×
MedSchool: Ace Your OSCEsThe Medical Company
 
 
 
 
 
GET - On the App Store
View
Cranial Nerves
 
Cranial Nerves
 

Strabismus

February 15th, 2021
 
 
 
Bookmark

Overview

Strabismus is misalignment of the eyes, either medially (esotropia) or laterally (exotropia).
Strabismus is often quite subtle and difficult to detect; slight angulation of the head to either side may be a sign of compensation for a subtle strabismus.
  • Causes of Strabismus

  • Structural - intraocular or orbital mass
  • Ocular muscle weakness
  • Trauma
  • Neurological - oculomotor (III), trochlear (IV), abducens (VI) or upper motor neuron lesion
  • Fatigue / stress

Cover Test

The cover test is a useful test for determining the presence of a tropia (constant, or manifest strabismus).
In strabismus, there is a normal eye that tends to fixate on objects, an an affected eye that is deviated slightly outward, inward, upward or downward.
  • How to Perform

  • Ask the patient to look at an object such as the wall in front of them. Cover one eye using a hand or an opaque cover for a few seconds, and look for movement  of the non-covered eye.
  • Cover Test
  • Interpretation

  • Non-covered eye does not move - means that no strabismus is present, or the non-covered eye is the normal eye
  • Non-covered eye moves inward - suggests an exotropia of the non-covered eye (i.e. that it is angulated outward)
  • Non-covered eye moves outward - suggests an esotropia of the non-covered eye (i.e. that it is angulated inward)

Uncover Test

The uncover test is a useful test for determining the presence of a phoria (intermittent, or latent strabismus).
  • How to Perform

  • Ask the patient to look at an object such as the wall in front of them. Cover one eye using a hand or an opaque cover for a few seconds, and then remove it quickly. Look for movement in the now uncovered eye.
  • Uncover Test
  • Interpretation

  • The uncovered eye moves inward - suggests an exophoria (i.e. the covered eye transiently moves outward when covered then corrects inward on uncovering)
  • The uncovered eye moves outward - suggests an esophoria (i.e. the covered eye transiently moves inward when covered then corrects outward on uncovering)
Next Page
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Want more info like this?
  • Your electronic clinical medicine handbook
  • Guides to help pass your exams
  • Tools every medical student needs
  • Quick diagrams to have the answers, fast
  • Quizzes to test your knowledge
Sign Up Now
   
 
 

Snapshot: Initialising...