Presentation
- Classically a young adult (reported more common in women in their 20s–30s) who notices sudden anisocoria — one enlarged pupil, more noticeable in bright light.
- Photophobia and blurred near vision from accommodative paresis may be present initially and tend to improve over time as tonic accommodation develops.
- Often otherwise asymptomatic and found incidentally, or — if part of Holmes-Adie syndrome — accompanied by reduced/absent deep tendon reflexes and dysautonomic symptoms.
Findings
★ Signature Finding
Light-near dissociation: the pupil reacts poorly (or not at all) to light but shows a slow, tonic constriction to near effort with slow redilation afterward. Mechanism: postganglionic parasympathetic denervation at the ciliary ganglion with aberrant reinnervation favouring the far more numerous accommodative fibres (~30:1 ratio).
- Segmental iris sphincter palsy with vermiform (worm-like) movements of the pupillary border on slit-lamp exam.
- Denervation supersensitivity to dilute pilocarpine — the affected pupil constricts more than the fellow eye — reported in roughly 80% of cases.
- Unilateral in about 80% of cases at onset; the fellow eye can become involved over time. Long-standing Adie pupils can become smaller over months to years ("little old Adie's").
Etiology & Mechanism
- Most cases are idiopathic, thought to follow a viral illness causing postganglionic parasympathetic denervation at or near the ciliary ganglion/short ciliary nerves.
- Holmes-Adie syndrome = tonic pupil plus diminished/absent deep tendon reflexes, sometimes with wider autonomic dysfunction.
- Rare secondary causes include orbital trauma or surgery, herpes zoster ophthalmicus, giant cell arteritis, diabetes, and orbital tumour or inflammation.
Red Flags — Do Not Miss
Critical — Do Not Miss
- Associated ptosis, extraocular motility deficit, or other cranial neuropathy — not features of isolated Adie pupil; their presence points to a different process (e.g., a third nerve palsy) requiring urgent workup.
- An acute, painful red eye with a dilated pupil — first exclude acute angle-closure glaucoma and pharmacologic mydriasis before attributing the finding to Adie pupil.
- Bilateral areflexia with autonomic symptoms in an atypical setting — consider a paraneoplastic or autoimmune autonomic neuropathy.
Investigations
- Dilute pilocarpine test: commonly cited concentrations are 0.1–0.125%, applied to both eyes; the affected pupil shows denervation-supersensitivity constriction at 30–60 min while the normal pupil is largely unaffected.
- Slit-lamp exam for segmental sphincter palsy/vermiform movements is often sufficient without pharmacologic testing when classic findings are present.
- Deep tendon reflex testing (patellar/Achilles) to screen for Holmes-Adie syndrome.
- Neuroimaging is generally NOT required for a classic presentation; reserve for atypical features (other neurologic deficits, pain, or rapid progression).
Management
- Reassurance — the condition is benign and usually does not require treatment.
- Reading glasses to correct bothersome accommodative paresis if present.
Treatment
- No definitive treatment is needed in most cases; observation is appropriate.
- Low-dose pilocarpine (e.g., 0.1%) can be used in select symptomatic patients for cosmetic anisocoria or photophobia, exploiting denervation supersensitivity.
Follow-up
- Routine follow-up is not typically required once the diagnosis is confirmed and its benign nature explained.
- Advise the patient to report any change suggesting fellow-eye involvement over time.
Clinical Pearl
💡 Clinical Pearl
The roughly 30:1 disproportion between accommodative (near) and pupillary light-reflex fibre counts explains why the near response recovers much better than the light response after ciliary ganglion denervation — the defining light-near dissociation of Adie pupil.
Differential Diagnoses
| Condition | Key Distinguishing Point |
|---|---|
| Pharmacologic mydriasis (e.g., atropine) | Pupil fails to constrict even to full-strength (1%) pilocarpine — distinct from Adie's supersensitivity to dilute pilocarpine. |
| Third cranial nerve palsy | Associated ptosis and ophthalmoplegia, acute onset. |
| Argyll Robertson pupil (neurosyphilis) | Bilateral, small/irregular pupils with light-near dissociation, but miotic; do not show supersensitivity to dilute pilocarpine. |
| Traumatic mydriasis (iris sphincter tear) | History of blunt trauma, irregular pupil margin without vermiform movements. |
| Acute angle-closure glaucoma | Painful, mid-dilated fixed pupil with elevated IOP and corneal oedema. |