Pupillary Examination
November 28th, 2019
Inspection of Pupils
Look For
- The size of the pupils (dilated, normal, constricted) and equality of size bilaterally.
Normal Pupillary Size
- In the dark - 4-8mm
- Under bright light - 2-4mm
Causes of Bilateral Pupillary Dilation
- Cerebral lesion - herniation, encephalitis, visual cortex infarct, tumour, trauma, MS
- Drugs - anticholinergics, SSRIs / SNaRIs, stimulants, barbiturates, methanol
- Brain stem death
Causes of Bilateral Pupillary Constriction
- Drugs - opiates, antipsychotics, acetylcholine, clonidine
- Intracranial haemorrhage
- Horner's syndrome (bilateral) - autonomic failure, amyloidosis, diabetes
Causes of Unequal Pupils (Anisocoria)
- Physiological (20% of the population - compare with an old photo)
- Migraine
- Post-ictal
- Horner's syndrome (unilateral)
- Drugs applied to one eye - pilocarpine, tropicamide, cocaine
- Intraocular conditions - glaucoma, retinal detachment
- Optic (II) or oculomotor (III) nerve lesion - trauma, compression, optic neuritis, Guillain barré
- CNS lesion - trauma, tumour, haemorrhage, infarct, MS
Pupillary Light Reflexes
How to Elicit
- Shine a light into each pupil. Watch to see that both the ipsilateral (direct response) and contralateral (consensual response) pupils constrict as a result of the stimulus.
Causes of Absent Pupillary Reflexes
- Intraocular conditions - glaucoma, retinal detachment
- Optic (II) nerve lesion - trauma, compression, optic neuritis
- Midbrain lesion - encephalitis, tumour, trauma, haemorrhage, MS, midbrain infarct
- Oculomotor (III) nerve lesion - trauma, compression, small vessel ischaemia, Guillain barré
- Medications - sympathomimetic, parasympatholytic (anticholinergics), barbiturates, methanol
Interpretation
- No direct response - absent reflex in the tested eyeIpsilateral oculomotor nerve (III) lesion
- No consensual response - absent reflex in opposite eyeContralateral oculomotor nerve (III) lesion
- No afferent response - absent reflex in one eye when testing either eyeIpsilateral optic nerve (II) lesion
- No response - absent reflex in both eyes when testing either eyeMidbrain lesion, medications
Swinging Light Test
How to Perform
- Shine a light into one eye, swing it into the other eye, and so on back and forth.
Interpretation
- A relative afferent pupillary defect (RAPD) is present if the affected eye dilates, or constricts briefly followed by dilatation.
Causes of RAPD
- Intraocular haemorrhage
- Retinal detachment
- Optic or oculomotor nerve lesion
- Midbrain lesion
Accommodation
How to Assess
- Ask the patient to focus on a distant object, such as the back wall of the room. Place a finger in front of their field of view and ask them to look at it.
Causes of Impaired Accommodation
- Optic (II) nerve lesion - trauma, compression, optic neuritis
- Thalamic / occipital / midbrain lesion - encephalitis, tumour, trauma, MS, midbrain infarct
- Oculomotor (III) nerve lesion - trauma, compression, small vessel ischaemia, Guillain barré
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