Eye and Neurology Flashcards
Describe the difference between Optic disc swelling and papilloedema?
Optic disc swelling is a descriptive term and can describe disc swelling secondary to any cause
Papilloedema describes bilateral optic disc swelling secondary to raised ICP.
Why can raised ICP cause raised IOP?
Raised ICP is transmitted along the subarachnoid space which is continuous with the subarachnoid space surrounding the optic nerve.
Until proven otherwise all patients with bilateral disc swelling should be suspected of….
Raised ICP due to space occupying lesion until proven otherwise
3 causes of raised ICP and papilloedema?
BRAIN: space occupying lesion
BLOOD: Malignant hypertension
CSF: Idiopathic Intracranial hypertension (problem with CSF circulation/ drainage/ production)
Presentation of papilloedema?
Produces few symptoms. Symptoms are usually due to the underlying cause.
If chronic disc swelling when the swelling subsides the disc becomes atrophic and pale and loss of visual function and blindness can occur.
Describe the difference between monocular and binocular double vision, what does this tell you?
Monocular: cover one eye and still double
Binocular: goes away when cover eye > NEUROLOGICAL PROBLEM
Lesions posterior to the optic chiasm produce what kind of field defects?
Homonymous field defect (involvement of the same side in both eyes as information from the two visual hemifields is separated beyond this point.
Lesions damaging the optic chiasm cause?
Bitemporal defects
Common causes of cranial 6 nerve palsy?
Increased ICP, Infiltration of nerve sheath by tumours, microvascular ischaemia (can occur in diabetics)
What muscle is effected in cranial nerve 6 palsy?
Lateral rectus muscle
Presentation of cranial nerve 6 palsy?
Cannot abduct the eye and have medial deviation of the eye. Horizontal diplopia more commonly when looking far away or in direction of the affected eye.
Causes of cranial nerve 4 palsy?
Congenital, head trauma
What muscle is effected in cranial nerve 4 palsy?
Superior oblique muscle
Presentation of cranial nerve 4 palsy?
Problems moving eye inferomedially
Torsional diplopia (2 objects at an angle)
When asked to gaze to the right eye moves superior as well as medial
Patient often tilts their head to correct the double vision
Causes of cranial nerve 3 palsy?
Aneurysm, infarction (diabetes and atheroma), tumour, MS (autoimmune condition attacking the nervous system)
What muscles are effected in cranial nerve 3 palsy?
Medial rectus, superior rectus, inferior rectus, inferior oblique, LPS and sphincter pupillae
Presentation of cranial nerve 3 palsy?
Can only abduct and depress the eye slightly > DOWN and OUT appearance
Ptosis of eyelid due to paralysed LPS and dilated pupil (may be sparing)
What can sparing or involvement of the pupil in cranial nerve 3 palsy suggest?
No sparing of the pupil suggests a compressive session as parasympathetics run on the outside of the nerve
Sparing of the pupils may indicate a microvascular problem (infarction in diabetes) as this would effect the middle of the nerve.
Painful 3rd nerve palsy effecting the pupil?
Aneurysm
Optic nerve lesions will cause what visual field defect?
Unilateral visual loss
Right optic nerve causes right vision loss and vice versa
Causes of optic nerve related vision loss?
Optic neuritis in MS, trauma, compression, ischaemia optic neuropathy, infection, papilloedema.
Describe presentation of optic neuritis?
Unilateral progressive visual loss, pain behind the eye especially with movement, disc may appear normal
Course of optic neuritis?
usually gradually recovers with no treatment
Optic chiasm lesions cause what type of visual field defect?
Bitemporal hemianopia
Causes of bitemporal hemianopia?
Pituitary tumours, meningioma, carniopharyngioma
What type of visual field defect do optic tract lesions cause? Why?
Homonymous (effects same side) hemianopia
Once you are past optic chiasm right brain is taking all left and left all right
What type of visual field defect does occipital cortex problems cause?
Homonymous hemianopia often with macular sparing as information from the macula takes up such a large area
Causes of occipital cortex visual problems?
Stroke and demyelination
What could cause an inferior quadrantopia? Why?
Parietal lobe lesion
parietal takes lower field so lesion causes loss of inferior quadrant on other side
What causes homonymous hemianopia with macular sparing?
Occipital cortex problem
What causes homonymous hemianopia?
Optic tract lesions
Occipital cortex problem (may however be macular sparing)
What could cause a superior quadrantopia? Why?
temporal lobe lesion
temporal takes upper field so lesion causes loss of superior quadrant on other side
Commonest cause of horizontal diplopia?
Vascular issue with CN6
