What causes Adie's pupil?

Causes of Adie's Pupil

Adie's pupil is primarily caused by damage to the ciliary ganglion or postganglionic short ciliary nerves, with most cases being idiopathic, though viral infections, peripheral neuropathies, and ocular procedures like laser photocoagulation have been implicated as potential triggers. 1, 2

Pathophysiology

Adie's pupil results from damage to the parasympathetic innervation of the eye, specifically affecting:

• The ciliary ganglion
• Postganglionic short ciliary nerves that supply the pupillary sphincter and ciliary muscle 1

This damage leads to:

• A tonically dilated pupil unresponsive to light
• Segmental paralysis of the iris sphincter
• Denervation hypersensitivity to dilute cholinergic agents (0.125% pilocarpine)
• Often associated accommodative paresis 3

Common Causes

1. Idiopathic (most common)

   • Accounts for the majority of cases
   • More common in young women (female-to-male ratio of 2.6:1) 3
   • Mean age of onset around 32 years 3

2. Infectious diseases

   • Viral infections (particularly hepatitis A and B) 4
   • Syphilis (most common infectious cause - approximately 1 in 6 patients may have positive serology) 3, 2
   • Other bacterial infections

3. Autoimmune disorders

   • Various immune-mediated diseases can damage the ciliary ganglion 2

4. Ocular procedures

   • Laser photocoagulation of the peripheral retina 1
   • More extensive laser treatment correlates with more severe symptoms

5. Peripheral neuropathies

   • Generalized peripheral neuropathy can manifest with tonic pupil 3

6. Paraneoplastic syndromes

   • Associated with various malignancies 2

7. Local trauma

   • Damage to the ciliary ganglion or short ciliary nerves 3

Clinical Presentation

Patients with Adie's pupil typically present with:

• Unilateral mydriasis (initially, though approximately 4% per year develop involvement of the second eye) 3
• Poor light reactivity with preserved near response (light-near dissociation)
• Segmental iris sphincter paralysis visible on slit-lamp examination
• Accommodative difficulties (blurred vision, especially for near work)
• Photophobia
• Possible associated deep tendon reflex abnormalities (when part of Adie's syndrome) 4

Diagnostic Approach

1. Pupillary examination

   • Assess size, shape, and symmetry (anisocoria >1mm is clinically significant)
   • Test light and near reactions
   • Look for segmental iris sphincter paralysis on slit-lamp examination 5

2. Pharmacologic testing

   • Dilute pilocarpine test (0.125%) - positive response (pupillary constriction) confirms denervation hypersensitivity 1, 4

3. Rule out other causes of mydriasis

   • Third nerve palsy (look for ptosis and extraocular muscle involvement)
   • Pharmacologic mydriasis (anticholinergic agents)
   • Argyll-Robertson pupil (syphilis)
   • Congenital mydriasis 2

Management

Most cases of Adie's pupil are benign and self-limiting, with symptoms improving over time:

• Reading glasses may be needed initially for accommodative paresis but are often discarded as accommodation recovers 3
• Dilute pilocarpine drops (0.125%) can be used to treat symptomatic mydriasis and improve near vision 2
• Treatment of any underlying cause (if identified)
• Patient reassurance about the benign nature of the condition

Prognosis

• The condition is generally benign
• Pupil size may decrease over time
• Accommodative function often improves
• Approximately 4% of unilateral cases develop involvement of the second eye per year 3
• Most symptoms improve within several months without specific treatment 1

Key Points to Remember

• Adie's pupil is more common in women and typically presents in the third decade of life
• Always check for syphilis serology in patients with tonic pupil
• The condition can be bilateral or become bilateral over time
• While most cases are idiopathic, always consider potential underlying causes
• The diagnosis is confirmed with the dilute pilocarpine test
• Prognosis is generally good with spontaneous improvement in most cases