Dilated pupil (mydriasis) (blown pupil)

• brain swelling / bleeding that has progressed to compression of CN III (usually from cerebral herniation) - unopposed sympathetic stimulation

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Drugs

• drugs will dilate the pupils but they will still react to light

• anticholinergic drugs:

  • atropine

  • scopolamine

  • cyclopentolate

  • tropicamide

• alpha1-agonists: phenylephrine.

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Oculomotor nerve palsy (3rd cranial nerve)

• parasympathetic nerves are in the superficial parts of the nerve, so tend to be more vulnerable to compressive lesions and spared by vascular lesions (e.g. diabetes mellitus).

• If an acute third nerve palsy is accompanied by pupillary mydriasis an aneurysm arising from the posterior communicating artery must be excluded

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Others:

• Holmes-Adie pupil (tonic phase)

• post-traumatic iridocyclitis (e.g. direct facial trauma)

• acute closed-angle glaucoma

• physiologicalanisocoria

• ocular prosthesis – the normal pupil may be relatively constricted due to ambient light.

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Constricted pupil (miosis)

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Anisocoria 

• one pupil being more dilated than the other

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Fundoscopic Exam

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Normal Anatomy

• optic disk

• optic cup

• retinal artery/vein

• macula

• fovea

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Pathology

• papilledema: optic disk swelling

  • hemorrages​

  • exudate

  • narrow vessels

  • edema of the optic disk

• glaucoma

• optic neuritis

• macular degeneration

• cataracts

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