Eye Movement Defects Flashcards
what is the first manifestation of a squint (eyes look in different directions)
diplopia (double vision)
different types of double vision
horizontal
vertical
both
how to diagnose a squint (tropia)
cover test
describe how to carry out a cover test
glasses on
look at corneal reflection (slightly nasal- will be asymmetrical in a manifest squint)
cover one eye and watch the other eye for movement
if movement then there is a tropia
what do you need to carry out a cover test?
pen torch
occluder
near (1/3m) and distant 6m targets
four types of tropias
esotropia
exotropia
hypertropia
hypotropia
define esotropia
outward movement of the eye (convergent)
define exotropia
inward movement of the eye (divergent)
define hypertropia
downward movement of the eye
define hypertropia
upward movement of the eye
what does ocular motility assess?
muscle pairs
what do you need to test ocular motility?
pen torch
examine without glasses
cover 9 position
what in a ocular motility test tells you there is a weak muscle?
there is visible sclera when looking in that direction
three examples of eye movement defects
- VIth nerve palsy
- IVth nerve palsy
- IIIrd nerve palsy
describe VIth nerve palsy
lateral rectus cannot abduct fully so there is visible sclera left when looking outwards
presentation of VIth nerve palsy
horizontal diplopia
causes of VIth nerve palsy in over 50s
microvascular
causes of VIth nerve palsy in under 50s
raised ICP
tumour
congenital
where does the VIth CN run?
it rests of the petrous portion of the temporal bone therefore raised pressure can compress this
describe IVth nerve palsy
superior oblique cannot depress eye so inferior oblique works unopposed (eye can drift up when looking ahead)
presentation of IVth nerve palsy
hypertropia
vertical diplopia
head tilt
causes of IVth nerve palsy
congenital decompensated
microvascular
tumour
bilateral in closed head trauma (shaking of brain in cranial cavity can stretch 4th nerve which is very thin)
describe IIIrd nerve palsy
MR, IR, SR, IO, sphincter pupillae and levator palpebrae superioris are affected
presentation of IIIrd nerve palsy
down and out ptosis dilated pupil diplopia that is both horizontal and vertical (diagonal) exotropia with hypotropia
causes of IIIrd nerve palsy
expanding aneurysm in the brain
tumour
MS
congenital
management of IIIrd nerve palsy
straight for scan
how do you distinguish aneurysm from microvascular in IIIrd nerve palsy?
involvement of the pupil
cause of internuclear ophthalmoplegia
eyes work together due to a connection between the nuclei of the medial longitudinal fasciculus
if affected there is inability to adduct
this can be affected by mass, MS (demyeliantion) or vascular
