What is the appropriate management for a child presenting with dilated pupils (mydriasis)?

Management of Dilated Pupils in a Child

A child presenting with dilated pupils requires systematic assessment of pupil size, symmetry, shape, and light reactivity in dim lighting to determine if the mydriasis is physiologic, pharmacologic, or pathologic—with anisocoria >1mm warranting urgent evaluation for serious neurologic or ocular pathology. 1

Initial Assessment

Pupillary examination must be performed systematically:

• Assess pupil size in dim lighting to accurately detect anisocoria, as differences >1mm may indicate pathologic processes including Horner syndrome, Adie tonic pupil, or third-cranial-nerve palsy 1
• Evaluate pupil shape and symmetry bilaterally, noting any irregularities that may suggest traumatic sphincter damage, iritis, or congenital abnormalities like coloboma 1
• Test direct and consensual light responses by shining a penlight directly into each eye while the child fixates on a distant target 1
• Perform the swinging-light test to detect relative afferent pupillary defects (RAPD), which indicate optic nerve or anterior visual pathway pathology rather than simple mydriasis 1

Critical Diagnostic Considerations

Bilateral vs. Unilateral Mydriasis:

• Bilateral dilated pupils suggest systemic causes including pharmacologic exposure (anticholinergics, antihistamines, tropane alkaloids from Datura plants), toxicologic ingestion, or rare congenital conditions 2, 3, 4
• Unilateral dilated pupil requires urgent evaluation for third-nerve palsy, Adie tonic pupil, trauma, or local pharmacologic contamination 3, 5, 6

Pharmacologic Mydriasis:

• Local contamination with anticholinergic agents (ipratropium, atropine, scopolamine, tropicamide) is a common cause, particularly in healthcare settings or after nebulizer treatments 7, 2, 6
• "Gardener's pupil" from exposure to plants containing alkaloids (Datura species) can cause unilateral or bilateral fixed mydriasis 4
• Systemic anticholinergic toxicity from medications like benztropine presents with mydriasis plus dry mouth, tachycardia, flushed skin, confusion, and hyperthermia 2

Examination Algorithm

Step 1: History Taking

• Medication exposure: Recent use of eye drops, nebulizers (ipratropium), anticholinergic medications, or contact with plants 7, 2, 4, 6
• Trauma history: Any blunt or penetrating eye injury requiring immediate ophthalmology referral 8
• Associated symptoms: Headache, vision changes, neurologic deficits, fever, behavioral changes 7, 2

Step 2: Complete Eye Examination

• Visual acuity testing appropriate for age (fixation and following for infants, recognition acuity for older children) 1
• External inspection for ptosis, proptosis, eyelid abnormalities, or dysmorphic features 1
• Binocular red reflex (Brückner) test to detect media opacities, refractive errors, or strabismus 1
• Ocular motility and alignment testing using cover tests and assessment of extraocular movements 1

Step 3: Pharmacologic Testing (if indicated)

• Pilocarpine 1% testing: Failure to constrict suggests pharmacologic blockade or iris sphincter abnormality; constriction indicates neurogenic causes 9
• Phenylephrine 2.5% testing: Additional dilation suggests intact sympathetic innervation 9

Management Based on Etiology

Pharmacologic Mydriasis:

• Reassurance and observation if history confirms accidental exposure to mydriatic agents 7, 6
• Supportive care for anticholinergic toxicity including physostigmine 1-2mg SC/IV for severe cases, though this is rarely needed for isolated mydriasis 2
• Avoid unnecessary neuroimaging when pharmacologic cause is confirmed 3, 5

Neurologic Causes (Third-Nerve Palsy, RAPD):

• Immediate ophthalmology and neurology consultation for any child with RAPD ≥0.3 log units, as this indicates optic nerve pathology rather than amblyopia 1
• Neuroimaging (CT or MRI) for suspected intracranial pathology 8, 5

Traumatic Mydriasis:

• Urgent pediatric ophthalmology referral for children with eye trauma and vision impairment 8
• CT imaging to evaluate for orbital fractures, muscle entrapment, or structural damage 8
• Cycloplegic agents may be prescribed to reduce pain and prevent complications 8

Congenital Mydriasis:

• Genetic evaluation if bilateral fixed mydriasis present since birth with accommodation failure 9
• Prescribe bifocals and sunglasses for photophobia and accommodation insufficiency 9
• Monitor visual development to prevent amblyopia 9

Key Pitfalls to Avoid

• Do not assume neurologic emergency without performing swinging-light test and obtaining accurate medication/exposure history 3, 5
• Do not overlook local contamination from nebulizers or inadvertent contact with mydriatic drops, especially in hospitalized children 6
• Do not miss plant exposure by failing to ask about gardening or outdoor activities involving Datura or similar plants 4
• Do not delay ophthalmology referral for unilateral mydriasis with vision changes, trauma, or RAPD 1, 8