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 Abnormal Pupils
Bilateral Pupillary Dilation
- Cerebral lesion - herniation, encephalitis, visual cortex infarct, tumour, trauma, MS
- Drugs - anticholinergics, SSRIs / SNaRIs, stimulants, barbiturates, methanol
- Brain stem death
Bilateral Pupillary Constriction
- Drugs - opiates, antipsychotics, acetylcholine, clonidine
- Intracranial haemorrhage
- Horner's syndrome (bilateral) - autonomic failure, amyloidosis, diabetes
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 Perform
- 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
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