pupil problems

Question 1

what controls pupil constriction

Answer 1

circular muscles in the iris that are stimulated by the parasympathetic nervous system using acetylcholine as a neurotransmitter. travels along the occulomtoor nerve (3rd CN)

constriction= parasympathetic
dilation= sympathetic (fight of flight, need plenty of vision)

Question 2

what controls pupil dilation

Answer 2

dilator muscles travel from inside to the outside of the iris

sympathetic nervous system using adrenaline as a neurotransmitter

Question 3

what pathologies can cause abnormal pupil shame

Answer 3

1) trauma to sphincter muscle in iris (operation)
2) anterior uveitis (adhesions/scar tissue) (star?)
3) glaucoma (ischaemia - vertical oval shape)
4) rubeosis iris (distort
5) coloboma (congenital malformation- hole in iris)
6) tadpole pupil (spasm) (associated with migraine)

Question 4

causes of a dilated pupil

Answer 4

Third nerve palsy
Holmes-Adie syndrome
Raised intracranial pressure
Congenital
Trauma
Stimulants such as cocaine
Anticholinergics

Question 5

causes of mitosis (constricted pupil)

Answer 5

Horners syndrome
Cluster headaches
Argyll-Robertson pupil (in neurosyphilis)
Opiates
Nicotine
Pilocarpine*

Question 6

third cranial nerve

Answer 6

oculomotor nerve
supplies all extraoccular muscles except lateral rectus (abducent 6th) and superior oblique (trochlear 4th)

levator palpeerde superioris (lifting upper eyelid)

parasympathetic fibres (innervates the sphincter muscles of iris)

Question 7

third nerve palsy

Answer 7

1) if the third cranial nerve is damaged only SO and LR work so down and out
2) ptosis (cannot lift upper eyelid)
3) usually constricts pupil = dilates
* idiopathic, diabetes, HTN, sivhaemia (if parasympathetic is spared)
* full 3rd nerve palsy- idiopathic trauma, tumor, raised IOP, cavernous sinus thrombosis and PCA aneurysm

Question 8

what is Horner syndrome

Answer 8

damage to the sympathetic nervous system supplying the fact (spinal cord- pre ganglion nerve - sympathetic ganglion- post ganglioncnerves)

• anhidrosis
• ptosis
• miosis

Central lesions (4 Ss):
S – Stroke
S – Multiple Sclerosis
S – Swelling (tumours)
S – Syringomyelia (cyst in the spinal cord)

Pre-ganglionic lesions (4 Ts):
T – Tumour (Pancoast’s tumour)
T – Trauma
T – Thyroidectomy
T – Top rib (a cervical rib growing above the first rib above the clavicle)

Post-ganglionic lesion (4 Cs):
C – Carotid aneurysm
C – Carotid artery dissection
C – Cavernous sinus thrombosis
C – Cluster headache

congenital- heterochromia (difference in colour of iris)

Question 9

cocaine eye drops

Answer 9

test Horner syndrome
stops noradrenaline re-uptake at the neuromuscular junction and normally causes it to dilate but in Horner syndrome the nerves are not releasing noradrenalin so there is no reaction

Question 10

holmes aide pupil

Answer 10

unilateral dilated pupil slugging to react to slight and slow dilation of the pupil following constriction

damage to post ganglionic parasympaethtic fibres

absent ankle and knee flexes

Question 11

argyll robertson pupil

Answer 11

neurosyphilis
constricted pupil that accommodates when focusing on near object but doesn’t react to light

‘prostitues pupil’
‘accommodates but does not react’