Argyll Robertson Pupils

Argyll Robertson pupils are a classic neurological finding characterized by small, irregular pupils that fail to constrict to light but constrict normally when focusing on near objects. This pattern, called "light-near dissociation," is historically associated with neurosyphilis but can occur with other conditions affecting the brainstem.

Understanding Argyll Robertson Pupils

The pupil normally constricts to both light and near focus (accommodation). These reflexes use similar pathways but are not identical. In Argyll Robertson pupils, the pathway for the light reflex is damaged while the near reflex pathway remains intact. The result is pupils that respond to looking at something close but not to a bright light.

Characteristics

Classic Features

• Small pupils (miosis)
• Irregular pupil shape
• Bilateral (both eyes affected)
• Poor or absent light response
• Preserved near response
• Poor dilation in dark

The Mnemonic

"Prostitutes accommodate but don't react"—a historical reference to syphilis (the classic cause) noting that pupils accommodate (constrict to near) but don't react (to light).

Symptoms

Visual Symptoms

• Often none—many patients don't notice
• Possible photophobia in bright light
• Difficulty seeing in dim light (pupils don't dilate well)

Associated Symptoms (Depend on Cause)

With neurosyphilis:

• May have other neurological symptoms
• Cognitive changes
• Balance problems
• Lightning pains

Causes

Classic Cause

Neurosyphilis (tertiary syphilis)

• Now rare due to antibiotic treatment
• Still occurs in untreated cases
• Other syphilis manifestations may be present

Other Causes

• Diabetes mellitus (diabetic pupil)
• Lyme disease (neuroborreliosis)
• Herpes zoster
• Encephalitis
• Multiple sclerosis (rarely)
• Midbrain lesions

Diagnosis

Clinical Examination

• Observe pupil size and shape
• Test light response (should be absent/minimal)
• Test near response (should be preserved)
• Slit lamp examination for pupil details

Testing for Syphilis

• RPR/VDRL (screening tests)
• Treponemal tests (FTA-ABS, TP-PA)
• Lumbar puncture if neurosyphilis suspected (CSF VDRL)

Other Testing

• Blood glucose (diabetes)
• Lyme serology
• MRI brain if structural cause suspected

Treatment

Treat Underlying Cause

For neurosyphilis:

• IV penicillin
• Treatment may stabilize but not reverse pupil findings

For other causes:

• Treat underlying condition
• Diabetes management
• Appropriate antibiotics for infections

Symptomatic Treatment

• Dark glasses if photophobia
• Generally no specific treatment for the pupils

Prognosis

Variable

• Pupil findings often permanent even with treatment
• Importance lies in identifying and treating underlying cause
• Neurosyphilis can progress if untreated

Historical Context

Argyll Robertson pupils were first described in 1869 and became an important diagnostic sign for syphilis before serological testing was available. With modern antibiotic treatment, classic Argyll Robertson pupils have become rare, but the finding remains clinically relevant.

Frequently Asked Questions

Does this mean I have syphilis?

Not necessarily. While Argyll Robertson pupils are classically associated with syphilis, other conditions can cause similar findings. Your doctor will test for syphilis and other potential causes.

Will treatment fix my pupils?

Usually not. Even with treatment of the underlying cause, the pupil abnormalities often persist. However, treatment prevents progression of the underlying disease.

Is this dangerous?

The pupil findings themselves are not dangerous. However, they may indicate an underlying condition (like syphilis or diabetes) that needs treatment.

References