Strabismus Flashcards
What action does the superior rectus have?
elevates, adducts, medially rotates
What action does the inferior rectus have?
depresses, adducts, excyclotort (laterally rotate)
What does the superior oblique do?
depresses and intorts (medially rotates)
What does the inferior oblique do?
elevates and extorts (laterally rotates)
What muscles does CN 3 innervate?
medial rectus inferior rectus superior rectus inferior oblique levator
Movements of both eyes, conjugate
versions
Disconjugate movements of eyes
vergences
Movements of one eye
ductions
Misalignment of visual axes
strabismus
Latent deviation that appears only when fusion is disrupted
phoria
Manifest deviation, beyond the range of fusional control
tropia
nasalward deviation of the eye, “crossed eye”
esotropia
Temporal deviation of the eye, “walleye”
exotropia
Vertical deviation, relative to higher eye
hypertropia
Angle of deviation remains constant regardless of direction of gaze; range of motion of eyes is full, without limitation or restriction
Most commonly seen in childhood onset strabismus
concomitant strabismus
Angle of strabismus varies with gaze direction; limitation of ocular movements Patient may exhibit abnormal head posture to maintain binocularity
May be congenital or acquired
incomitant strabismus
abnormalities of binocularity, motion processing, poor fusional vergences
comitant
Developmental (Duanes’, Brown’s), Neurologic (cranial nerve palsy, myasthenia), Restrictive (trauma, thyroid disease)
incomitant
What are some ways to diagnose strabismus?
cover test, alternate cover test light reflex testing angle of deviation measured with prisms motility evaluation sensory testing to assess binocularity
common in infants: wide flat nasal bridge and epicanthal folds, normal alignment by light reflex and cover tests
pseudoesotropia
autosomal dominant, inelastic muscles and ptosis, positive forced
ductions
congenital fibrosis syndrome
lymphocytic infiltration and secondary fibrosis of extraocular muscles in thyroid disease
Graves’ disease
scarring/entrapment of orbital tissue/extraocular muscles
orbital fractures
microvascular, tumor, trauma, aneurysm
cranial nerve palsies
eye down and out, ptosis, +/- pupillary involvement
third nerve palsy
oblique diplopia and torsion, bilateral often secondary to trauma
fourth nerve palsy
face turn towards affected side
sixth nerve palsy
variable strabismus and ptosis, Acetylcholine receptor antibodies, Tensilon test
myasthenia gravis
strabismus surgery which weakens effect of operated muscle
recession
strabismus surgery which enhances the effect of operated muscle
resection
strabismus surgery which shifts the force vector of muscle
transposition
