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

Strabismus

 
 
 
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...