, headache/vomiting, papilloedema, or neurological signs is an urgent same-day ophthalmology/paediatric-neurology pathway.
- Always state that treatment goals are threefold: preserve vision (treat amblyopia), align eyes, and optimize binocular function/quality of life.
- Hypermetropia + esotropia in a toddler strongly suggests accommodative esotropia; cycloplegic refraction is pivotal.
- Pseudostrabismus does not need treatment, but follow-up is sensible because children with pseudostrabismus have higher later strabismus rates.
- Image anchor for revision: review a standard cover-test sequence and Hirschberg reflex diagram in a paediatric ophthalmology atlas when practicing station technique.
Definition
Childhood squint (strabismus) is a persistent or intermittent misalignment of the visual axes, so the two eyes are not directed at the same target simultaneously. The deviation may be inward, outward, vertical, or torsional, and can be manifest (tropia) or latent (phoria); this must be distinguished from pseudostrabismus, where facial anatomy creates a false appearance of eye misalignment.
Pathophysiology
Normal binocular vision requires precise motor alignment of both eyes and cortical sensory fusion. In strabismus, imbalance of vergence control, accommodative drive (especially in hypermetropia), or extra-ocular muscle/innervation function causes discordant retinal images. During visual cortical development, the brain suppresses input from the deviating eye to avoid diplopia/confusion, which can lead to amblyopia and poor stereopsis if untreated in the early childhood critical period. Comitant squints usually reflect non-paralytic binocular control failure, while incomitant patterns suggest neuromuscular or neurological pathology (for example cranial nerve palsy).
Risk Factors
- Hypermetropia (especially linked to accommodative esotropia)
- Anisometropia
- Family history of strabismus (strong hereditary contribution, particularly accommodative forms)
- Low birth weight (major independent risk in premature infants)
- Prematurity
- Maternal smoking during pregnancy
- Neurodevelopmental conditions (for example cerebral palsy, Down syndrome)
- Previous diagnosis of pseudostrabismus
- Assisted delivery (forceps or caesarean section; association reported)
Clinical Features
Symptoms
- Parent/carer notices one eye turning in, out, up, or down
- Intermittent deviation, often worse with fatigue, illness, near work, or bright sunlight (classically intermittent distance exotropia)
- Older child may report intermittent diplopia or blurred vision
- Reduced depth perception/clumsiness due to impaired stereopsis
- Asthenopia (eyestrain) or difficulty sustaining near tasks
- Psychosocial distress, poor confidence, or school/social difficulties
Signs
- Abnormal corneal light reflex and positive cover/uncover or alternate cover test
- Comitant deviation in most common childhood squints; incomitance with gaze-dependent angle is a red flag
- Reduced visual acuity in one eye consistent with amblyopia
- Abnormal head posture (face turn, chin up/down, head tilt) to maintain single vision
- Cross-fixation in infantile esotropia
- Associated nystagmus in some congenital/infantile cases
- Features suggesting pseudostrabismus (for example prominent epicanthic folds) with otherwise normal alignment testing
Investigations
Management
Lifestyle Modifications
- Early referral to orthoptics/paediatric ophthalmology; treatment delay increases risk of permanent amblyopia
- Optimize spectacle adherence for refractive correction (first-line in accommodative esotropia)
- Amblyopia therapy adherence support (patching schedule, school/daytime planning, parental counselling)
- Safety-net advice: urgent reassessment for acute painful squint, neurological symptoms, leukocoria, or rapidly progressive deviation
Pharmacological Treatment
Antimuscarinic penalization for amblyopia (specialist-led)
- Atropine sulfate 1% eye drops: 1 drop to the better-seeing eye once daily on prescribed days (commonly weekend or daily regimens individualized by paediatric ophthalmology)
Used as penalization therapy when indicated for amblyopia associated with squint; usually off-label and protocol-driven. Contraindications/cautions: hypersensitivity to atropine, risk of angle-closure glaucoma, and higher anticholinergic adverse-effect susceptibility in children with neurological impairment. Counsel on photophobia/blurred near vision, avoid overdose, and seek urgent review for systemic toxicity (flushing, fever, tachycardia, confusion).
Surgical / Interventional
- Strabismus muscle surgery (for example bilateral medial rectus recession for esotropia; lateral rectus recession/resection strategies for exotropia) when optical/orthoptic treatment is insufficient
- Surgery for partially accommodative esotropia residual angle after full refractive correction
- Botulinum toxin injection to selected extra-ocular muscles in specific cases under specialist care
- Continue amblyopia and refractive management before/after surgery, as alignment surgery alone does not treat amblyopia
Complications
- Amblyopia (potentially irreversible if not treated early)
- Loss or failure of binocular vision development
- Reduced stereopsis/depth perception
- Compensatory abnormal head posture
- Poor eye contact and communication impact in pre-verbal children
- Psychological and social morbidity (stigma, low self-esteem, anxiety/depressive symptoms)
- Educational and quality-of-life impairment
Prognosis
A squint persisting beyond early infancy is unlikely to self-correct without treatment, and esotropia commonly worsens over time with increasing amblyopia risk. Prognosis is generally good with early, coordinated orthoptic and ophthalmology care, particularly when refractive errors and amblyopia are treated promptly. Later realignment can still provide cosmetic and psychosocial benefit, but recovery of stereopsis/binocular function is less likely in long-standing cases.
Sources & References
🏥BMJ Best Practice(1)
✅NICE Guidelines(1)
- Squint in children[overview]