Management of Mydriasis (Dilated Pupils)
The appropriate management of mydriasis (dilated pupils) requires first identifying the underlying cause through a systematic evaluation of pupillary characteristics, associated symptoms, and potential exposures, followed by targeted interventions based on the specific etiology.
Diagnostic Approach
Initial Pupil Assessment
- Evaluate if mydriasis is unilateral or bilateral
- Check pupillary light reactivity (direct and consensual)
- Assess size, shape, and symmetry of pupils
- Look for associated symptoms (pain, vision changes, headache) 1
Key Historical Elements
- Recent medication use or exposure to:
- Recent trauma or surgery
- Neurological symptoms (headache, altered consciousness)
- Eye pain or redness 1
Etiology-Based Management
1. Pharmacological Mydriasis
Topical/Accidental Exposure
- If suspected contamination with anticholinergic agents:
- Irrigate the affected eye thoroughly
- Reassure patient about temporary nature (typically resolves within 24 hours)
- Document pupil size and monitor for resolution 3
- For severe anticholinergic toxicity with systemic symptoms:
- Consider physostigmine for reversal of both central and peripheral anticholinergic effects
- Physostigmine can produce dramatic reversal within minutes if diagnosis is correct 4
Medication-Induced
- Identify and discontinue offending agent if possible
- For nebulized anticholinergics (e.g., ipratropium):
- Ensure proper mask fit to prevent ocular exposure
- Consider alternative medications if recurrent 2
2. Acute Angle-Closure Glaucoma
- Check intraocular pressure (IOP)
- If elevated IOP with corneal edema, pain, and mid-dilated pupil:
- Immediate medical therapy to lower IOP (aqueous suppressants)
- Perform laser peripheral iridotomy (LPI) once corneal edema clears 1, 5
- Post-iridotomy management includes:
- Topical corticosteroids to reduce inflammation
- IOP monitoring
- Evaluation of iridotomy patency 5
- Prophylactic LPI in the fellow eye if anatomically narrow angle 1, 5
3. Neurological Causes
Third Nerve Palsy
- For pupil-involving third nerve palsy:
- Urgent neuroimaging (MRI with gadolinium and MRA or CTA) to rule out compressive lesions, especially posterior communicating artery aneurysm 1
- If high suspicion despite normal MRA/CTA, consider catheter angiogram 1
- Manage diplopia with:
- Temporary occlusion (patch)
- Botulinum toxin to opposing muscles
- Prisms for residual diplopia 1
Stroke/Brainstem Dysfunction
- For bilateral dilated pupils with altered consciousness:
Special Considerations
Intraoperative Unilateral Mydriasis
- Consider topical exposure to phenylephrine or other agents used during intubation
- Perform "wake-up" test if neurological injury is suspected
- Monitor for changes in vital signs or other neurological indicators 7
Post-Traumatic Mydriasis
- Urgent neuroimaging to rule out intracranial hemorrhage or mass effect
- Ophthalmology consultation for traumatic iris damage
- Serial pupillary examinations to monitor for changes 1
Follow-up Recommendations
- For pharmacological mydriasis: reassess in 24-48 hours for resolution
- For post-iridotomy patients: check IOP within 30 minutes to 2 hours post-procedure 5
- For neurological causes: follow-up based on underlying pathology and treatment plan
Common Pitfalls to Avoid
- Failing to distinguish between pharmacological and neurological causes
- Overlooking inadvertent topical exposure to mydriatic agents
- Assuming bilateral dilated pupils always indicate poor prognosis
- Neglecting to perform compression gonioscopy in suspected angle closure
- Delaying neuroimaging in pupil-involving third nerve palsy 1, 6