What is the appropriate management for a patient with anisocoria?

Management of Anisocoria

The appropriate management for anisocoria begins with determining which pupil is abnormal by checking pupillary responses in both bright and dim illumination, followed by assessment for associated findings such as ptosis, extraocular movement limitations, or other neurological signs. 1

Initial Assessment

• Determine which pupil is abnormal:

  • In bright light: If the larger pupil is abnormal, anisocoria will be more pronounced 1, 2
  • In dim light: If the smaller pupil is abnormal, anisocoria will be more pronounced 1, 2

• Assess for associated symptoms and signs:

  • Ptosis (drooping eyelid) 1
  • Extraocular movement limitations 1
  • Headache, especially new or severe 1
  • Visual disturbances 3
  • Other neurological deficits 1

Diagnostic Algorithm

1. Physiological Anisocoria

• Small difference in pupil size (usually <1mm) 1
• Relatively constant in different lighting conditions 1
• No associated symptoms 2
• Management: Reassurance, no further testing needed 2

2. Larger Pupil Abnormal (More obvious in bright light)

A. Pharmacological Mydriasis

• History of exposure to mydriatic agents or nebulized medications 4
• Pupil unreactive to light 4
• No associated neurological findings 4
• Management:
  • Pilocarpine test (1% solution): No constriction confirms pharmacological cause 4, 5
  • Observation until effect wears off (typically 24 hours) 4
  • For nebulized medications: Prevent recurrence with better-fitting masks or eye protection 4

B. Adie's Tonic Pupil

• Typically affects young women 3
• Poor or slow reaction to light 6
• Vermiform movements of iris 6
• Management:
  • Pilocarpine test (0.1% solution): Hypersensitive constriction confirms diagnosis 5
  • Low-dose pilocarpine drops if symptomatic 5

C. Third Nerve Palsy

• URGENT EVALUATION REQUIRED 1
• May have associated ptosis and extraocular muscle weakness 1
• Management:
  • Immediate neuroimaging (MRA or CTA) to rule out posterior communicating artery aneurysm 1
  • Neurosurgical consultation if aneurysm identified 1

3. Smaller Pupil Abnormal (More obvious in dim light)

A. Horner's Syndrome

• Miosis, mild ptosis, and sometimes anhidrosis 5
• Management:
  • Cocaine test (10% solution): No dilation confirms Horner's syndrome 5
  • Hydroxyamphetamine test to localize the lesion 5
  • Imaging based on suspected etiology:
    • Brain and neck imaging if acute onset 6
    • Chest imaging if suspected lung apex tumor 6

B. Cavernous Sinus Lesions

• May present with multiple cranial nerve palsies (III, IV, VI, V1) 1
• Management:
  • MRI with contrast of brain/orbits 1
  • Referral to neurology or neurosurgery 1

Red Flags Requiring Urgent Evaluation

• New-onset pupil-involving third nerve palsy 1
• Anisocoria with headache, altered mental status, or other neurological deficits 1
• Anisocoria with signs of increased intracranial pressure (papilledema, decreased consciousness) 1
• Anisocoria following head trauma 7
• Anisocoria with preoperative Glasgow Coma Scale motor response ≤5 7

Special Considerations

• In traumatic brain injury patients with anisocoria and other severity signs, ICP monitoring is suggested 7
• For patients with benign episodic mydriasis (often associated with migraine), neuroimaging is not recommended in the absence of other symptoms 3
• Pharmacological testing should be performed before expensive neuroimaging in cases without other neurological signs 5

Follow-up

• Physiological anisocoria: No follow-up needed 2
• Pharmacological anisocoria: Resolution within 24 hours 4
• Pathological causes: Follow-up based on underlying etiology and specialist recommendations 1