Diplopia Flashcards
How does monocular diplopia resolve?
With pinhole
If you cover one eye and the diplopia resolves…
Binocular diplopia -
1) Innervational misalignment
2) Mechanical misalignment
When do you see the maximum separation of images?
Position of gaze where the muscle is the weakest or most restricted. (left 6th N palsy, worse in left gaze)
CN4 palsy - head tilt
RIGHT 4 - head tilts to LEFT
LEFT 4 - head tilts to RIGHT
What conditions mimic blepharoptosis (eye lid ptosis)
- Hypotropia (lookin down close other eye, will look up)
- contralateral lid retraction seen in graves disease
- Dermatochalasis - loose skin
- Brow ptosis seen in bell’s palsy
What causes true ptosis
- congenital
- CN3
- Horners
- Myesthenia gravis
symmetric misalignment in all positions of gaze is called
Comitant
Childhood strabismus
Chronic innervational disease
Asymmetric mislignment greatest in position of most affected muscle
Incomitant
Innervational or
Mechanical
Examples of mechanical causes of incomitant binocular diplopia
Orbital fracture
Graves disease
Examples of innervation causes of incomitant binocular diplopia
- Stroke, brainstem
- cn 3,4, 6 PALSY
- internuclear opthalmoplegia
- myesthenia gravis
Graves disease - what happens
Accumulation of glucosaminoglycans in INFERIOR RECTUS and MEDIAL rectus - become thickened and pull eye down or in
Acquired conditions of cranial nerve palsies
- Ischemia
- tumor
- Demylination
- Trauma
- metabolic - thymine deficiency
- Myesthenia gravis
What is myesthenia gravis
Antibodies to Nicotinic acetylcholin receptors
- fatiguability -
IMITATOR - PUPIL NOT INVOLVED!!
What do you see in a patient with a 6th nerve palsy
- Esodeviation (eye is in)
- Horizontal diplopia
- Ischemia (hypertension/diabetes)
EXCLUDE INCREASE ICP. PAPILLEDEMA
6th nerve palsy can be a….
FALSE localizing sign -
it is subject to compression
e.g. subcranial hemorrhage
Features of CN4 palsy
- hYPERtropia - affected eye - look up
- Head tilts to opposite side
- Positive 3 step test?
- Vertical/diagonal diplopia
Causes of CN4 palsy
- TRAUMA most common
- Congenital
- Ischemia (diabetes hypertension)
- RARELY TUMORS OR ANEURYSM
when you tilt your head to the right
Right eye INCYCLOTORTS
Left eye excyclotorts
3 step test for SO - straight ahead gaze, lateral gaze
- Straight ahead, bad eye hypertropes
- Lateral gaze (OPPOSITE to affected eye) WORSE - unaffected inferior oblique - hypertrope
- Head tilt to affected side - overactive superior rectus - worse
When is the pupil spared in 3rd nerve palsy
Likely MICROVASCULAR ischemia - central
If pupil is involved - THINK PCOM -
Aneurysm of the pcom is like a
3rd nerve pupil bomb
A medial rectus palsy is not necessarily a Partial 3rd nerve palsy! no think of something else
- Internuclear opthalmoplegia
2. Myesthenia gravis
Orbital apex syndrome -
- RAPD if optic nerve is compressed
2. 3,4,6 palsy
A carotid cavernous sinus fistula
can cause 6th cranial nerve palsy
Pituitary apoplexy -
- CN3 palsy - no pupil affected
2. Bitemporal hemianopsia
Which two conditions are least likely to present with loss of vision and binocular diplopia?
- 3rd nerve palsy and pcom aneurysm
2. Myesthenia gravis
Which 3 conditions CAN cause double vision and loss of vision
- OPTIC NEURITIS
- pituitary apoplexy
- Giant cell arteritis
In giant cell arteritis what is high?
platelets
ESR
CRP
In strabismus surgery a recession will
weaken the muscle decrease tension
recess antagonis muscle… less double vision
When do you perform a strabismus surgery
After 12 months
Botox to right lateral rectus if they have 6th nerve palsy
IS not GOOD - botox relaxes the muscle -
make it WORSE - need to weaken the antagonist muscle - like medial rectus
