Clinical Management Guidelines

The CMGs offer information on the diagnosis and management of a range of conditions that present with varying frequency in primary and first contact care.

Clinical Management Guidelines

The CMGs offer information on the diagnosis and management of a range of conditions that present with varying frequency in primary and first contact care.

Abnormalities of the Pupil

Contents

Aetiology

Although pupil anomalies are commonly benign, they may be the first or only manifestation of a serious or even life-threatening disorder.

Physiological (‘simple’) anisocoria

Tonic (Adie’s) pupil

Argyll Robertson pupil

Predisposing factors

Argyll Robertson pupil

Symptoms of pupil abnormalities

Generally asymptomatic, although pupil abnormalities may be associated with pain, photophobia or visual disturbance

Ipsilateral orbital, face, or neck pain has been reported in up to 58% of cases of Horner’s syndrome associated with internal carotid artery dissection

Signs of pupil abnormalities

Physiological (‘simple’) anisocoria

Tonic (Adie’s) pupil

Argyll Robertson pupil

ConditionPupillary signsAssociated
features
Physiological
anisocoria		Unequal pupil sizes ≥0.5mm but similar in light and dark conditionsNone
Tonic pupilAffected pupil larger.
Decreased response to light but normal near response		Rare, but could include varicella-zoster infection, giant cell arteritis and orbital trauma
Horner’s
syndrome		Miosis of affected pupilMild ptosis and anhydrosis on affected side.
Heterochromia if congenital
Argyll-Robertson pupilBilateral miosis.
Minimal or no reaction to light but normal near response		Neurosyphilis (rare manifestation)

Differential diagnosis

Mechanical causes such as posterior synechiae, iris sphincter tears, or surgical injury

Management by optometrist

Practitioners should work within their scope of practice and where necessary seek further advice or refer the patient elsewhere

Non pharmacological

For physiological anisocoria, old photographs can be diagnostically helpful
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Take thorough history including use of new medications that could affect the pupil, associated visual and/or neurological symptoms, previous or current malignancies and recent head or neck trauma. Initial slit lamp assessment to exclude mechanical causes such as posterior synechiae or iris sphincter tears
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Examination should include extraocular motility and whether or not ptosis is present
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Pharmacological

Pharmacological testing is of limited value due to poor availability of the reagents and high false positive and false negative rates.
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Management category

A1: emergency (same day) referral without intervention if Horner’s syndrome is associated with neck pain. This should be considered a neurological emergency as it could indicate a carotid artery dissection

B2: alleviation/palliation; normally no referral

B1: Refer to ophthalmologist or neurologist.

Possible management in secondary care or local primary/community pathways where available

Additional guidance may be available

Often requires investigation and management by multi-disciplinary team

Evidence base

*GRADE: Grading of Recommendations Assessment, Development and Evaluation (see www.gradeworkinggroup.org)

Sources of evidence

Gross JR, McClelland CM, Lee MS. An approach to anisocoria. Curr Opin Ophthalmol. 2016;27(6):486-492.

Lam BL, Thompson HS, Corbett JJ. The prevalence of simple anisocoria. Am J Ophthalmol. 1987;104(1):69-73.

Moeller JJ, Maxner CE. The dilated pupil: an update. Curr Neurol Neurosci Rep. 2007;7(5):417-22.

Wilhelm H. Disorders of the pupil. Handb Clin Neurol. 2011;102:427-66.

Xu SY, Song MM, Li L, Li CX. Adie's Pupil: A Diagnostic Challenge for the Physician. Med Sci Monit. 2022;28:e934657.

Summary

What are Abnormalities of the Pupil?

The pupil (the circular black area in the middle of the coloured part of the eye) is usually the same size as the pupil on the other side, and the two pupils usually react together (for example to light). The pupils have muscles to constrict them (make them smaller) and muscles to dilate them (make them larger) and these are controlled by a network of nerves from the brain which works automatically. We all know that bright light makes the pupils smaller and dim light makes them larger. This makes a 20-times difference to the amount of light entering the eye. The pupils also constrict when we look at near objects (for example when we read), which makes focusing easier.

Normally this system works well, without our being aware of it, but there are many ways in which control can be lost. In a fifth of people, the pupils are usually slightly different in size (‘physiological anisocoria’). This is not a problem.

In 1 in 500 people, the nerves that control pupil constriction in one eye do not work properly (Tonic or Adie’s pupil). Usually a cause cannot be found, but rarely this can affect people following an infection or surgery to the eye socket.

In another condition, there is a small pupil on one side, a drooping of the upper lid, and no sweating on the same side of the face. This is known as Horner’s syndrome. It can occur in babies who are injured during birth, and in people with disease of the blood vessels, cancer or following some types of operation.

In Argyll Robertson pupil, both pupils are small and there is no reaction to light, but constriction for looking at near objects still happens. This condition is usually seen at a late stage of the sexually-transmitted infection syphilis and shows that the disease has affected the nervous system.

How is Abnormalities of the Pupil managed?

The optometrist who finds one of these conditions will either take no action, having explained the findings to the patient, or refer the patient to the ophthalmologist or neurologist if tests are needed.

Last updated

Abnormalities of the pupil
Version 2
Date of search 24.08.22
Date of revision 05.09.22
Date of publication 19.12.22
Date for review 23.08.24

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