Eyes Flashcards
Causes of anosmia?
URTI Meningioma of the olfactory groove Ethmoid tumours Head trauma Meningitis Hydrocephalus Congenital
Explain the light reflex
Constriction of the pupil in response to light is relayed via the optic nerve and tract –> the superior quadrigeminal brachium –> the edinger-westphal nucleus –> ciliary ganglion
Explain the accommodation reflex
Originates in the cortex and is relayed via parasympthatic fibres in the third nerve
Causes of absent light reflex but intact accommodation reflex?
Midbrain lesion
Ciliary ganglion lesion
Parinaud’s syndrome
Bilateral anterior visual pathway lesions
Causes of absent convergence but intact light reflex?
Cortical lesions
Causes of constriction?
Horner's syndrome Argyll Robertson pupil Pontine lesions Narcotics Old age
Causes of dilation?
Mydriatics, atropine, cocaine Third nerve lesion Adie's pupil Iridectomy Post trauma Congenital
Causes of Horner’s syndrome?
Carcinoma of the lung apex Neck - malignancy or trauma Carotid artery lesion Brain stem lesion Retro-orbital lesions Syringomyelia
What is Adie’s syndrome
Caused by lesions in the efferent parasympathetic pathway - infection or inflammation YOUNG WOMEN Dilated pupils - atonic Decreased reaction to light Slow accommodation to light Decreased tendon reflexes
Signs of Argyll Robertson Pupil?
Small, irregular, unequal pupil
No reaction to light
Reaction to accommodation
LOOKS FOR ASSOCIATED TABES
Causes of Argyll Robertson Pupil?
Syphilis
DM
Alcohol
Other midbrain lesions
Causes of Papilloedema?
Space occupying lesions Hydrocephalus Idiopathic intracranial HTN HTN Central retinal vein thrombosis GBS
Causes of ptosis with normal pupils?
Senile ptosis Myotonic dystrophy FSH dystrophy Ocular myopathy Thyrotoxic myopathy Myasthenia gravis Congenital
Causes of ptosis with constricted pupils?
Horner’s syndrome
Tabes dorsalis
Causes of ptosis with dilated pupils?
Third nerve lesion
Clinical features of a third nerve palsy?
Complete ptosis
Divergent strabismus - eye down and out
Dilated pupils that are unreactive to light and accommodation
How to exclude a fourth nerve palsy with a third nerve palsy?
Get patient to look down and across to the opposite side of the lesion - LOOK FOR INTORTION
Superior oblique muscle –> intortion
Central causes of a third nerve palsy?
Vascular Tumour Demyelination Trauma Idiopathic
Peripheral causes of a third nerve palsy?
Compression - aneurysm, raised ITP, cancer. Tolosa-hunt syndrome, meningitis
Infarction
Trauma
Cavernous sinus lesions
Sings of a sixth nerve palsy?
Failure of lateral movement
Affected eye is deviated inwards
Diplopia
Causes of a bilateral sixth nerve palsy?
Trauma
Wernickes encephalopathy
Raised ITP
Mononeuritis multiplex
Causes of a unilateral sixth nerve palsy?
Vascular Tumour Wernickes MS DM Idiopathic Raised ITP
What is one and a half syndrome?
Caused by loss of the MLF and abducens nucleus on the same side.
Only movement is abduction of the contralateral eye
Causes of horizontal nystagmus?
Vestibular lesion
Cerebellar lesion
Internuclear opthalmoplegia
