VF defects, double vision and optic disc swelling Flashcards
Lesion anterior to the chiasm =
Unilateral defect
Lesion posterior to the chiasm =
Contralateral homonymous defect
Chiasmal lesion =
Bitemporal hemianopia (generally)
Features of homonymous hemianopia:
Bilateral so post-chasm
Same side
More congruous = closer to occipital cortex
Commonly caused by stroke
Lesion of inferior optic radiations as they pass through the parietal lobes causes…
Quadrantopia
e.g. right homonymous inferior quadrantopia is from a lesion of the upper optic radiation in the parietal lobe
Features of bitemporal hemianopia:
Lesion at the chasm
Initially incomplete and asymmetric and progresses
Commonly neoplastic
What VF defect does a pituitary tumour often cause?
Bitemporal superior quandrantopia (often asymmetric and respect the vertical midline but not horizontal)
Bitemporal hemianopia with tumour progression
What is the cause and effect of central VFD?
Caused by macula degeneration (commonest form is age related but could be nutritional, toxic etc)
Effect is decrease in VA and colour vision
Associated symptoms of VFD:
Headache and neurological symptoms Photopsia Pain CV problems Pituitary problems
Causes of diplopia:
CN III, IV, VI palsies (diabetes and hypertension) Globe displacement Decompensation of latent squint Myasthenia graves Thyroid eye disease
What does abnormal head posture imply?
Recent onset diplopia
What is strabismus?
Misalignment of one of the eyes from fixating straight ahead
What is monocular diplopia?
Double vision which persist when one eye is covered
‘Ghosting’
What causes monocular diplopia?
Corneal abnormalities e.g. scarring
Uncorrected refractive error (uneven light splitting)
Cataract
What is binocular diplopia?
Both eyes misaligned in straight ahead/various positions of gaze
May be due to motor nerves or extra ocular muscles
Tests in diplopia:
VA Abnormal head position Refraction Motility Cover test
What does posterior communicating artery aneurysm cause?
Painful unilateral CN III palsy
Character of diabetes/hypertension driven CN III palsy?
Spares the pupil
Character of CN III palsy diplopia:
Eye in a down and out position +/- a dilated pupil
(exo hypo deviation)
Because SO and LR are now unopposed
Character of CN IV palsy diplopia:
Cannot carry out intorsion to bring eye in and down towards nose
Abnormal head position - tilt away from side of lesion
Eye will deviate up as it approaches the nose
Unilateral or bilateral
CN IV supplies superior oblique
Treatment of CN IV palsy:
In children treat any amblyopia and correct refractive error
Prisms
Surgery to improve diplopia and for cosmetic reasons
Character of CN VI palsy diplopia:
Failure in abduction of the eye
Horizontal diplopia worse when looking to affected side
AHP - head turn to same side
Eso deviation on cover test (nasal direction)
CN VI supplies lateral rectus
Cause of CN VI palsy:
Hypertension/diabetes, neoplasm, trauma, infection
MS
Transient in neonates
Benign causes 1-3 weeks after viral infection
Tests with optic disc swelling:
CN II
VA and VF
Colour
Pupil reactions
Unilateral causes of optic disc swelling:
CRVO
non-AION and AION (GCA)
Papillitis - inflammation of the optic nerve head
Neuroretinitis - inflammation of optic nerve and peripapillary retina
Bilateral causes of optic disc swelling:
Intracranial mass raising ICP (papilloedema)
Malignant hypertension
Optic disc druse (calcifications) can cause pseudopapilloedema but usually asymptomatic
Exams for optic disc swelling:
CNs
Rule out systemic hypertension, raised ICP and GCA
Bilateral funds exam
Test for proptosis
What is proptosis?
Forward displacement of the eye anteriorly
