Pupil Disorders

Question 1

What causes Pupil Constriction?

Answer 1

• Sphincter Pupillae - Parasympathetic Nervous System

Question 2

What causes Pupil Dilation?

Answer 2

• Dilator Pupillae - Arranged like spokes on a bicycle wheel travelling straight from the inside to the outside of the iris.
• Stimulates by the sympathetic nervous system using adrenalin as a neurotransmitter

Question 3

What causes an Abnormal Pupil Shape?

Answer 3

• Trauma to the Sphincter muscles in the iris causes an irregular pupil (caused by cataract surgery and other eye operations)
• Anterior Uveitis: causes adhesions in the iris that make the pupils misshapen
• Acute angle closure glaucoma can cause ischaemic damage to the muscles of the iris causing an abnormal pupil shape, usually a vertical oval
• Rubeosis Iridis (neovascularisation in the iris) can distort the shaped of the iris and pupil - associated with poorly controlled diabetes and diabetic retinopathy
• Coloboma (congenital malformation) - This can cause a hole in the iris causing an irregular pupil shape
• Tadpole pupil- spasm in a segment of the iris causing a misshapen pupil.

Question 4

What are the causes of Mydriasis (dilated pupil)?

Answer 4

• Third nerve palsy
• Holmes-Adie Syndrome
• Raised Intracranial Pressure
• Congenital
• Trauma
• Cocaine
• Anticholinergics

Question 5

What are the causes of Miosis (constricted pupil)?

Answer 5

• Horner’s Syndrome
• Cluster Headaches
• Argyll-Robertson pupil (neurosyphilis)
• Opiates
• Nicotine
• Pilocarpine

Question 6

What is the triad seen in Third Nerve Palsy?

Answer 6

• Ptosis
• Dilated Non-reactive pupil
• Divergent Strabismus (down and out position of the eye)