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Warning-sign checks

Tonic pupil syndrome: when to get help

Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.

  1. 1

    Is any of this happening now?

    Call 911

    Call emergency services if a pupil change occurs with:

    • A sudden severe headache
    • New double vision or abnormal eye movement
    • A newly drooping eyelid
    • Weakness, numbness, confusion or difficulty speaking
    • Collapse or a recent significant head injury

    If you already have a confirmed tonic pupil, arrange follow-up rather than emergency care for gradual changes such as increasing reading difficulty or slowly changing pupil size.

    Other emergency signs, for anyone
    • Someone who is struggling to breathe, gasping, choking, or cannot get words out
    • Someone who has chest pain, tightness or pressure lasting more than a few minutes
    • Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
    • Someone who is unconscious, or cannot be woken
    • Someone who is bleeding heavily and it will not stop with firm pressure
    • Someone who has had a seizure that will not stop, or does not wake up afterwards
    • Someone who has lips or skin that look pale, blue, grey or blotchy
    • Someone who you believe has taken an overdose or swallowed something poisonous
  2. 2

    Is any of this happening?

    Be seen today

    Seek urgent medical assessment for a new or suddenly noticed unequal pupil, particularly if its cause is unknown.

    Although tonic pupil syndrome is usually harmless once confirmed, several other conditions can cause a similar appearance.

    Get same-day urgent eye care for sudden loss of vision or a red, severely painful eye, especially with nausea, vomiting or coloured halos around lights.

    These are not typical features of tonic pupil syndrome.

    New neurological symptoms still need prompt assessment.

  3. 3

    Does any of this apply?

    Book an appointment

    Arrange a routine eye appointment if you have a gradual or longstanding difference in pupil size, persistent light sensitivity, or trouble focusing up close.

    An examination can confirm the pattern and check for other causes.

Every sign above is quoted from the sofidex article on Tonic pupil syndrome. If you are not sure, err upward — it is always reasonable to be checked.