Pupil Disorders Flashcards
What causes pupil constriction?
Parasympathetic signals (using ACh) along fibres on the oculomotor nerve innervate circular muscles on the iris
What causes pupil dilation?
Dilator muscles of pupil stimulated by sympathetic nervous system (using NA)
What can cause an abnormal pupil shape?
Trauma to sphincter muscles Anterior uveitis Acute angle closure glaucoma Rubeosis iridis Colobloma Tadpole pupil
How does trauma cause an abnormal pupil shape?
Irregular pupil due to some contraction/dilation mismatch
Caused by eye surgery
How does anterior uveitis cause an abnormal pupil shape?
Adhesions in the iris
How does acute angle closure glaucoma cause an abnormal pupil shape?
Ischaemic damage to iris muscles
Typically a vertical oval
How does rubeosis iridis cause an abnormal pupil shape?
Neovascularisation of the iris can distort the iris shape
How does coloboma cause an abnormal pupil shape?
Congenital malformation leading to a hole in the iris
How does tadpole pupil cause an abnormal pupil shape?
Spasm in a segment of iris - causes temporary misshapen pupil
What is mydriasis?
Dilated pupil
What can cause mydriasis?
Third nerve palsy Holmes-Adie syndrome Raised ICP Congenital Trauma Anticholinergics
What is miosis?
Constricted pupil
What can cause miosis?
Horner's syndrome Cluster headaches Argyll-Robertson pupil Opiates Nicotine Pilocarpine
What is a Holmes Adie pupil?
Unilateral dilated pupil that is slow to react to light
Caused by damage to post ganglionic parasympathetic fibres
What is Holmes Adie syndrome?
Holmes Adie pupil
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Absent ankle + knee reflexes
