Neurology - Squint Flashcards
What is a squint?
Misalignment of the eyes
AKA strabismus causes double vision
What does a squint lead to in childhood?
Brain reduces signal from less dominant eye
Results in one eye becoming dominant and other eye ignored (lazy eye)
If not treated lazy eye becomes more disconnected from the brain and becomes worse - called amblyopia
What are concomitant squints?
Differences in control of extra-ocular muscles
What are paralytic squints?
Rare
Due to paralysis in one or more extra ocular muscles
What do each of these mean?
Strabismus
Amblyopia
Esotropia
Exotropia
Hypertropia
Hypotropia
Strabismus
Eyes misaligned
Amblyopia
Affected eye becomes passive and has reduced function
Esotropia
Inward squint - towards nose
Exotropia
Outward squint - towards ear
Hypertropia
Upward moving affected eye
Hypotropia
Downward moving affected eye
What causes a squint?
Usually idiopathic
- Hydrocephalus
- CP
- SOL e.g. retinoblastoma
- Trauma
What tests are used on examination for squints?
General inspection
Eye movements
Fundoscopy - rule out retinoblastoma, cataracts
Visual acuity
Hirschberg’s test
Shine pen-torch at 1 metre away
When they look at it, observe reflection of light on cornea
Reflection should be central and symmetrical, deviation indicates a squint
Cover test
Cover one eye and ask patient to focus on object in front of them
Move cover across to opposite eye and watch movement of previously covered eye
If the eye moves inward it means it drifted outwards when covered (exotropia)
If eye moves outwards it means it drifted inwards when covered (esotropia)
How are squints managed?
Until 8 visual fields still developing, so must treat before 8
Delayed treatment increases risk of permanent squint
Coordinated by ophthalmology
Treat any underlying causes
Occulusive patch
Cover good eye and force weaker eye to develop
Atropine drops
Used in good eye causing blurred vision, force bad eye to get better
