Diseases of Visual Pathways/Dysfunction Flashcards
What is anisocoria & it is present in what percent of the population?
(unequal pupil size) variant of normal
20%
What are the components of an eye exam?
- V. A. testing
- V. F. testing
- confrontation
- amsler grid
- color perception & saturation
- pseudochromatic plates
- red cap test
Describe the pathway of the pupilary reflex
- affarent (optic nerve taking info of light source to midbrain)
- synapse in pretectal nucleus
- following neuron synapses in CN III nucles
- only one nucleus - shared btw eyes, which is why we get consensual pupilary response
- CN III exits anterior brains stem with parasympathetic fibers
- synapse in ciliary ganglion
- final neruron innervates the pupil
How do we assess ocular motility?
cardinal fields of gaze
What is the term for misalignment of the eyes?
strabismus
What is the term for limitation of movement in one eye?
duction
What is the term for limitation of conjugate gaze?
version
Describe the sympathetic innervation of the eye & face
- (origination sympathetic innervation eye & face) - hypothalamus
- descend to midbrain & pons - terminate C8-T2 & synapses in iteromediolateral cells of spinal cord
- exits central nervous system T1(still preganglionic) & move through sympathetic chain to synapse at superior cervical ganglion (C3/C4)
- these postganglionic fibers are pseudomotor & vasomotor fibers
- follow external carotids (innervate sweat glands & vessels of the face)
- follow internal carotids (cavernous sinus; join CN VI into orbit & exit as long ciliary nerves)
- these postganglionic fibers are pseudomotor & vasomotor fibers
What is the difference between true diplopia & monocular diplopia?
- true diplopia
- two separate images, one of which disappears when either eye is closed
- monocular diplopia
- not eliminated by closing the fellow eye
- refractive problem, dry eye, or cataract
Vertical diplopia is associated with palsy of what CN?
CN IV
Horizontal diplopia is associated with palsy of what CN?
CN VI
What should you do if a patient comes in complaining of double vision?
thorough neurologic history & physical
What type of ptosis is seen with a CN III palsy?
complete ptosis
An eye cannot move in which direction in a CN III Palsy?
cannot adduct or look superior
An eye cannot move in which direction in a CN IV Palsy?
cannot depress
What does papilledema look like ona fundoscopic exam?
the nerve fiber starts to cover the vein on the side
& the disc appear larger than it should
(looks like an innertube)
Identify where the lesion is occurring for locations 1-8 & the resulting visual impairment
- Optic nerve lesion
- complete loss of visual field of one eye
- Optic nerve lesion close to chiasm
- Superior temporal cut in oposite eye
- Lesionis optic chiasm
- true bitemporal visual field defect
- Lesion in optic tract
- homonomous hemianopsia (loss of same field)
- Temporal defect
- “pie in the sky”
- lesion in lateral geniculate nucleus
- homonomous hemianopais (same as 4)
- Parietal defect
- inferior field defect
- Occipital defect
- usually some sparing of macular visual field d/t multiple bood supplies
