Ophthalmic condition in which the eyes do not properly align with each other when focusing to look at an object (i.e. poor fusion)

Aetiology

• Commonly onset is in childhood, can start in adulthood but this is less common
• Can occur due to muscle dysfunction, farsightedness, problems in the brain, trauma or infections
• Risk factors include premature birth, cerebral palsy and a family history of the condition

Clinical features

Symptoms

• Misalignment of the eyes
• Reduced visual acuity
• Diplopia
• Asthenopia (i.e. eye strain, fatigue or pain), particularly in the afternoon or at the end of the day

Signs

• Corneal reflections will be asymmetrical

Investigations

• Cover test: the direction of movement tells you which type
  • Outward movement of eye → esotropia
  • Inward movement of eye → exotropia
  • Downward movement of eye → hypertropia
  • Upward movement of eye → hypotropia

Management

• Treatment depends on type of strabismus and the underlying cause; may include the use of glasses and possibly surgery