Anisocoria (unequal pupil size)
Disclaimer
These guidelines have been produced to guide clinical decision making for general practitioners (GPs). They are not strict protocols. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.
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Referral to Emergency Department:
If any of the following are present or suspected, please refer the patient to the Emergency Department (via ambulance if necessary) or seek emergency medical advice if in a remote region.
- Acute onset anisocoria (unequal pupil size)
- Presence of neurological signs
- Sudden vision loss
- Signs or symptoms suggestive of raised intracranial pressure (e.g. severe headache, altered conscious state)
Immediately contact on-call registrar or service to arrange an immediate Ophthalmology (Paediatric) assessment (seen within 7 days):
- Leukocoria (absent red reflex) - absent, dull, shadows, or asymmetrical results on red reflex test
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Introduction
A condition characterised by an unequal size of the eye’s pupils.
Pre-referral investigations
Examination
- Cranial nerve examination
- For children aged < 5 years: comment on visual behaviour/acuity
- Red reflex
- Relative Afferent Pupillary Defect (RAPD)
- Height/length and weight
Pre-referral management
When to refer
Refer to the Ophthalmology Department
- Sub-acute (≥ 2 weeks) anisocoria (unequal pupil size)
- Child aged < 1 year with anisocoria (unequal pupil size)
How to refer
- Routine non-urgent referrals from a GP or a Consultant are made via the Central Referral Service
- Routine non-urgent referrals from a nurse practitioner, non-medical referrers or private hospitals are made via the PCH Referral Office (Fax: 6456 0097 or email PCH.Referrals@health.wa.gov.au)
- Urgent referrals (less than seven days) are made via the PCH Referral Office. Please call Perth Children’s Hospital Switch on 6456 2222 to discuss referral with the relevant speciality registrar.
Essential information to include in your referral
History
- Details of previous treatment and outcome
Examination
- Cranial nerve examination
- For children aged < 5 years: comment on visual behaviour/acuity
- Red reflex
- Relative Afferent Pupillary Defect (RAPD)
- Height/length and weight
- Growth percentiles / z-scores where relevant
Investigations
- Previous ophthalmology or optometry reports
Useful resources
- Royal Children’s Hospital Melbourne Clinical Practice Guideline: Eye Examination
| Reviewer/Team: |
Ophthalmology Department, PCH |
Last reviewed: |
May 2026 |
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