1.9 Horner’s Syndrome (Oculosympathetic Palsy)

eyes.nhs.scot/
Eyecare Guidelines/
Section 1 - Eyelids/
1.9 Horner’s Syndrome (Oculosympathetic Palsy)

Date of last review:

22/6/2026

Date of next review:

22/6/2028

Date of publication:

17/8/2026

Differential diagnosis ⁽¹⁾

Mechanical causes of anisocoria or ptosis, including:
- Posterior synechiae
- Iris sphincter tears
- Surgical or traumatic iris injury

Possible management by Optometrist

Advice ⁽¹⁾

Take a thorough history, including:
- Use of new or topical medications affecting pupil size
- Associated visual, neurological, or systemic symptoms
- History of malignancy
- Recent head, neck, or facial trauma
Review old photographs where physiological anisocoria is suspected
Perform slit‑lamp examination to exclude mechanical causes
Assess:
- Extraocular motility
- Presence and degree of ptosis

Signs of Horner’s Syndrome

Classically characterised by a triad of:
- Ipsilateral ptosis
- Miosis
- Anhidrosis
All features are rarely present together
Ptosis, when present, is typically mild (1–2 mm) and may be absent
Miosis is associated with a dilation lag, with anisocoria more evident in the dark
Anhidrosis may involve the entire hemiface, a localised area, or be absent, depending on lesion location
Onset very early in life may result in iris heterochromia

Treatment ⁽¹⁾

No treatment is required for this condition

Typical dosage/duration

(Blue text = IP, black text = non-IP)

Not applicable for this condition ⁽⁷⁾

Further management options ⁽¹⁾

Immediate emergency referral is required if Horner’s syndrome is associated with neck pain
- This should be considered a neurological emergency, as it may indicate carotid artery dissection

No referral normally required:

Physiological anisocoria
Tonic pupil
Manage with reassurance and routine review as appropriate

Possible management in secondary care or local/community pathways where available ⁽¹⁾

Investigation and management is often undertaken by a multidisciplinary team, depending on the underlying cause

College of Optometrists Clinical Management Guideline⁽¹⁾ 

Abnormalities of the pupil - College of Optometrists *

* With special thanks to The College of Optometrists for providing the evidence framework for diagnosis and management from the Clinical Management Guidelines (CMGs) for this condition. All references to the College/CMGs are included where appropriate and form the basis of the Community Eyecare Guidelines.

Guidance is informed by the following sources

College of Optometrists Clinical Management Guidelines Clinical Management Guidelines - College of Optometrists
Advisory alignment with the College of Optometrists Formulary Optometrists' Formulary - College of Optometrists
Advisory alignment with the BNF BNF (British National Formulary) | NICE
Advisory alignment with the Summary Product Characteristics taken from the EMC Home - electronic medicines compendium (emc)
Advisory alignment with Scottish Health Board formularies (where a clear majority is present) *
Advisory alignment with expert consensus (CEGG), informed by sources 2-5 above
Advisory alignment with expert consensus (CEGG)
“Annex C of the Statement” https://www.eyes.nhs.scot/for-professionals/legislation/

* Scottish formularies should be available within the Prescribing section of your Health Board pages on the eyes.nhs.scot website. If unavailable, contact your local Health Board for further information; Health Boards landing page

If you have a query relating to this page, please email NSS.ComEyecareGuidelineGroup@nhs.scot

Disclaimers

CEG disclaimer for guidelines awaiting update:

The Eyecare Guidelines area of the eyes.nhs.scot website (“Website”) is intended as a reference source for education and clinical decision support and is intended for use by ophthalmic healthcare professionals working in Scotland.

As such, the Eyecare Guidelines are not intended for use by the general public and do not replace the advice of a healthcare professional. Members of the public should seek advice directly from their optometrist.

Before reading the Eyecare Guidelines or making any management decisions based upon them, all users should read the ‘supporting information’ page which gives more detail around the content of the Guidelines and useful website links [link to Supporting Information page].

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Users should note that that the Eyecare Guidelines guidance is not mandatory. The guidelines will not be suitable for every situation and they are not intended to be a substitute for specialist expertise and clinical judgement. Users assume all responsibility for using/interpreting the information within the Eyecare Guidelines section of the website. Users should also note that the Eyecare Guidelines should not be adhered to in isolation and should be considered in conjunction with other national and locally available guidance/pathways. 

Updating the Eyecare Guidelines requires a continuous process; the date of the last review for each guideline will be clearly noted on each guideline. Users must consider these dates before using the guidance.

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