Strabismus

Question 1

What is the function of the medial rectus?

Answer 1

it adducts the eye

Question 2

What is the function of the lateral rectus?

Answer 2

it abducts the eye

Question 3

What are the functions of the superior rectus muscle?

Answer 3

it primarily elevates the eye

it also adducts & intorts the eye

Question 4

What are the functions of the inferior rectus muscle?

Answer 4

it depresses, adducts, and excyclotorts the eye

Question 5

What is the function of the superior oblique muscle?

Answer 5

depresses & intorts the eye

Question 6

What is the function of the inferior oblique muscle?

Answer 6

elevates & extorts the eye

Question 7

Which extra ocular muscles are innervated by the 3rd CN?

Answer 7

medial rectus
inferior rectus
superior rectus
inferior oblique 
levator palpebra

Question 8

Which extra ocular muscles are innervated by the 4th CN?

Answer 8

innervates the superior oblique

Think SO4

Question 9

Which extra ocular muscles are innervated by the 6th CN?

Answer 9

lateral rectus

Question 10

What are ductions?

Answer 10

movements of one eye

Question 11

What are versions?

Answer 11

movements of both eyes in the same direction (conjugate)

Question 12

What are vergences?

Answer 12

movements of both eyes in a disconjugate way (not same direction)

Question 13

What is strabismus?

Answer 13

misalignment of visual axes

Question 14

What is phoria?

Answer 14

latent deviation of eyes

**appears only when fusion disrupted

Question 15

What is tropia?

Answer 15

manifest deviation

**beyond the range of fusional control

Question 16

What is esotropia?

Answer 16

nasalward deviation of an eye (cross eye)

Question 17

What is exotropia?

Answer 17

temporal deviation “wall eye”

Question 18

What is hypertropia?

Answer 18

vertical deviation, relative to higher eye

Question 19

What is concomitant strabismus?

Answer 19

• *this is where the angle of deviation remains constant regardless of the direction of gaze
• *range of motion of eyes is full-without limitations

Question 20

What is incomitant strabismus?

Answer 20

• *this is where the angle of deviation varies with the direction of the gaze
• *ocular movements are limited
• *pt may have head in an abnormal posture to maintain binocularity…

Question 21

Which type of strabismus is more commonly seen in childhood onset strabismus?

Answer 21

concomitant strabismus more common

Question 22

Is incomitant strabismus congenital?

Answer 22

it can be…or it can be acquired.

Question 23

In which type of strabismus do you esp see abnormalities of binocularity, motion processing, poor fusional vergences?

Answer 23

comitant strabismus

Question 24

Which type of developmental diseases can lead to incomitant strabismus?

Answer 24

Duane’s
Brown’s
mobius

Question 25

Which type of neurologic diseases can lead to incomitant strabismus?

Answer 25

cranial nerve palsy | myasthenia

Question 26

Which type of restrictive diseases can lead to incomitant strabismus?

Answer 26

orbital fractures-trauma grave's disease-thyroid disease congenital fibrosis syndrome

Question 27

What are some important tests to do when diagnosing strabismus?

Answer 27

``` cover test, alternate cover test light reflex testing angle of deviation measured with prisms motility evaluation for ductions & versions sensory testing to assess binocularity ```

Question 28

What is pseudoesotropia? Which category does this fall into? Which age group is this common in? What are some of its other characteristics?

Answer 28

this is where the eyes appear to be crossed, but really they are straight & properly aligned **characteristics: wide flat nasal bridge, epicanthal folds **common in infants Category: comitant strabismus

Question 29

How does pseudoesotropia do with light reflex & cover tests?

Answer 29

all is normal with these tests, b/c there really isn't a problem, just large epicanthal folds.

Question 30

What is congenital esotropia?

Answer 30

this is a congenital condition in which the eyes are turned inward there is a large angle deviation, cross fixation, and limitation of abduction

Question 31

Congenital esotropia is often confused with which condition? What is the treatment? Which category does it fall into?

Answer 31

confused with congenital sixth nerve palsy requires surgical treatment falls into the category of comitant strabismus

Question 32

What is accommodative esotropia? Which category does it fall into? What is the usual age of onset?

Answer 32

this is where the eyes are deviated inwardly somewhat, but really only b/c the kid is trying to focus--over-convergence related to accommodation in hyperopia * *usual onset: 2-3 years * *comitant strabismus

Question 33

What is the treatment for accommodative esotropia?

Answer 33

glasses | bifocals are sometimes necessary

Question 34

What is exotropia? Which category does this belong to? Which age group does this affect?

Answer 34

eyes deviate outward when fatigued or not paying attention normal binocular vision when eyes are straight seen intermittently in childhood belong to comitant strabismus category

Question 35

What is Duane's Retraction Syndrome? Which category does this fall into?

Answer 35

absence of 6th nerve nucleus--deficient abduction miswiring of 3rd nerve--cocontraction of medial & lateral rectus. **gives globe retraction on adduction Category: Incomitant Strabismus, developmental

Question 36

What is mobius syndrome? Which category does it fall into?

Answer 36

congenital bilateral 6th & 7th nerve palsies. | Category: Incomitant Strabismus, developmental

Question 37

What is Brown's syndrome? Is it congenital? Which category does it belong to?

Answer 37

abnormality of a trochlear pulley--superior oblique problems deficit of elevation of eye in adduction **can be congenital or acquired **Incomitant Strabismus, Developmental

Question 38

What is congenital fibrosis syndrome? How is it inherited? What is its category?

Answer 38

w/ this syndrome you have inelastic muscles & ptosis get positive forced ductions autosomal dominant disorder Incomitant Strabismus, Restrictive

Question 39

How does Graves' disease lead to eye problems? Which category does it fall into?

Answer 39

you get lymphocyte infiltration & secondary fibrosis of the extra ocular muscles Category: Incomitant Strabismus, Restrictive

Question 40

What's the deal with orbital fractures? Which category does this fit into?

Answer 40

this causes scarring or entrapment of orbital tissues & extra ocular muscles... Category: Incomitant Strabismus, Restrictive

Question 41

What are some things that can cause cranial nerve palsies & neurological incomitant strabismus?

Answer 41

microvascular problems a tumor trauma aneurysm

Question 42

What is the specific effects seen in 3rd nerve palsy?

Answer 42

the eye moves down & out you get droopy eyelid (ptosis) sometimes have pupillary involvement

Question 43

What are the specific effects seen in 4th nerve palsy?

Answer 43

oblique diplopia & torsion | this is seen bilaterally, usu following trauma

Question 44

What are the specific effects seen in 6th nerve palsy?

Answer 44

difficulty with abduction of eyes | face turns towards the affected side

Question 45

What's the deal with myasthenia gravis? Which category does this fall into?

Answer 45

this is a problem involving acetylcholine receptor antibodies you get variable strabismus & ptosis can use the tensilon test Category: Neurological Incomitant Strabismus

Question 46

When you do recession in strabismus surgery...what happens to the eye you operate on?

Answer 46

it weakens the effect of this operated muscle

Question 47

When you do resection in strabismus surgery...what happens to the eye you operate on?

Answer 47

this enhances the effect of the operated muscle

Question 48

When transposition happens in strabismus surgery...what is the result?

Answer 48

this shifts the force vector of the muscle

Question 49

What happens in normal single binocular vision? What is steropsis?

Answer 49

there is a fusion of images from both eyes | if you get sufficient fusion you get stereopsis & you can have depth perception.